diff --git a/.php_cs.dist b/.php_cs.dist
index 41666f1..9879a52 100644
--- a/.php_cs.dist
+++ b/.php_cs.dist
@@ -21,6 +21,7 @@ $config = PhpCsFixer\Config::create()
         'no_null_property_initialization' => true,
         'no_short_echo_tag' => true,
         'no_superfluous_elseif' => true,
+        'no_superfluous_phpdoc_tags' => false,
         'no_unneeded_control_parentheses' => ['statements' => ['break', 'clone', 'continue', 'echo_print', 'switch_case', 'yield']],
         'no_unneeded_curly_braces' => true,
         'no_unneeded_final_method' => true,
diff --git a/.travis.yml b/.travis.yml
index 6df82ba..ac931ed 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,4 @@
-dist: trusty
+dist: bionic
 sudo: false
 
 language: php
@@ -13,6 +13,9 @@ matrix:
       env: WITH_PHPUNIT=true
     - php: 7.3
       env: WITH_PHPUNIT=true
+    - php: 7.4
+      env: WITH_PHPUNIT=true
+
 
 cache:
   directories:
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 4cbf577..8fa35c5 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -6,7 +6,7 @@ All contributions are welcome to this project.
 
 Before a contribution can be merged into this project, please fill out the Contributor License Agreement (CLA) located at:
 
-http://opensource.box.com/cla
+https://opensource.box.com/cla
 
 To learn more about CLAs and why they are important to open source projects, please see the [Wikipedia entry](http://en.wikipedia.org/wiki/Contributor_License_Agreement).
 
diff --git a/README.md b/README.md
index 3fbb10b..517f5a4 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # Spout
 
 [![Latest Stable Version](https://poser.pugx.org/box/spout/v/stable)](https://packagist.org/packages/box/spout)
-[![Project Status](http://opensource.box.com/badges/active.svg)](http://opensource.box.com/badges)
+[![Project Status](https://opensource.box.com/badges/active.svg)](https://opensource.box.com/badges)
 [![Build Status](https://travis-ci.org/box/spout.svg?branch=master)](https://travis-ci.org/box/spout)
 [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/box/spout/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/box/spout/?branch=master)
 [![Code Coverage](https://scrutinizer-ci.com/g/box/spout/badges/coverage.png?b=master)](https://scrutinizer-ci.com/g/box/spout/?branch=master)
@@ -15,7 +15,7 @@ Join the community and come discuss about Spout: [![Gitter](https://badges.gitte
 
 ## Documentation
 
-Full documentation can be found at [http://opensource.box.com/spout/](http://opensource.box.com/spout/).
+Full documentation can be found at [https://opensource.box.com/spout/](https://opensource.box.com/spout/).
 
 
 ## Requirements
diff --git a/docs/_config.yml b/docs/_config.yml
index 8244aa4..2d87dab 100755
--- a/docs/_config.yml
+++ b/docs/_config.yml
@@ -10,7 +10,7 @@ title: Spout
 email: oss@box.com
 description: "An open source PHP library to read and write spreadsheet files (XLSX, ODS and CSV), in a fast and scalable way."
 baseurl: "" # the subpath of your site, e.g. /blog
-url: "http://opensource.box.com" # the base hostname & protocol for your site
+url: "https://opensource.box.com" # the base hostname & protocol for your site
 
 # Build settings
 markdown: kramdown
diff --git a/docs/_config_local.yml b/docs/_config_local.yml
new file mode 100644
index 0000000..3602cad
--- /dev/null
+++ b/docs/_config_local.yml
@@ -0,0 +1,7 @@
+# Github Metadata plugin
+repository: box/spout
+plugins:
+  - "jekyll-github-metadata"
+
+github:
+  url: http://localhost:8080
diff --git a/docs/_includes/footer.html b/docs/_includes/footer.html
index b296089..a4c79dd 100755
--- a/docs/_includes/footer.html
+++ b/docs/_includes/footer.html
@@ -11,7 +11,7 @@
 
       <div class="footer-col footer-col-2">
         <ul class="social-media-list">
-          <li><a href="https://github.com/box/spout/issues"><span class="icon icon--github">{% include icon-github.svg %}</span><span class="username">GitHub Issues</span></a></li>
+          <li><a href="{{ site.github.issues_url }}"><span class="icon icon--github">{% include icon-github.svg %}</span><span class="username">GitHub Issues</span></a></li>
         </ul>
       </div>
 
diff --git a/docs/_includes/head.html b/docs/_includes/head.html
index 81da47d..469730e 100755
--- a/docs/_includes/head.html
+++ b/docs/_includes/head.html
@@ -6,12 +6,12 @@
   <title>{% if page.title %}{{ page.title | escape }}{% else %}{{ site.title | escape }}{% endif %}</title>
   <meta name="description" content="{% if page.excerpt %}{{ page.excerpt | strip_html | strip_newlines | truncate: 160 }}{% else %}{{ site.description }}{% endif %}">
 
-  <link rel="stylesheet" href="{{ "/css/main.css" | prepend: site.github.url }}">
+  <link rel="stylesheet" href="{{ "/css/main.css" | prepend: site_url }}">
   {% if site.algolia.enabled %}
   <link rel="stylesheet" href="//cdn.jsdelivr.net/docsearch.js/1/docsearch.min.css" />
   {% endif %}
 
   {% if jekyll.environment == 'production' %}
-  {% include analytics.html %}
+    {% include analytics.html %}
   {% endif %}
 </head>
diff --git a/docs/_includes/header.html b/docs/_includes/header.html
index 7b945f2..5943bc7 100755
--- a/docs/_includes/header.html
+++ b/docs/_includes/header.html
@@ -1,7 +1,7 @@
 <header class="site-header">
 
   <div class="wrapper">
-    <a class="site-title" href="{{ site.github.url }}/">{{ site.title }}</a>
+    <a class="site-title" href="{{ site_url }}/">{{ site.title }}</a>
 
     <nav class="site-nav">
       <a href="#" class="menu-icon">
@@ -12,11 +12,11 @@
         </svg>
       </a>
       <div class="trigger">
-        <a class="page-link" href="{{ site.github.url }}/getting-started/">Getting Started</a>
-        <a class="page-link" href="{{ site.github.url }}/docs/">Documentation</a>
-        <a class="page-link" href="{{ site.github.url }}/guides/">Guides</a>
-        <a class="page-link" href="{{ site.github.url }}/faq/">FAQ</a>
-        <a class="page-link" href="https://github.com/box/spout">
+        <a class="page-link" href="{{ site_url }}/getting-started/">Getting Started</a>
+        <a class="page-link" href="{{ site_url }}/docs/">Documentation</a>
+        <a class="page-link" href="{{ site_url }}/guides/">Guides</a>
+        <a class="page-link" href="{{ site_url }}/faq/">FAQ</a>
+        <a class="page-link" href="{{ site.github.repository_url }}">
             <span class="icon icon--github">{% include icon-github.svg %}</span>
             <span class="username">GitHub</span>
         </a>
diff --git a/docs/_includes/section-fast-and-scalable.html b/docs/_includes/section-fast-and-scalable.html
index 87fafe1..732d341 100644
--- a/docs/_includes/section-fast-and-scalable.html
+++ b/docs/_includes/section-fast-and-scalable.html
@@ -8,4 +8,4 @@
     Writing an ODS file with millions of rows? {{ site.spout_html }} can do it in no time!
 {% endcapture %}
 
-{% include section.html %}
+{% include section.html site_url = include.site_url %}
diff --git a/docs/_includes/section-supported-spreadsheet-types.html b/docs/_includes/section-supported-spreadsheet-types.html
index 2fefcea..7b7cee0 100644
--- a/docs/_includes/section-supported-spreadsheet-types.html
+++ b/docs/_includes/section-supported-spreadsheet-types.html
@@ -11,4 +11,4 @@
     Switching from one type to another is ridiculously easy!
 {% endcapture %}
 
-{% include section.html %}
+{% include section.html site_url=include.site_url %}
diff --git a/docs/_includes/section-why-use-spout.html b/docs/_includes/section-why-use-spout.html
index 65e45e3..d9a1776 100644
--- a/docs/_includes/section-why-use-spout.html
+++ b/docs/_includes/section-why-use-spout.html
@@ -13,8 +13,9 @@
         <li class="feature-check">{{ site.spout_html }}'s API is {{emS}}developer-friendly{{emE}}.</li>
     </ul><br>
     <div class="btn-wrapper">
-        <a href="{{ site.github.url }}/getting-started/" class="page-link"><button class="btn">Get started</button></a>
+        <a href="{{ include.site_url }}/getting-started/" class="page-link"><button class="btn">Get started</button></a>
     </div>
+
 {% endcapture %}
 
-{% include section.html %}
+{% include section.html site_url=include.site_url %}
diff --git a/docs/_includes/section.html b/docs/_includes/section.html
index 3528de6..53d9b05 100755
--- a/docs/_includes/section.html
+++ b/docs/_includes/section.html
@@ -1,4 +1,3 @@
-
 <div class="section {{ sectionClass }} vertical-align-middle">
   <div class="wrapper">
     <div class="description mbl">
@@ -9,7 +8,7 @@
       {% assign sectionIconsAsArray = sectionIcons | split:'~~' %}
       <div class="icons">
       {% for icon in sectionIconsAsArray %}
-        <img src="{{ site.github.url }}/images/{{ icon }}"/>
+        <img src="{{ include.site_url }}/images/{{ icon }}"/>
       {% endfor %}
       </div>
     {% endif %}
diff --git a/docs/_includes/set-global-site-url.html b/docs/_includes/set-global-site-url.html
new file mode 100644
index 0000000..6c59431
--- /dev/null
+++ b/docs/_includes/set-global-site-url.html
@@ -0,0 +1,12 @@
+{% comment %}
+This is a hack to force using HTTPS...
+The URL of the docs should be changed in the repo settings instead
+{% endcomment %}
+{% assign protocol_scheme = page.url | absolute_url | truncate: 5, "" %}
+{%- capture site_url -%}
+  {%- if protocol_scheme == "https" -%}
+    {{ site.github.url | replace: "http://", "https://" }}
+  {%- else -%}
+    {{ site.github.url }}
+  {%- endif -%}
+{%- endcapture -%}
diff --git a/docs/_layouts/default.html b/docs/_layouts/default.html
index 3ed14b2..b95aab0 100755
--- a/docs/_layouts/default.html
+++ b/docs/_layouts/default.html
@@ -1,6 +1,8 @@
 <!DOCTYPE html>
 <html>
 
+  {% include set-global-site-url.html %}
+
   {% include head.html %}
 
   <body>
@@ -13,14 +15,6 @@
 
     {{ content }}
 
-<!--
-    <div class="page-content">
-      <div class="wrapper">
-
-      </div>
-    </div>
--->
-
     {% include footer.html %}
     {% include algolia.html %}
 
diff --git a/docs/_layouts/page.html b/docs/_layouts/page.html
index d8028d5..3f4c0e6 100755
--- a/docs/_layouts/page.html
+++ b/docs/_layouts/page.html
@@ -1,6 +1,7 @@
 ---
 layout: default
 ---
+
 <article class="post">
   <div class="wrapper">
   <header class="post-header">
diff --git a/docs/_layouts/post.html b/docs/_layouts/post.html
deleted file mode 100755
index 3a0fb52..0000000
--- a/docs/_layouts/post.html
+++ /dev/null
@@ -1,15 +0,0 @@
----
-layout: default
----
-<article class="post" itemscope itemtype="http://schema.org/BlogPosting">
-
-  <header class="post-header">
-    <h1 class="post-title" itemprop="name headline">{{ page.title }}</h1>
-    <p class="post-meta"><time datetime="{{ page.date | date_to_xmlschema }}" itemprop="datePublished">{{ page.date | date: "%b %-d, %Y" }}</time>{% if page.author %} • <span itemprop="author" itemscope itemtype="http://schema.org/Person"><span itemprop="name">{{ page.author }}</span></span>{% endif %}</p>
-  </header>
-
-  <div class="post-content" itemprop="articleBody">
-    {{ content }}
-  </div>
-
-</article>
diff --git a/docs/_pages/documentation.md b/docs/_pages/documentation.md
index 553cf67..d63ca03 100755
--- a/docs/_pages/documentation.md
+++ b/docs/_pages/documentation.md
@@ -116,16 +116,17 @@ $reader->setShouldPreserveEmptyRows(true);
 
 For fonts and alignments, {{ site.spout_html }} does not support all the possible formatting options yet. But you can find the most important ones:
 
-| Category  | Property      | API
-|:----------|:--------------|:--------------------------------------
-| Font      | Bold          | `StyleBuilder::setFontBold()`
-|           | Italic        | `StyleBuilder::setFontItalic()`
-|           | Underline     | `StyleBuilder::setFontUnderline()`
-|           | Strikethrough | `StyleBuilder::setFontStrikethrough()`
-|           | Font name     | `StyleBuilder::setFontName('Arial')`
-|           | Font size     | `StyleBuilder::setFontSize(14)`
-|           | Font color    | `StyleBuilder::setFontColor(Color::BLUE)`<br>`StyleBuilder::setFontColor(Color::rgb(0, 128, 255))`
-| Alignment | Wrap text     | `StyleBuilder::setShouldWrapText(true|false)`
+| Category  | Property       | API
+|:----------|:---------------|:--------------------------------------
+| Font      | Bold           | `StyleBuilder::setFontBold()`
+|           | Italic         | `StyleBuilder::setFontItalic()`
+|           | Underline      | `StyleBuilder::setFontUnderline()`
+|           | Strikethrough  | `StyleBuilder::setFontStrikethrough()`
+|           | Font name      | `StyleBuilder::setFontName('Arial')`
+|           | Font size      | `StyleBuilder::setFontSize(14)`
+|           | Font color     | `StyleBuilder::setFontColor(Color::BLUE)`<br>`StyleBuilder::setFontColor(Color::rgb(0, 128, 255))`
+| Alignment | Cell alignment | `StyleBuilder::setCellAlignment(CellAlignment::CENTER)`
+|           | Wrap text      | `StyleBuilder::setShouldWrapText(true)`
 
 
 ### Styling rows
@@ -135,6 +136,7 @@ It is possible to apply some formatting options to a row. In this case, all cell
 ```php
 use Box\Spout\Writer\Common\Creator\WriterEntityFactory;
 use Box\Spout\Writer\Common\Creator\Style\StyleBuilder;
+use Box\Spout\Common\Entity\Style\CellAlignment;
 use Box\Spout\Common\Entity\Style\Color;
 
 $writer = WriterEntityFactory::createXLSXWriter();
@@ -146,6 +148,7 @@ $style = (new StyleBuilder())
            ->setFontSize(15)
            ->setFontColor(Color::BLUE)
            ->setShouldWrapText()
+           ->setCellAlignment(CellAlignment::RIGHT)
            ->setBackgroundColor(Color::YELLOW)
            ->build();
 
diff --git a/docs/_pages/getting-started.md b/docs/_pages/getting-started.md
index 39a29f7..0004d4d 100755
--- a/docs/_pages/getting-started.md
+++ b/docs/_pages/getting-started.md
@@ -4,6 +4,8 @@ title: Getting Started
 permalink: /getting-started/
 ---
 
+{% include set-global-site-url.html %}
+
 This guide will help you install {{ site.spout_html }} and teach you how to use it.
 
 ## Requirements
@@ -134,4 +136,4 @@ For XLSX and ODS files, the number of rows per sheet is limited to *1,048,576*.
 
 ## Advanced usage
 
-You can do a lot more with {{ site.spout_html }}! Check out the [full documentation]({{ site.github.url }}/docs/) to learn about all the features.
+You can do a lot more with {{ site.spout_html }}! Check out the [full documentation]({{ site_url }}/docs/) to learn about all the features.
diff --git a/docs/_pages/guides.md b/docs/_pages/guides.md
index 5746c8c..37cf124 100644
--- a/docs/_pages/guides.md
+++ b/docs/_pages/guides.md
@@ -4,15 +4,17 @@ title: Guides
 permalink: /guides/
 ---
 
+{% include set-global-site-url.html %}
+
 These guides focus on common and more advanced usages of {{ site.spout_html }}.<br>
-If you are just starting with {{ site.spout_html }}, check out the [Getting Started page]({{ site.github.url }}/getting-started/) and the [Documentation]({{ site.github.url }}/docs/) first.
+If you are just starting with {{ site.spout_html }}, check out the [Getting Started page]({{ site_url }}/getting-started/) and the [Documentation]({{ site_url }}/docs/) first.
 
 {% assign pages=site.pages | sort: 'path' %}
 <ul>
 {% for page in pages %}
   {% if page.title and page.category contains 'guide' %}
   <li>
-    <a class="page-link" href="{{ page.url | prepend: site.github.url }}">{{ page.title }}</a>
+    <a class="page-link" href="{{ page.url | prepend: site_url }}">{{ page.title }}</a>
   </li>
   {% endif %}
 {% endfor %}
diff --git a/docs/_pages/index.md b/docs/_pages/index.md
index a2da586..7949b2b 100644
--- a/docs/_pages/index.md
+++ b/docs/_pages/index.md
@@ -5,6 +5,8 @@ title: Spout - Read and write spreadsheets, quickly and at scale
 permalink: /
 ---
 
-{% include section-supported-spreadsheet-types.html %}
-{% include section-fast-and-scalable.html %}
-{% include section-why-use-spout.html %}
+{% include set-global-site-url.html %}
+
+{% include section-supported-spreadsheet-types.html site_url=site_url %}
+{% include section-fast-and-scalable.html site_url=site_url %}
+{% include section-why-use-spout.html site_url=site_url %}
diff --git a/docs/docker-compose.yml b/docs/docker-compose.yml
index 2cb0093..b7b9a63 100644
--- a/docs/docker-compose.yml
+++ b/docs/docker-compose.yml
@@ -1,7 +1,9 @@
 version: "3"
 services:
   site:
-    command: jekyll serve
+    command: bash -c "
+      gem install 'jekyll-github-metadata'
+      && jekyll serve --config _config.yml,_config_local.yml"
     image: jekyll/jekyll:latest
     volumes:
       - $PWD:/srv/jekyll
@@ -10,4 +12,4 @@ services:
       - 4000:4000
       - 35729:35729
       - 3000:3000
-      - 8080:4000
\ No newline at end of file
+      - 8080:4000
diff --git a/phpunit.xml b/phpunit.xml
index 5c575be..4c56189 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -8,6 +8,10 @@
         defaultTestSuite="unit-tests"
         verbose="false">
 
+    <php>
+        <ini name="error_reporting" value="-1" />
+    </php>
+
     <testsuites>
 
         <testsuite name="unit-tests">
diff --git a/src/Spout/Autoloader/Psr4Autoloader.php b/src/Spout/Autoloader/Psr4Autoloader.php
index 1699293..37b6d4a 100644
--- a/src/Spout/Autoloader/Psr4Autoloader.php
+++ b/src/Spout/Autoloader/Psr4Autoloader.php
@@ -23,7 +23,7 @@ class Psr4Autoloader
      */
     public function register()
     {
-        spl_autoload_register([$this, 'loadClass']);
+        \spl_autoload_register([$this, 'loadClass']);
     }
 
     /**
@@ -40,10 +40,10 @@ class Psr4Autoloader
     public function addNamespace($prefix, $baseDir, $prepend = false)
     {
         // normalize namespace prefix
-        $prefix = trim($prefix, '\\') . '\\';
+        $prefix = \trim($prefix, '\\') . '\\';
 
         // normalize the base directory with a trailing separator
-        $baseDir = rtrim($baseDir, DIRECTORY_SEPARATOR) . '/';
+        $baseDir = \rtrim($baseDir, DIRECTORY_SEPARATOR) . '/';
 
         // initialize the namespace prefix array
         if (isset($this->prefixes[$prefix]) === false) {
@@ -52,9 +52,9 @@ class Psr4Autoloader
 
         // retain the base directory for the namespace prefix
         if ($prepend) {
-            array_unshift($this->prefixes[$prefix], $baseDir);
+            \array_unshift($this->prefixes[$prefix], $baseDir);
         } else {
-            array_push($this->prefixes[$prefix], $baseDir);
+            \array_push($this->prefixes[$prefix], $baseDir);
         }
     }
 
@@ -72,12 +72,12 @@ class Psr4Autoloader
 
         // work backwards through the namespace names of the fully-qualified
         // class name to find a mapped file name
-        while (($pos = strrpos($prefix, '\\')) !== false) {
+        while (($pos = \strrpos($prefix, '\\')) !== false) {
             // retain the trailing namespace separator in the prefix
-            $prefix = substr($class, 0, $pos + 1);
+            $prefix = \substr($class, 0, $pos + 1);
 
             // the rest is the relative class name
-            $relativeClass = substr($class, $pos + 1);
+            $relativeClass = \substr($class, $pos + 1);
 
             // try to load a mapped file for the prefix and relative class
             $mappedFile = $this->loadMappedFile($prefix, $relativeClass);
@@ -87,7 +87,7 @@ class Psr4Autoloader
 
             // remove the trailing namespace separator for the next iteration
             // of strrpos()
-            $prefix = rtrim($prefix, '\\');
+            $prefix = \rtrim($prefix, '\\');
         }
 
         // never found a mapped file
@@ -115,7 +115,7 @@ class Psr4Autoloader
             // replace namespace separators with directory separators
             // in the relative class name, append with .php
             $file = $baseDir
-                  . str_replace('\\', '/', $relativeClass)
+                  . \str_replace('\\', '/', $relativeClass)
                   . '.php';
 
             // if the mapped file exists, require it
@@ -137,7 +137,7 @@ class Psr4Autoloader
      */
     protected function requireFile($file)
     {
-        if (file_exists($file)) {
+        if (\file_exists($file)) {
             require $file;
 
             return true;
diff --git a/src/Spout/Autoloader/autoload.php b/src/Spout/Autoloader/autoload.php
index e08ee34..44468a7 100644
--- a/src/Spout/Autoloader/autoload.php
+++ b/src/Spout/Autoloader/autoload.php
@@ -8,7 +8,7 @@ require_once 'Psr4Autoloader.php';
  * @var string
  * Full path to "src/Spout" which is what we want "Box\Spout" to map to.
  */
-$srcBaseDirectory = dirname(dirname(__FILE__));
+$srcBaseDirectory = \dirname(\dirname(__FILE__));
 
 $loader = new Psr4Autoloader();
 $loader->register();
diff --git a/src/Spout/Common/Entity/Cell.php b/src/Spout/Common/Entity/Cell.php
index bd7a730..c1de389 100644
--- a/src/Spout/Common/Entity/Cell.php
+++ b/src/Spout/Common/Entity/Cell.php
@@ -91,6 +91,14 @@ class Cell
         return !$this->isError() ? $this->value : null;
     }
 
+    /**
+     * @return mixed
+     */
+    public function getValueEvenIfError()
+    {
+        return $this->value;
+    }
+
     /**
      * @param Style|null $style
      */
diff --git a/src/Spout/Common/Entity/Row.php b/src/Spout/Common/Entity/Row.php
index ccb6bf5..0cc49c7 100644
--- a/src/Spout/Common/Entity/Row.php
+++ b/src/Spout/Common/Entity/Row.php
@@ -70,7 +70,7 @@ class Row
      */
     public function getCellAtIndex($cellIndex)
     {
-        return isset($this->cells[$cellIndex]) ? $this->cells[$cellIndex] : null;
+        return $this->cells[$cellIndex] ?? null;
     }
 
     /**
@@ -89,7 +89,13 @@ class Row
      */
     public function getNumCells()
     {
-        return count($this->cells);
+        // When using "setCellAtIndex", it's possible to
+        // have "$this->cells" contain holes.
+        if (empty($this->cells)) {
+            return 0;
+        }
+
+        return \max(\array_keys($this->cells)) + 1;
     }
 
     /**
@@ -116,7 +122,7 @@ class Row
      */
     public function toArray()
     {
-        return array_map(function (Cell $cell) {
+        return \array_map(function (Cell $cell) {
             return $cell->getValue();
         }, $this->cells);
     }
diff --git a/src/Spout/Common/Entity/Style/BorderPart.php b/src/Spout/Common/Entity/Style/BorderPart.php
index 4dcfd82..c087484 100644
--- a/src/Spout/Common/Entity/Style/BorderPart.php
+++ b/src/Spout/Common/Entity/Style/BorderPart.php
@@ -93,7 +93,7 @@ class BorderPart
      */
     public function setName($name)
     {
-        if (!in_array($name, self::$allowedNames)) {
+        if (!\in_array($name, self::$allowedNames)) {
             throw new InvalidNameException($name);
         }
         $this->name = $name;
@@ -114,7 +114,7 @@ class BorderPart
      */
     public function setStyle($style)
     {
-        if (!in_array($style, self::$allowedStyles)) {
+        if (!\in_array($style, self::$allowedStyles)) {
             throw new InvalidStyleException($style);
         }
         $this->style = $style;
@@ -152,7 +152,7 @@ class BorderPart
      */
     public function setWidth($width)
     {
-        if (!in_array($width, self::$allowedWidths)) {
+        if (!\in_array($width, self::$allowedWidths)) {
             throw new InvalidWidthException($width);
         }
         $this->width = $width;
diff --git a/src/Spout/Common/Entity/Style/CellAlignment.php b/src/Spout/Common/Entity/Style/CellAlignment.php
new file mode 100644
index 0000000..60fe833
--- /dev/null
+++ b/src/Spout/Common/Entity/Style/CellAlignment.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Box\Spout\Common\Entity\Style;
+
+/**
+ * Class Alignment
+ * This class provides constants to work with text alignment.
+ */
+abstract class CellAlignment
+{
+    const LEFT = 'left';
+    const RIGHT = 'right';
+    const CENTER = 'center';
+    const JUSTIFY = 'justify';
+
+    private static $VALID_ALIGNMENTS = [
+        self::LEFT => 1,
+        self::RIGHT => 1,
+        self::CENTER => 1,
+        self::JUSTIFY => 1,
+    ];
+
+    /**
+     * @param string $cellAlignment
+     *
+     * @return bool Whether the given cell alignment is valid
+     */
+    public static function isValid($cellAlignment)
+    {
+        return isset(self::$VALID_ALIGNMENTS[$cellAlignment]);
+    }
+}
diff --git a/src/Spout/Common/Entity/Style/Color.php b/src/Spout/Common/Entity/Style/Color.php
index 36b3d26..f2a4731 100644
--- a/src/Spout/Common/Entity/Style/Color.php
+++ b/src/Spout/Common/Entity/Style/Color.php
@@ -8,7 +8,7 @@ use Box\Spout\Common\Exception\InvalidColorException;
  * Class Color
  * This class provides constants and functions to work with colors
  */
-class Color
+abstract class Color
 {
     /** Standard colors - based on Office Online */
     const BLACK = '000000';
@@ -38,7 +38,7 @@ class Color
         self::throwIfInvalidColorComponentValue($green);
         self::throwIfInvalidColorComponentValue($blue);
 
-        return strtoupper(
+        return \strtoupper(
             self::convertColorComponentToHex($red) .
             self::convertColorComponentToHex($green) .
             self::convertColorComponentToHex($blue)
@@ -54,7 +54,7 @@ class Color
      */
     protected static function throwIfInvalidColorComponentValue($colorComponent)
     {
-        if (!is_int($colorComponent) || $colorComponent < 0 || $colorComponent > 255) {
+        if (!\is_int($colorComponent) || $colorComponent < 0 || $colorComponent > 255) {
             throw new InvalidColorException("The RGB components must be between 0 and 255. Received: $colorComponent");
         }
     }
@@ -67,7 +67,7 @@ class Color
      */
     protected static function convertColorComponentToHex($colorComponent)
     {
-        return str_pad(dechex($colorComponent), 2, '0', STR_PAD_LEFT);
+        return \str_pad(\dechex($colorComponent), 2, '0', STR_PAD_LEFT);
     }
 
     /**
diff --git a/src/Spout/Common/Entity/Style/Style.php b/src/Spout/Common/Entity/Style/Style.php
index b34e036..7e989a4 100644
--- a/src/Spout/Common/Entity/Style/Style.php
+++ b/src/Spout/Common/Entity/Style/Style.php
@@ -8,7 +8,7 @@ namespace Box\Spout\Common\Entity\Style;
  */
 class Style
 {
-    /** Default font values */
+    /** Default values */
     const DEFAULT_FONT_SIZE = 11;
     const DEFAULT_FONT_COLOR = Color::BLACK;
     const DEFAULT_FONT_NAME = 'Arial';
@@ -54,6 +54,13 @@ class Style
     /** @var bool Whether specific font properties should be applied */
     private $shouldApplyFont = false;
 
+    /** @var bool Whether specific cell alignment should be applied */
+    private $shouldApplyCellAlignment = false;
+    /** @var string Cell alignment */
+    private $cellAlignment;
+    /** @var bool Whether the cell alignment property was set */
+    private $hasSetCellAlignment = false;
+
     /** @var bool Whether the text should wrap in the cell (useful for long or multi-lines text) */
     private $shouldWrapText = false;
     /** @var bool Whether the wrap text property was set */
@@ -71,6 +78,12 @@ class Style
     /** @var bool */
     private $hasSetBackgroundColor = false;
 
+    /** @var string Format */
+    private $format;
+
+    /** @var bool */
+    private $hasSetFormat = false;
+
     /**
      * @return int|null
      */
@@ -319,6 +332,44 @@ class Style
         return $this->hasSetFontName;
     }
 
+    /**
+     * @return string
+     */
+    public function getCellAlignment()
+    {
+        return $this->cellAlignment;
+    }
+
+    /**
+     * @param string $cellAlignment The cell alignment
+     *
+     * @return Style
+     */
+    public function setCellAlignment($cellAlignment)
+    {
+        $this->cellAlignment = $cellAlignment;
+        $this->hasSetCellAlignment = true;
+        $this->shouldApplyCellAlignment = true;
+
+        return $this;
+    }
+
+    /**
+     * @return bool
+     */
+    public function hasSetCellAlignment()
+    {
+        return $this->hasSetCellAlignment;
+    }
+
+    /**
+     * @return bool Whether specific cell alignment should be applied
+     */
+    public function shouldApplyCellAlignment()
+    {
+        return $this->shouldApplyCellAlignment;
+    }
+
     /**
      * @return bool
      */
@@ -383,4 +434,33 @@ class Style
     {
         return $this->hasSetBackgroundColor;
     }
+
+    /**
+     * Sets format
+     * @param string $format
+     * @return Style
+     */
+    public function setFormat($format)
+    {
+        $this->hasSetFormat = true;
+        $this->format = $format;
+
+        return $this;
+    }
+
+    /**
+     * @return string
+     */
+    public function getFormat()
+    {
+        return $this->format;
+    }
+
+    /**
+     * @return bool Whether format should be applied
+     */
+    public function shouldApplyFormat()
+    {
+        return $this->hasSetFormat;
+    }
 }
diff --git a/src/Spout/Common/Helper/CellTypeHelper.php b/src/Spout/Common/Helper/CellTypeHelper.php
index 03d26a3..97d2e8d 100644
--- a/src/Spout/Common/Helper/CellTypeHelper.php
+++ b/src/Spout/Common/Helper/CellTypeHelper.php
@@ -23,7 +23,7 @@ class CellTypeHelper
      */
     public static function isNonEmptyString($value)
     {
-        return (gettype($value) === 'string' && $value !== '');
+        return (\gettype($value) === 'string' && $value !== '');
     }
 
     /**
@@ -35,7 +35,7 @@ class CellTypeHelper
      */
     public static function isNumeric($value)
     {
-        $valueType = gettype($value);
+        $valueType = \gettype($value);
 
         return ($valueType === 'integer' || $valueType === 'double');
     }
@@ -49,7 +49,7 @@ class CellTypeHelper
      */
     public static function isBoolean($value)
     {
-        return gettype($value) === 'boolean';
+        return \gettype($value) === 'boolean';
     }
 
     /**
diff --git a/src/Spout/Common/Helper/EncodingHelper.php b/src/Spout/Common/Helper/EncodingHelper.php
index 9064274..62ddf60 100644
--- a/src/Spout/Common/Helper/EncodingHelper.php
+++ b/src/Spout/Common/Helper/EncodingHelper.php
@@ -61,7 +61,7 @@ class EncodingHelper
             $bomUsed = $this->supportedEncodingsWithBom[$encoding];
 
             // we skip the N first bytes
-            $byteOffsetToSkipBom = strlen($bomUsed);
+            $byteOffsetToSkipBom = \strlen($bomUsed);
         }
 
         return $byteOffsetToSkipBom;
@@ -80,9 +80,9 @@ class EncodingHelper
 
         $this->globalFunctionsHelper->rewind($filePointer);
 
-        if (array_key_exists($encoding, $this->supportedEncodingsWithBom)) {
+        if (\array_key_exists($encoding, $this->supportedEncodingsWithBom)) {
             $potentialBom = $this->supportedEncodingsWithBom[$encoding];
-            $numBytesInBom = strlen($potentialBom);
+            $numBytesInBom = \strlen($potentialBom);
 
             $hasBOM = ($this->globalFunctionsHelper->fgets($filePointer, $numBytesInBom + 1) === $potentialBom);
         }
diff --git a/src/Spout/Common/Helper/Escaper/ODS.php b/src/Spout/Common/Helper/Escaper/ODS.php
index 5420836..b7e6eb1 100644
--- a/src/Spout/Common/Helper/Escaper/ODS.php
+++ b/src/Spout/Common/Helper/Escaper/ODS.php
@@ -18,14 +18,14 @@ class ODS implements EscaperInterface
     {
         // @NOTE: Using ENT_QUOTES as XML entities ('<', '>', '&') as well as
         //        single/double quotes (for XML attributes) need to be encoded.
-        if (defined('ENT_DISALLOWED')) {
+        if (\defined('ENT_DISALLOWED')) {
             // 'ENT_DISALLOWED' ensures that invalid characters in the given document type are replaced.
             // Otherwise control characters like a vertical tab "\v" will make the XML document unreadable by the XML processor
             // @link https://github.com/box/spout/issues/329
-            $replacedString = htmlspecialchars($string, ENT_QUOTES | ENT_DISALLOWED, 'UTF-8');
+            $replacedString = \htmlspecialchars($string, ENT_QUOTES | ENT_DISALLOWED, 'UTF-8');
         } else {
             // We are on hhvm or any other engine that does not support ENT_DISALLOWED.
-            $escapedString =  htmlspecialchars($string, ENT_QUOTES, 'UTF-8');
+            $escapedString =  \htmlspecialchars($string, ENT_QUOTES, 'UTF-8');
 
             // control characters values are from 0 to 1F (hex values) in the ASCII table
             // some characters should not be escaped though: "\t", "\r" and "\n".
@@ -34,7 +34,7 @@ class ODS implements EscaperInterface
                             '\x0B-\x0C' .
                             // skipping "\r" (0xD)
                             '\x0E-\x1F]';
-            $replacedString = preg_replace("/$regexPattern/", '�', $escapedString);
+            $replacedString = \preg_replace("/$regexPattern/", '�', $escapedString);
         }
 
         return $replacedString;
diff --git a/src/Spout/Common/Helper/Escaper/XLSX.php b/src/Spout/Common/Helper/Escaper/XLSX.php
index d72caa8..daef46e 100644
--- a/src/Spout/Common/Helper/Escaper/XLSX.php
+++ b/src/Spout/Common/Helper/Escaper/XLSX.php
@@ -28,7 +28,7 @@ class XLSX implements EscaperInterface
         if (!$this->isAlreadyInitialized) {
             $this->escapableControlCharactersPattern = $this->getEscapableControlCharactersPattern();
             $this->controlCharactersEscapingMap = $this->getControlCharactersEscapingMap();
-            $this->controlCharactersEscapingReverseMap = array_flip($this->controlCharactersEscapingMap);
+            $this->controlCharactersEscapingReverseMap = \array_flip($this->controlCharactersEscapingMap);
 
             $this->isAlreadyInitialized = true;
         }
@@ -47,7 +47,7 @@ class XLSX implements EscaperInterface
         $escapedString = $this->escapeControlCharacters($string);
         // @NOTE: Using ENT_QUOTES as XML entities ('<', '>', '&') as well as
         //        single/double quotes (for XML attributes) need to be encoded.
-        $escapedString = htmlspecialchars($escapedString, ENT_QUOTES, 'UTF-8');
+        $escapedString = \htmlspecialchars($escapedString, ENT_QUOTES, 'UTF-8');
 
         return $escapedString;
     }
@@ -103,10 +103,10 @@ class XLSX implements EscaperInterface
 
         // control characters values are from 0 to 1F (hex values) in the ASCII table
         for ($charValue = 0x00; $charValue <= 0x1F; $charValue++) {
-            $character = chr($charValue);
-            if (preg_match("/{$this->escapableControlCharactersPattern}/", $character)) {
-                $charHexValue = dechex($charValue);
-                $escapedChar = '_x' . sprintf('%04s', strtoupper($charHexValue)) . '_';
+            $character = \chr($charValue);
+            if (\preg_match("/{$this->escapableControlCharactersPattern}/", $character)) {
+                $charHexValue = \dechex($charValue);
+                $escapedChar = '_x' . \sprintf('%04s', \strtoupper($charHexValue)) . '_';
                 $controlCharactersEscapingMap[$escapedChar] = $character;
             }
         }
@@ -132,11 +132,11 @@ class XLSX implements EscaperInterface
         $escapedString = $this->escapeEscapeCharacter($string);
 
         // if no control characters
-        if (!preg_match("/{$this->escapableControlCharactersPattern}/", $escapedString)) {
+        if (!\preg_match("/{$this->escapableControlCharactersPattern}/", $escapedString)) {
             return $escapedString;
         }
 
-        return preg_replace_callback("/({$this->escapableControlCharactersPattern})/", function ($matches) {
+        return \preg_replace_callback("/({$this->escapableControlCharactersPattern})/", function ($matches) {
             return $this->controlCharactersEscapingReverseMap[$matches[0]];
         }, $escapedString);
     }
@@ -149,7 +149,7 @@ class XLSX implements EscaperInterface
      */
     protected function escapeEscapeCharacter($string)
     {
-        return preg_replace('/_(x[\dA-F]{4})_/', '_x005F_$1_', $string);
+        return \preg_replace('/_(x[\dA-F]{4})_/', '_x005F_$1_', $string);
     }
 
     /**
@@ -171,7 +171,7 @@ class XLSX implements EscaperInterface
 
         foreach ($this->controlCharactersEscapingMap as $escapedCharValue => $charValue) {
             // only unescape characters that don't contain the escaped escape character for now
-            $unescapedString = preg_replace("/(?<!_x005F)($escapedCharValue)/", $charValue, $unescapedString);
+            $unescapedString = \preg_replace("/(?<!_x005F)($escapedCharValue)/", $charValue, $unescapedString);
         }
 
         return $this->unescapeEscapeCharacter($unescapedString);
@@ -185,6 +185,6 @@ class XLSX implements EscaperInterface
      */
     protected function unescapeEscapeCharacter($string)
     {
-        return preg_replace('/_x005F(_x[\dA-F]{4}_)/', '$1', $string);
+        return \preg_replace('/_x005F(_x[\dA-F]{4}_)/', '$1', $string);
     }
 }
diff --git a/src/Spout/Common/Helper/FileSystemHelper.php b/src/Spout/Common/Helper/FileSystemHelper.php
index b1bff8f..4d21fd3 100644
--- a/src/Spout/Common/Helper/FileSystemHelper.php
+++ b/src/Spout/Common/Helper/FileSystemHelper.php
@@ -17,9 +17,9 @@ class FileSystemHelper implements FileSystemHelperInterface
     /**
      * @param string $baseFolderPath The path of the base folder where all the I/O can occur
      */
-    public function __construct($baseFolderPath)
+    public function __construct(string $baseFolderPath)
     {
-        $this->baseFolderRealPath = realpath($baseFolderPath);
+        $this->baseFolderRealPath = \realpath($baseFolderPath);
     }
 
     /**
@@ -36,7 +36,7 @@ class FileSystemHelper implements FileSystemHelperInterface
 
         $folderPath = $parentFolderPath . '/' . $folderName;
 
-        $wasCreationSuccessful = mkdir($folderPath, 0777, true);
+        $wasCreationSuccessful = \mkdir($folderPath, 0777, true);
         if (!$wasCreationSuccessful) {
             throw new IOException("Unable to create folder: $folderPath");
         }
@@ -60,7 +60,7 @@ class FileSystemHelper implements FileSystemHelperInterface
 
         $filePath = $parentFolderPath . '/' . $fileName;
 
-        $wasCreationSuccessful = file_put_contents($filePath, $fileContents);
+        $wasCreationSuccessful = \file_put_contents($filePath, $fileContents);
         if ($wasCreationSuccessful === false) {
             throw new IOException("Unable to create file: $filePath");
         }
@@ -79,8 +79,8 @@ class FileSystemHelper implements FileSystemHelperInterface
     {
         $this->throwIfOperationNotInBaseFolder($filePath);
 
-        if (file_exists($filePath) && is_file($filePath)) {
-            unlink($filePath);
+        if (\file_exists($filePath) && \is_file($filePath)) {
+            \unlink($filePath);
         }
     }
 
@@ -102,13 +102,13 @@ class FileSystemHelper implements FileSystemHelperInterface
 
         foreach ($itemIterator as $item) {
             if ($item->isDir()) {
-                rmdir($item->getPathname());
+                \rmdir($item->getPathname());
             } else {
-                unlink($item->getPathname());
+                \unlink($item->getPathname());
             }
         }
 
-        rmdir($folderPath);
+        \rmdir($folderPath);
     }
 
     /**
@@ -117,13 +117,17 @@ class FileSystemHelper implements FileSystemHelperInterface
      * should occur is not inside the base folder.
      *
      * @param string $operationFolderPath The path of the folder where the I/O operation should occur
-     * @throws \Box\Spout\Common\Exception\IOException If the folder where the I/O operation should occur is not inside the base folder
+     * @throws \Box\Spout\Common\Exception\IOException If the folder where the I/O operation should occur
+     * is not inside the base folder or the base folder does not exist
      * @return void
      */
-    protected function throwIfOperationNotInBaseFolder($operationFolderPath)
+    protected function throwIfOperationNotInBaseFolder(string $operationFolderPath)
     {
-        $operationFolderRealPath = realpath($operationFolderPath);
-        $isInBaseFolder = (strpos($operationFolderRealPath, $this->baseFolderRealPath) === 0);
+        $operationFolderRealPath = \realpath($operationFolderPath);
+        if (!$this->baseFolderRealPath) {
+            throw new IOException("The base folder path is invalid: {$this->baseFolderRealPath}");
+        }
+        $isInBaseFolder = (\strpos($operationFolderRealPath, $this->baseFolderRealPath) === 0);
         if (!$isInBaseFolder) {
             throw new IOException("Cannot perform I/O operation outside of the base folder: {$this->baseFolderRealPath}");
         }
diff --git a/src/Spout/Common/Helper/GlobalFunctionsHelper.php b/src/Spout/Common/Helper/GlobalFunctionsHelper.php
index db33c57..5deb8d9 100644
--- a/src/Spout/Common/Helper/GlobalFunctionsHelper.php
+++ b/src/Spout/Common/Helper/GlobalFunctionsHelper.php
@@ -20,7 +20,7 @@ class GlobalFunctionsHelper
      */
     public function fopen($fileName, $mode)
     {
-        return fopen($fileName, $mode);
+        return \fopen($fileName, $mode);
     }
 
     /**
@@ -33,7 +33,7 @@ class GlobalFunctionsHelper
      */
     public function fgets($handle, $length = null)
     {
-        return fgets($handle, $length);
+        return \fgets($handle, $length);
     }
 
     /**
@@ -46,7 +46,7 @@ class GlobalFunctionsHelper
      */
     public function fputs($handle, $string)
     {
-        return fputs($handle, $string);
+        return \fputs($handle, $string);
     }
 
     /**
@@ -58,7 +58,7 @@ class GlobalFunctionsHelper
      */
     public function fflush($handle)
     {
-        return fflush($handle);
+        return \fflush($handle);
     }
 
     /**
@@ -71,7 +71,7 @@ class GlobalFunctionsHelper
      */
     public function fseek($handle, $offset)
     {
-        return fseek($handle, $offset);
+        return \fseek($handle, $offset);
     }
 
     /**
@@ -92,7 +92,7 @@ class GlobalFunctionsHelper
         // @see http://tools.ietf.org/html/rfc4180
         $escapeCharacter = PHP_VERSION_ID >= 70400 ? '' : "\0";
 
-        return fgetcsv($handle, $length, $delimiter, $enclosure, $escapeCharacter);
+        return \fgetcsv($handle, $length, $delimiter, $enclosure, $escapeCharacter);
     }
 
     /**
@@ -113,7 +113,7 @@ class GlobalFunctionsHelper
         // @see http://tools.ietf.org/html/rfc4180
         $escapeCharacter = PHP_VERSION_ID >= 70400 ? '' : "\0";
 
-        return fputcsv($handle, $fields, $delimiter, $enclosure, $escapeCharacter);
+        return \fputcsv($handle, $fields, $delimiter, $enclosure, $escapeCharacter);
     }
 
     /**
@@ -126,7 +126,7 @@ class GlobalFunctionsHelper
      */
     public function fwrite($handle, $string)
     {
-        return fwrite($handle, $string);
+        return \fwrite($handle, $string);
     }
 
     /**
@@ -138,7 +138,7 @@ class GlobalFunctionsHelper
      */
     public function fclose($handle)
     {
-        return fclose($handle);
+        return \fclose($handle);
     }
 
     /**
@@ -150,7 +150,7 @@ class GlobalFunctionsHelper
      */
     public function rewind($handle)
     {
-        return rewind($handle);
+        return \rewind($handle);
     }
 
     /**
@@ -162,7 +162,7 @@ class GlobalFunctionsHelper
      */
     public function file_exists($fileName)
     {
-        return file_exists($fileName);
+        return \file_exists($fileName);
     }
 
     /**
@@ -176,7 +176,7 @@ class GlobalFunctionsHelper
     {
         $realFilePath = $this->convertToUseRealPath($filePath);
 
-        return file_get_contents($realFilePath);
+        return \file_get_contents($realFilePath);
     }
 
     /**
@@ -191,13 +191,13 @@ class GlobalFunctionsHelper
         $realFilePath = $filePath;
 
         if ($this->isZipStream($filePath)) {
-            if (preg_match('/zip:\/\/(.*)#(.*)/', $filePath, $matches)) {
+            if (\preg_match('/zip:\/\/(.*)#(.*)/', $filePath, $matches)) {
                 $documentPath = $matches[1];
                 $documentInsideZipPath = $matches[2];
-                $realFilePath = 'zip://' . realpath($documentPath) . '#' . $documentInsideZipPath;
+                $realFilePath = 'zip://' . \realpath($documentPath) . '#' . $documentInsideZipPath;
             }
         } else {
-            $realFilePath = realpath($filePath);
+            $realFilePath = \realpath($filePath);
         }
 
         return $realFilePath;
@@ -211,7 +211,7 @@ class GlobalFunctionsHelper
      */
     protected function isZipStream($path)
     {
-        return (strpos($path, 'zip://') === 0);
+        return (\strpos($path, 'zip://') === 0);
     }
 
     /**
@@ -223,7 +223,7 @@ class GlobalFunctionsHelper
      */
     public function feof($handle)
     {
-        return feof($handle);
+        return \feof($handle);
     }
 
     /**
@@ -235,7 +235,7 @@ class GlobalFunctionsHelper
      */
     public function is_readable($fileName)
     {
-        return is_readable($fileName);
+        return \is_readable($fileName);
     }
 
     /**
@@ -248,7 +248,7 @@ class GlobalFunctionsHelper
      */
     public function basename($path, $suffix = null)
     {
-        return basename($path, $suffix);
+        return \basename($path, $suffix);
     }
 
     /**
@@ -260,7 +260,7 @@ class GlobalFunctionsHelper
      */
     public function header($string)
     {
-        header($string);
+        \header($string);
     }
 
     /**
@@ -271,8 +271,8 @@ class GlobalFunctionsHelper
      */
     public function ob_end_clean()
     {
-        if (ob_get_length() > 0) {
-            ob_end_clean();
+        if (\ob_get_length() > 0) {
+            \ob_end_clean();
         }
     }
 
@@ -287,7 +287,7 @@ class GlobalFunctionsHelper
      */
     public function iconv($string, $sourceEncoding, $targetEncoding)
     {
-        return iconv($sourceEncoding, $targetEncoding, $string);
+        return \iconv($sourceEncoding, $targetEncoding, $string);
     }
 
     /**
@@ -301,7 +301,7 @@ class GlobalFunctionsHelper
      */
     public function mb_convert_encoding($string, $sourceEncoding, $targetEncoding)
     {
-        return mb_convert_encoding($string, $targetEncoding, $sourceEncoding);
+        return \mb_convert_encoding($string, $targetEncoding, $sourceEncoding);
     }
 
     /**
@@ -312,7 +312,7 @@ class GlobalFunctionsHelper
      */
     public function stream_get_wrappers()
     {
-        return stream_get_wrappers();
+        return \stream_get_wrappers();
     }
 
     /**
@@ -324,6 +324,6 @@ class GlobalFunctionsHelper
      */
     public function function_exists($functionName)
     {
-        return function_exists($functionName);
+        return \function_exists($functionName);
     }
 }
diff --git a/src/Spout/Common/Helper/StringHelper.php b/src/Spout/Common/Helper/StringHelper.php
index c698815..0906132 100644
--- a/src/Spout/Common/Helper/StringHelper.php
+++ b/src/Spout/Common/Helper/StringHelper.php
@@ -18,7 +18,7 @@ class StringHelper
      */
     public function __construct()
     {
-        $this->hasMbstringSupport = extension_loaded('mbstring');
+        $this->hasMbstringSupport = \extension_loaded('mbstring');
     }
 
     /**
@@ -32,7 +32,7 @@ class StringHelper
      */
     public function getStringLength($string)
     {
-        return $this->hasMbstringSupport ? mb_strlen($string) : strlen($string);
+        return $this->hasMbstringSupport ? \mb_strlen($string) : \strlen($string);
     }
 
     /**
@@ -47,7 +47,7 @@ class StringHelper
      */
     public function getCharFirstOccurrencePosition($char, $string)
     {
-        $position = $this->hasMbstringSupport ? mb_strpos($string, $char) : strpos($string, $char);
+        $position = $this->hasMbstringSupport ? \mb_strpos($string, $char) : \strpos($string, $char);
 
         return ($position !== false) ? $position : -1;
     }
@@ -64,7 +64,7 @@ class StringHelper
      */
     public function getCharLastOccurrencePosition($char, $string)
     {
-        $position = $this->hasMbstringSupport ? mb_strrpos($string, $char) : strrpos($string, $char);
+        $position = $this->hasMbstringSupport ? \mb_strrpos($string, $char) : \strrpos($string, $char);
 
         return ($position !== false) ? $position : -1;
     }
diff --git a/src/Spout/Common/Manager/OptionsManagerAbstract.php b/src/Spout/Common/Manager/OptionsManagerAbstract.php
index 20eb14e..5670b95 100644
--- a/src/Spout/Common/Manager/OptionsManagerAbstract.php
+++ b/src/Spout/Common/Manager/OptionsManagerAbstract.php
@@ -46,7 +46,7 @@ abstract class OptionsManagerAbstract implements OptionsManagerInterface
      */
     public function setOption($optionName, $optionValue)
     {
-        if (in_array($optionName, $this->supportedOptions)) {
+        if (\in_array($optionName, $this->supportedOptions)) {
             $this->options[$optionName] = $optionValue;
         }
     }
diff --git a/src/Spout/Reader/CSV/Creator/InternalEntityFactory.php b/src/Spout/Reader/CSV/Creator/InternalEntityFactory.php
index cdb4197..65cf3eb 100644
--- a/src/Spout/Reader/CSV/Creator/InternalEntityFactory.php
+++ b/src/Spout/Reader/CSV/Creator/InternalEntityFactory.php
@@ -89,7 +89,7 @@ class InternalEntityFactory implements InternalEntityFactoryInterface
      */
     public function createRowFromArray(array $cellValues = [])
     {
-        $cells = array_map(function ($cellValue) {
+        $cells = \array_map(function ($cellValue) {
             return $this->createCell($cellValue);
         }, $cellValues);
 
diff --git a/src/Spout/Reader/CSV/Reader.php b/src/Spout/Reader/CSV/Reader.php
index 77249c1..ca61ef2 100644
--- a/src/Spout/Reader/CSV/Reader.php
+++ b/src/Spout/Reader/CSV/Reader.php
@@ -84,8 +84,8 @@ class Reader extends ReaderAbstract
      */
     protected function openReader($filePath)
     {
-        $this->originalAutoDetectLineEndings = ini_get('auto_detect_line_endings');
-        ini_set('auto_detect_line_endings', '1');
+        $this->originalAutoDetectLineEndings = \ini_get('auto_detect_line_endings');
+        \ini_set('auto_detect_line_endings', '1');
 
         $this->filePointer = $this->globalFunctionsHelper->fopen($filePath, 'r');
         if (!$this->filePointer) {
@@ -123,6 +123,6 @@ class Reader extends ReaderAbstract
             $this->globalFunctionsHelper->fclose($this->filePointer);
         }
 
-        ini_set('auto_detect_line_endings', $this->originalAutoDetectLineEndings);
+        \ini_set('auto_detect_line_endings', $this->originalAutoDetectLineEndings);
     }
 }
diff --git a/src/Spout/Reader/CSV/RowIterator.php b/src/Spout/Reader/CSV/RowIterator.php
index bec3072..78e6650 100644
--- a/src/Spout/Reader/CSV/RowIterator.php
+++ b/src/Spout/Reader/CSV/RowIterator.php
@@ -147,7 +147,7 @@ class RowIterator implements IteratorInterface
 
         if ($rowData !== false) {
             // str_replace will replace NULL values by empty strings
-            $rowDataBufferAsArray = str_replace(null, null, $rowData);
+            $rowDataBufferAsArray = \str_replace(null, null, $rowData);
             $this->rowBuffer = $this->entityFactory->createRowFromArray($rowDataBufferAsArray);
             $this->numReadRows++;
         } else {
@@ -193,13 +193,13 @@ class RowIterator implements IteratorInterface
                 case EncodingHelper::ENCODING_UTF16_LE:
                 case EncodingHelper::ENCODING_UTF32_LE:
                     // remove whitespace from the beginning of a string as fgetcsv() add extra whitespace when it try to explode non UTF-8 data
-                    $cellValue = ltrim($cellValue);
+                    $cellValue = \ltrim($cellValue);
                     break;
 
                 case EncodingHelper::ENCODING_UTF16_BE:
                 case EncodingHelper::ENCODING_UTF32_BE:
                     // remove whitespace from the end of a string as fgetcsv() add extra whitespace when it try to explode non UTF-8 data
-                    $cellValue = rtrim($cellValue);
+                    $cellValue = \rtrim($cellValue);
                     break;
             }
 
@@ -215,7 +215,7 @@ class RowIterator implements IteratorInterface
      */
     protected function isEmptyLine($lineData)
     {
-        return (is_array($lineData) && count($lineData) === 1 && $lineData[0] === null);
+        return (\is_array($lineData) && \count($lineData) === 1 && $lineData[0] === null);
     }
 
     /**
diff --git a/src/Spout/Reader/Common/Creator/ReaderFactory.php b/src/Spout/Reader/Common/Creator/ReaderFactory.php
index 245a42a..6b10175 100644
--- a/src/Spout/Reader/Common/Creator/ReaderFactory.php
+++ b/src/Spout/Reader/Common/Creator/ReaderFactory.php
@@ -37,7 +37,7 @@ class ReaderFactory
      */
     public static function createFromFile(string $path)
     {
-        $extension = strtolower(pathinfo($path, PATHINFO_EXTENSION));
+        $extension = \strtolower(\pathinfo($path, PATHINFO_EXTENSION));
 
         return self::createFromType($extension);
     }
diff --git a/src/Spout/Reader/Common/Manager/RowManager.php b/src/Spout/Reader/Common/Manager/RowManager.php
index ea76255..623c8d8 100644
--- a/src/Spout/Reader/Common/Manager/RowManager.php
+++ b/src/Spout/Reader/Common/Manager/RowManager.php
@@ -47,12 +47,14 @@ class RowManager
      */
     public function fillMissingIndexesWithEmptyCells(Row $row)
     {
-        if ($row->getNumCells() === 0) {
+        $numCells = $row->getNumCells();
+
+        if ($numCells === 0) {
             return $row;
         }
 
         $rowCells = $row->getCells();
-        $maxCellIndex = max(array_keys($rowCells));
+        $maxCellIndex = $numCells;
 
         for ($cellIndex = 0; $cellIndex < $maxCellIndex; $cellIndex++) {
             if (!isset($rowCells[$cellIndex])) {
diff --git a/src/Spout/Reader/Common/XMLProcessor.php b/src/Spout/Reader/Common/XMLProcessor.php
index 3b2d848..05ee970 100644
--- a/src/Spout/Reader/Common/XMLProcessor.php
+++ b/src/Spout/Reader/Common/XMLProcessor.php
@@ -73,7 +73,7 @@ class XMLProcessor
     {
         $callbackObject = $callback[0];
         $callbackMethodName = $callback[1];
-        $reflectionMethod = new \ReflectionMethod(get_class($callbackObject), $callbackMethodName);
+        $reflectionMethod = new \ReflectionMethod(\get_class($callbackObject), $callbackMethodName);
         $reflectionMethod->setAccessible(true);
 
         return [
diff --git a/src/Spout/Reader/ODS/Helper/CellValueFormatter.php b/src/Spout/Reader/ODS/Helper/CellValueFormatter.php
index 50209ec..168770f 100644
--- a/src/Spout/Reader/ODS/Helper/CellValueFormatter.php
+++ b/src/Spout/Reader/ODS/Helper/CellValueFormatter.php
@@ -22,9 +22,11 @@ class CellValueFormatter
 
     /** Definition of XML nodes names used to parse data */
     const XML_NODE_P = 'p';
-    const XML_NODE_S = 'text:s';
-    const XML_NODE_A = 'text:a';
-    const XML_NODE_SPAN = 'text:span';
+    const XML_NODE_TEXT_A = 'text:a';
+    const XML_NODE_TEXT_SPAN = 'text:span';
+    const XML_NODE_TEXT_S = 'text:s';
+    const XML_NODE_TEXT_TAB = 'text:tab';
+    const XML_NODE_TEXT_LINE_BREAK = 'text:line-break';
 
     /** Definition of XML attributes used to parse data */
     const XML_ATTRIBUTE_TYPE = 'office:value-type';
@@ -41,6 +43,13 @@ class CellValueFormatter
     /** @var \Box\Spout\Common\Helper\Escaper\ODS Used to unescape XML data */
     protected $escaper;
 
+    /** @var array List of XML nodes representing whitespaces and their corresponding value */
+    private static $WHITESPACE_XML_NODES = [
+        self::XML_NODE_TEXT_S => ' ',
+        self::XML_NODE_TEXT_TAB => "\t",
+        self::XML_NODE_TEXT_LINE_BREAK => "\n",
+    ];
+
     /**
      * @param bool $shouldFormatDates Whether date/time values should be returned as PHP objects or be formatted as strings
      * @param \Box\Spout\Common\Helper\Escaper\ODS $escaper Used to unescape XML data
@@ -96,29 +105,71 @@ class CellValueFormatter
         $pNodes = $node->getElementsByTagName(self::XML_NODE_P);
 
         foreach ($pNodes as $pNode) {
-            $currentPValue = '';
-
-            foreach ($pNode->childNodes as $childNode) {
-                if ($childNode instanceof \DOMText) {
-                    $currentPValue .= $childNode->nodeValue;
-                } elseif ($childNode->nodeName === self::XML_NODE_S) {
-                    $spaceAttribute = $childNode->getAttribute(self::XML_ATTRIBUTE_C);
-                    $numSpaces = (!empty($spaceAttribute)) ? (int) $spaceAttribute : 1;
-                    $currentPValue .= str_repeat(' ', $numSpaces);
-                } elseif ($childNode->nodeName === self::XML_NODE_A || $childNode->nodeName === self::XML_NODE_SPAN) {
-                    $currentPValue .= $childNode->nodeValue;
-                }
-            }
-
-            $pNodeValues[] = $currentPValue;
+            $pNodeValues[] = $this->extractTextValueFromNode($pNode);
         }
 
-        $escapedCellValue = implode("\n", $pNodeValues);
+        $escapedCellValue = \implode("\n", $pNodeValues);
         $cellValue = $this->escaper->unescape($escapedCellValue);
 
         return $cellValue;
     }
 
+    /**
+     * @param $pNode
+     * @return string
+     */
+    private function extractTextValueFromNode($pNode)
+    {
+        $textValue = '';
+
+        foreach ($pNode->childNodes as $childNode) {
+            if ($childNode instanceof \DOMText) {
+                $textValue .= $childNode->nodeValue;
+            } elseif ($this->isWhitespaceNode($childNode->nodeName)) {
+                $textValue .= $this->transformWhitespaceNode($childNode);
+            } elseif ($childNode->nodeName === self::XML_NODE_TEXT_A || $childNode->nodeName === self::XML_NODE_TEXT_SPAN) {
+                $textValue .= $this->extractTextValueFromNode($childNode);
+            }
+        }
+
+        return $textValue;
+    }
+
+    /**
+     * Returns whether the given node is a whitespace node. It must be one of these:
+     *  - <text:s />
+     *  - <text:tab />
+     *  - <text:line-break />
+     *
+     * @param string $nodeName
+     * @return bool
+     */
+    private function isWhitespaceNode($nodeName)
+    {
+        return isset(self::$WHITESPACE_XML_NODES[$nodeName]);
+    }
+
+    /**
+     * The "<text:p>" node can contain the string value directly
+     * or contain child elements. In this case, whitespaces contain in
+     * the child elements should be replaced by their XML equivalent:
+     *  - space => <text:s />
+     *  - tab => <text:tab />
+     *  - line break => <text:line-break />
+     *
+     * @see https://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part1.html#__RefHeading__1415200_253892949
+     *
+     * @param \DOMNode $node The XML node representing a whitespace
+     * @return string The corresponding whitespace value
+     */
+    private function transformWhitespaceNode($node)
+    {
+        $countAttribute = $node->getAttribute(self::XML_ATTRIBUTE_C); // only defined for "<text:s>"
+        $numWhitespaces = (!empty($countAttribute)) ? (int) $countAttribute : 1;
+
+        return \str_repeat(self::$WHITESPACE_XML_NODES[$node->nodeName], $numWhitespaces);
+    }
+
     /**
      * Returns the cell Numeric value from the given node.
      *
diff --git a/src/Spout/Reader/ReaderAbstract.php b/src/Spout/Reader/ReaderAbstract.php
index dea234e..39b333d 100644
--- a/src/Spout/Reader/ReaderAbstract.php
+++ b/src/Spout/Reader/ReaderAbstract.php
@@ -145,7 +145,7 @@ abstract class ReaderAbstract implements ReaderInterface
         }
 
         // Need to use realpath to fix "Can't open file" on some Windows setup
-        return realpath($filePath);
+        return \realpath($filePath);
     }
 
     /**
@@ -158,7 +158,7 @@ abstract class ReaderAbstract implements ReaderInterface
     protected function getStreamWrapperScheme($filePath)
     {
         $streamScheme = null;
-        if (preg_match('/^(\w+):\/\//', $filePath, $matches)) {
+        if (\preg_match('/^(\w+):\/\//', $filePath, $matches)) {
             $streamScheme = $matches[1];
         }
 
@@ -190,7 +190,7 @@ abstract class ReaderAbstract implements ReaderInterface
         $streamScheme = $this->getStreamWrapperScheme($filePath);
 
         return ($streamScheme !== null) ?
-            in_array($streamScheme, $this->globalFunctionsHelper->stream_get_wrappers()) :
+            \in_array($streamScheme, $this->globalFunctionsHelper->stream_get_wrappers()) :
             true;
     }
 
diff --git a/src/Spout/Reader/Wrapper/XMLInternalErrorsHelper.php b/src/Spout/Reader/Wrapper/XMLInternalErrorsHelper.php
index 7047a94..ecf0dbd 100644
--- a/src/Spout/Reader/Wrapper/XMLInternalErrorsHelper.php
+++ b/src/Spout/Reader/Wrapper/XMLInternalErrorsHelper.php
@@ -20,8 +20,8 @@ trait XMLInternalErrorsHelper
      */
     protected function useXMLInternalErrors()
     {
-        libxml_clear_errors();
-        $this->initialUseInternalErrorsValue = libxml_use_internal_errors(true);
+        \libxml_clear_errors();
+        $this->initialUseInternalErrorsValue = \libxml_use_internal_errors(true);
     }
 
     /**
@@ -48,7 +48,7 @@ trait XMLInternalErrorsHelper
      */
     private function hasXMLErrorOccured()
     {
-        return (libxml_get_last_error() !== false);
+        return (\libxml_get_last_error() !== false);
     }
 
     /**
@@ -60,10 +60,10 @@ trait XMLInternalErrorsHelper
     private function getLastXMLErrorMessage()
     {
         $errorMessage = null;
-        $error = libxml_get_last_error();
+        $error = \libxml_get_last_error();
 
         if ($error !== false) {
-            $errorMessage = trim($error->message);
+            $errorMessage = \trim($error->message);
         }
 
         return $errorMessage;
@@ -74,6 +74,6 @@ trait XMLInternalErrorsHelper
      */
     protected function resetXMLInternalErrorsSetting()
     {
-        libxml_use_internal_errors($this->initialUseInternalErrorsValue);
+        \libxml_use_internal_errors($this->initialUseInternalErrorsValue);
     }
 }
diff --git a/src/Spout/Reader/Wrapper/XMLReader.php b/src/Spout/Reader/Wrapper/XMLReader.php
index bdbaf4d..6f85f32 100644
--- a/src/Spout/Reader/Wrapper/XMLReader.php
+++ b/src/Spout/Reader/Wrapper/XMLReader.php
@@ -46,9 +46,9 @@ class XMLReader extends \XMLReader
     public function getRealPathURIForFileInZip($zipFilePath, $fileInsideZipPath)
     {
         // The file path should not start with a '/', otherwise it won't be found
-        $fileInsideZipPathWithoutLeadingSlash = ltrim($fileInsideZipPath, '/');
+        $fileInsideZipPathWithoutLeadingSlash = \ltrim($fileInsideZipPath, '/');
 
-        return (self::ZIP_WRAPPER . realpath($zipFilePath) . '#' . $fileInsideZipPathWithoutLeadingSlash);
+        return (self::ZIP_WRAPPER . \realpath($zipFilePath) . '#' . $fileInsideZipPathWithoutLeadingSlash);
     }
 
     /**
@@ -62,7 +62,7 @@ class XMLReader extends \XMLReader
         $doesFileExists = false;
 
         $pattern = '/zip:\/\/([^#]+)#(.*)/';
-        if (preg_match($pattern, $zipStreamURI, $matches)) {
+        if (\preg_match($pattern, $zipStreamURI, $matches)) {
             $zipFilePath = $matches[1];
             $innerFilePath = $matches[2];
 
@@ -158,7 +158,7 @@ class XMLReader extends \XMLReader
         // In some cases, the node has a prefix (for instance, "<sheet>" can also be "<x:sheet>").
         // So if the given node name does not have a prefix, we need to look at the unprefixed name ("localName").
         // @see https://github.com/box/spout/issues/233
-        $hasPrefix = (strpos($nodeName, ':') !== false);
+        $hasPrefix = (\strpos($nodeName, ':') !== false);
         $currentNodeName = ($hasPrefix) ? $this->name : $this->localName;
 
         return ($this->nodeType === $nodeType && $currentNodeName === $nodeName);
diff --git a/src/Spout/Reader/XLSX/Helper/CellHelper.php b/src/Spout/Reader/XLSX/Helper/CellHelper.php
index 27b5abf..d970189 100644
--- a/src/Spout/Reader/XLSX/Helper/CellHelper.php
+++ b/src/Spout/Reader/XLSX/Helper/CellHelper.php
@@ -37,7 +37,7 @@ class CellHelper
         $columnIndex = 0;
 
         // Remove row information
-        $columnLetters = preg_replace('/\d/', '', $cellIndex);
+        $columnLetters = \preg_replace('/\d/', '', $cellIndex);
 
         // strlen() is super slow too... Using isset() is way faster and not too unreadable,
         // since we checked before that there are between 1 and 3 letters.
@@ -75,6 +75,6 @@ class CellHelper
      */
     protected static function isValidCellIndex($cellIndex)
     {
-        return (preg_match('/^[A-Z]{1,3}\d+$/', $cellIndex) === 1);
+        return (\preg_match('/^[A-Z]{1,3}\d+$/', $cellIndex) === 1);
     }
 }
diff --git a/src/Spout/Reader/XLSX/Helper/CellValueFormatter.php b/src/Spout/Reader/XLSX/Helper/CellValueFormatter.php
index fba36b1..169c395 100644
--- a/src/Spout/Reader/XLSX/Helper/CellValueFormatter.php
+++ b/src/Spout/Reader/XLSX/Helper/CellValueFormatter.php
@@ -163,7 +163,7 @@ class CellValueFormatter
      */
     protected function formatStrCellValue($nodeValue)
     {
-        $escapedCellValue = trim($nodeValue);
+        $escapedCellValue = \trim($nodeValue);
         $cellValue = $this->escaper->unescape($escapedCellValue);
 
         return $cellValue;
@@ -248,8 +248,8 @@ class CellValueFormatter
         $baseDate = $this->shouldUse1904Dates ? '1904-01-01' : '1899-12-30';
 
         $daysSinceBaseDate = (int) $nodeValue;
-        $timeRemainder = fmod($nodeValue, 1);
-        $secondsRemainder = round($timeRemainder * self::NUM_SECONDS_IN_ONE_DAY, 0);
+        $timeRemainder = \fmod($nodeValue, 1);
+        $secondsRemainder = \round($timeRemainder * self::NUM_SECONDS_IN_ONE_DAY, 0);
 
         $dateObj = \DateTime::createFromFormat('|Y-m-d', $baseDate);
         $dateObj->modify('+' . $daysSinceBaseDate . 'days');
diff --git a/src/Spout/Reader/XLSX/Helper/DateFormatHelper.php b/src/Spout/Reader/XLSX/Helper/DateFormatHelper.php
index 1618af7..4435788 100644
--- a/src/Spout/Reader/XLSX/Helper/DateFormatHelper.php
+++ b/src/Spout/Reader/XLSX/Helper/DateFormatHelper.php
@@ -62,13 +62,13 @@ class DateFormatHelper
         // Remove brackets potentially present at the beginning of the format string
         // and text portion of the format at the end of it (starting with ";")
         // See §18.8.31 of ECMA-376 for more detail.
-        $dateFormat = preg_replace('/^(?:\[\$[^\]]+?\])?([^;]*).*/', '$1', $excelDateFormat);
+        $dateFormat = \preg_replace('/^(?:\[\$[^\]]+?\])?([^;]*).*/', '$1', $excelDateFormat);
 
         // Double quotes are used to escape characters that must not be interpreted.
         // For instance, ["Day " dd] should result in "Day 13" and we should not try to interpret "D", "a", "y"
         // By exploding the format string using double quote as a delimiter, we can get all parts
         // that must be transformed (even indexes) and all parts that must not be (odd indexes).
-        $dateFormatParts = explode('"', $dateFormat);
+        $dateFormatParts = \explode('"', $dateFormat);
 
         foreach ($dateFormatParts as $partIndex => $dateFormatPart) {
             // do not look at odd indexes
@@ -77,19 +77,19 @@ class DateFormatHelper
             }
 
             // Make sure all characters are lowercase, as the mapping table is using lowercase characters
-            $transformedPart = strtolower($dateFormatPart);
+            $transformedPart = \strtolower($dateFormatPart);
 
             // Remove escapes related to non-format characters
-            $transformedPart = str_replace('\\', '', $transformedPart);
+            $transformedPart = \str_replace('\\', '', $transformedPart);
 
             // Apply general transformation first...
-            $transformedPart = strtr($transformedPart, self::$excelDateFormatToPHPDateFormatMapping[self::KEY_GENERAL]);
+            $transformedPart = \strtr($transformedPart, self::$excelDateFormatToPHPDateFormatMapping[self::KEY_GENERAL]);
 
             // ... then apply hour transformation, for 12-hour or 24-hour format
             if (self::has12HourFormatMarker($dateFormatPart)) {
-                $transformedPart = strtr($transformedPart, self::$excelDateFormatToPHPDateFormatMapping[self::KEY_HOUR_12]);
+                $transformedPart = \strtr($transformedPart, self::$excelDateFormatToPHPDateFormatMapping[self::KEY_HOUR_12]);
             } else {
-                $transformedPart = strtr($transformedPart, self::$excelDateFormatToPHPDateFormatMapping[self::KEY_HOUR_24]);
+                $transformedPart = \strtr($transformedPart, self::$excelDateFormatToPHPDateFormatMapping[self::KEY_HOUR_24]);
             }
 
             // overwrite the parts array with the new transformed part
@@ -97,16 +97,16 @@ class DateFormatHelper
         }
 
         // Merge all transformed parts back together
-        $phpDateFormat = implode('"', $dateFormatParts);
+        $phpDateFormat = \implode('"', $dateFormatParts);
 
         // Finally, to have the date format compatible with the DateTime::format() function, we need to escape
         // all characters that are inside double quotes (and double quotes must be removed).
         // For instance, ["Day " dd] should become [\D\a\y\ dd]
-        $phpDateFormat = preg_replace_callback('/"(.+?)"/', function ($matches) {
+        $phpDateFormat = \preg_replace_callback('/"(.+?)"/', function ($matches) {
             $stringToEscape = $matches[1];
-            $letters = preg_split('//u', $stringToEscape, -1, PREG_SPLIT_NO_EMPTY);
+            $letters = \preg_split('//u', $stringToEscape, -1, PREG_SPLIT_NO_EMPTY);
 
-            return '\\' . implode('\\', $letters);
+            return '\\' . \implode('\\', $letters);
         }, $phpDateFormat);
 
         return $phpDateFormat;
@@ -118,6 +118,6 @@ class DateFormatHelper
      */
     private static function has12HourFormatMarker($excelDateFormat)
     {
-        return (stripos($excelDateFormat, 'am/pm') !== false);
+        return (\stripos($excelDateFormat, 'am/pm') !== false);
     }
 }
diff --git a/src/Spout/Reader/XLSX/Manager/OptionsManager.php b/src/Spout/Reader/XLSX/Manager/OptionsManager.php
index 253e009..25fcc5c 100644
--- a/src/Spout/Reader/XLSX/Manager/OptionsManager.php
+++ b/src/Spout/Reader/XLSX/Manager/OptionsManager.php
@@ -29,7 +29,7 @@ class OptionsManager extends OptionsManagerAbstract
      */
     protected function setDefaultOptions()
     {
-        $this->setOption(Options::TEMP_FOLDER, sys_get_temp_dir());
+        $this->setOption(Options::TEMP_FOLDER, \sys_get_temp_dir());
         $this->setOption(Options::SHOULD_FORMAT_DATES, false);
         $this->setOption(Options::SHOULD_PRESERVE_EMPTY_ROWS, false);
         $this->setOption(Options::SHOULD_USE_1904_DATES, false);
diff --git a/src/Spout/Reader/XLSX/Manager/SharedStringsCaching/CachingStrategyFactory.php b/src/Spout/Reader/XLSX/Manager/SharedStringsCaching/CachingStrategyFactory.php
index bc7ee9c..1c00a52 100644
--- a/src/Spout/Reader/XLSX/Manager/SharedStringsCaching/CachingStrategyFactory.php
+++ b/src/Spout/Reader/XLSX/Manager/SharedStringsCaching/CachingStrategyFactory.php
@@ -103,14 +103,14 @@ class CachingStrategyFactory
     protected function getMemoryLimitInKB()
     {
         $memoryLimitFormatted = $this->getMemoryLimitFromIni();
-        $memoryLimitFormatted = strtolower(trim($memoryLimitFormatted));
+        $memoryLimitFormatted = \strtolower(\trim($memoryLimitFormatted));
 
         // No memory limit
         if ($memoryLimitFormatted === '-1') {
             return -1;
         }
 
-        if (preg_match('/(\d+)([bkmgt])b?/', $memoryLimitFormatted, $matches)) {
+        if (\preg_match('/(\d+)([bkmgt])b?/', $memoryLimitFormatted, $matches)) {
             $amount = (int) ($matches[1]);
             $unit = $matches[2];
 
@@ -133,6 +133,6 @@ class CachingStrategyFactory
      */
     protected function getMemoryLimitFromIni()
     {
-        return ini_get('memory_limit');
+        return \ini_get('memory_limit');
     }
 }
diff --git a/src/Spout/Reader/XLSX/Manager/SharedStringsCaching/FileBasedStrategy.php b/src/Spout/Reader/XLSX/Manager/SharedStringsCaching/FileBasedStrategy.php
index c8ded70..0e743b4 100644
--- a/src/Spout/Reader/XLSX/Manager/SharedStringsCaching/FileBasedStrategy.php
+++ b/src/Spout/Reader/XLSX/Manager/SharedStringsCaching/FileBasedStrategy.php
@@ -55,7 +55,7 @@ class FileBasedStrategy implements CachingStrategyInterface
     public function __construct($tempFolder, $maxNumStringsPerTempFile, $helperFactory)
     {
         $this->fileSystemHelper = $helperFactory->createFileSystemHelper($tempFolder);
-        $this->tempFolder = $this->fileSystemHelper->createFolder($tempFolder, uniqid('sharedstrings'));
+        $this->tempFolder = $this->fileSystemHelper->createFolder($tempFolder, \uniqid('sharedstrings'));
 
         $this->maxNumStringsPerTempFile = $maxNumStringsPerTempFile;
 
@@ -135,7 +135,7 @@ class FileBasedStrategy implements CachingStrategyInterface
             // free memory
             unset($this->inMemoryTempFileContents);
 
-            $this->inMemoryTempFileContents = explode(PHP_EOL, $this->globalFunctionsHelper->file_get_contents($tempFilePath));
+            $this->inMemoryTempFileContents = \explode(PHP_EOL, $this->globalFunctionsHelper->file_get_contents($tempFilePath));
             $this->inMemoryTempFilePath = $tempFilePath;
         }
 
@@ -151,7 +151,7 @@ class FileBasedStrategy implements CachingStrategyInterface
             throw new SharedStringNotFoundException("Shared string not found for index: $sharedStringIndex");
         }
 
-        return rtrim($sharedString, PHP_EOL);
+        return \rtrim($sharedString, PHP_EOL);
     }
 
     /**
@@ -162,7 +162,7 @@ class FileBasedStrategy implements CachingStrategyInterface
      */
     private function escapeLineFeed($unescapedString)
     {
-        return str_replace("\n", self::ESCAPED_LINE_FEED_CHARACTER, $unescapedString);
+        return \str_replace("\n", self::ESCAPED_LINE_FEED_CHARACTER, $unescapedString);
     }
 
     /**
@@ -173,7 +173,7 @@ class FileBasedStrategy implements CachingStrategyInterface
      */
     private function unescapeLineFeed($escapedString)
     {
-        return str_replace(self::ESCAPED_LINE_FEED_CHARACTER, "\n", $escapedString);
+        return \str_replace(self::ESCAPED_LINE_FEED_CHARACTER, "\n", $escapedString);
     }
 
     /**
diff --git a/src/Spout/Reader/XLSX/Manager/SharedStringsManager.php b/src/Spout/Reader/XLSX/Manager/SharedStringsManager.php
index 18d4681..caaeed7 100644
--- a/src/Spout/Reader/XLSX/Manager/SharedStringsManager.php
+++ b/src/Spout/Reader/XLSX/Manager/SharedStringsManager.php
@@ -190,7 +190,7 @@ class SharedStringsManager
                 $textNodeValue = $textNode->nodeValue;
                 $shouldPreserveWhitespace = $this->shouldPreserveWhitespace($textNode);
 
-                $sharedStringValue .= ($shouldPreserveWhitespace) ? $textNodeValue : trim($textNodeValue);
+                $sharedStringValue .= ($shouldPreserveWhitespace) ? $textNodeValue : \trim($textNodeValue);
             }
         }
 
diff --git a/src/Spout/Reader/XLSX/Manager/SheetManager.php b/src/Spout/Reader/XLSX/Manager/SheetManager.php
index 42f287d..e7b41e0 100644
--- a/src/Spout/Reader/XLSX/Manager/SheetManager.php
+++ b/src/Spout/Reader/XLSX/Manager/SheetManager.php
@@ -116,7 +116,7 @@ class SheetManager
     {
         // Using "filter_var($x, FILTER_VALIDATE_BOOLEAN)" here because the value of the "date1904" attribute
         // may be the string "false", that is not mapped to the boolean "false" by default...
-        $shouldUse1904Dates = filter_var($xmlReader->getAttribute(self::XML_ATTRIBUTE_DATE_1904), FILTER_VALIDATE_BOOLEAN);
+        $shouldUse1904Dates = \filter_var($xmlReader->getAttribute(self::XML_ATTRIBUTE_DATE_1904), FILTER_VALIDATE_BOOLEAN);
         $this->optionsManager->setOption(Options::SHOULD_USE_1904_DATES, $shouldUse1904Dates);
 
         return XMLProcessor::PROCESSING_CONTINUE;
@@ -211,7 +211,7 @@ class SheetManager
                         $sheetDataXMLFilePath = $xmlReader->getAttribute(self::XML_ATTRIBUTE_TARGET);
 
                         // sometimes, the sheet data file path already contains "/xl/"...
-                        if (strpos($sheetDataXMLFilePath, '/xl/') !== 0) {
+                        if (\strpos($sheetDataXMLFilePath, '/xl/') !== 0) {
                             $sheetDataXMLFilePath = '/xl/' . $sheetDataXMLFilePath;
                             break;
                         }
diff --git a/src/Spout/Reader/XLSX/Manager/StyleManager.php b/src/Spout/Reader/XLSX/Manager/StyleManager.php
index 193324d..d5db0d5 100644
--- a/src/Spout/Reader/XLSX/Manager/StyleManager.php
+++ b/src/Spout/Reader/XLSX/Manager/StyleManager.php
@@ -78,7 +78,7 @@ class StyleManager
     {
         $this->filePath = $filePath;
         $this->entityFactory = $entityFactory;
-        $this->builtinNumFmtIdIndicatingDates = array_keys(self::$builtinNumFmtIdToNumFormatMapping);
+        $this->builtinNumFmtIdIndicatingDates = \array_keys(self::$builtinNumFmtIdToNumFormatMapping);
         $this->hasStylesXMLFile = $workbookRelationshipsManager->hasStylesXMLFile();
         if ($this->hasStylesXMLFile) {
             $this->stylesXMLFilePath = $workbookRelationshipsManager->getStylesXMLFilePath();
@@ -273,7 +273,7 @@ class StyleManager
      */
     protected function isNumFmtIdBuiltInDateFormat($numFmtId)
     {
-        return in_array($numFmtId, $this->builtinNumFmtIdIndicatingDates);
+        return \in_array($numFmtId, $this->builtinNumFmtIdIndicatingDates);
     }
 
     /**
@@ -283,7 +283,7 @@ class StyleManager
     protected function isFormatCodeCustomDateFormat($formatCode)
     {
         // if no associated format code or if using the default "General" format
-        if ($formatCode === null || strcasecmp($formatCode, self::NUMBER_FORMAT_GENERAL) === 0) {
+        if ($formatCode === null || \strcasecmp($formatCode, self::NUMBER_FORMAT_GENERAL) === 0) {
             return false;
         }
 
@@ -298,7 +298,7 @@ class StyleManager
     {
         // Remove extra formatting (what's between [ ], the brackets should not be preceded by a "\")
         $pattern = '((?<!\\\)\[.+?(?<!\\\)\])';
-        $formatCode = preg_replace($pattern, '', $formatCode);
+        $formatCode = \preg_replace($pattern, '', $formatCode);
 
         // custom date formats contain specific characters to represent the date:
         // e - yy - m - d - h - s
@@ -310,7 +310,7 @@ class StyleManager
             // character not preceded by "\" (case insensitive)
             $pattern = '/(?<!\\\)' . $dateFormatCharacter . '/i';
 
-            if (preg_match($pattern, $formatCode)) {
+            if (\preg_match($pattern, $formatCode)) {
                 $hasFoundDateFormatCharacter = true;
                 break;
             }
diff --git a/src/Spout/Reader/XLSX/Manager/WorkbookRelationshipsManager.php b/src/Spout/Reader/XLSX/Manager/WorkbookRelationshipsManager.php
index 68d8709..a153d78 100644
--- a/src/Spout/Reader/XLSX/Manager/WorkbookRelationshipsManager.php
+++ b/src/Spout/Reader/XLSX/Manager/WorkbookRelationshipsManager.php
@@ -55,7 +55,7 @@ class WorkbookRelationshipsManager
         $sharedStringsXMLFilePath = $workbookRelationships[self::RELATIONSHIP_TYPE_SHARED_STRINGS];
 
         // the file path can be relative (e.g. "styles.xml") or absolute (e.g. "/xl/styles.xml")
-        $doesContainBasePath = (strpos($sharedStringsXMLFilePath, self::BASE_PATH) !== false);
+        $doesContainBasePath = (\strpos($sharedStringsXMLFilePath, self::BASE_PATH) !== false);
         if (!$doesContainBasePath) {
             // make sure we return an absolute file path
             $sharedStringsXMLFilePath = self::BASE_PATH . $sharedStringsXMLFilePath;
@@ -93,7 +93,7 @@ class WorkbookRelationshipsManager
         $stylesXMLFilePath = $workbookRelationships[self::RELATIONSHIP_TYPE_STYLES];
 
         // the file path can be relative (e.g. "styles.xml") or absolute (e.g. "/xl/styles.xml")
-        $doesContainBasePath = (strpos($stylesXMLFilePath, self::BASE_PATH) !== false);
+        $doesContainBasePath = (\strpos($stylesXMLFilePath, self::BASE_PATH) !== false);
         if (!$doesContainBasePath) {
             // make sure we return a full path
             $stylesXMLFilePath = self::BASE_PATH . $stylesXMLFilePath;
diff --git a/src/Spout/Reader/XLSX/RowIterator.php b/src/Spout/Reader/XLSX/RowIterator.php
index f161425..4af4530 100644
--- a/src/Spout/Reader/XLSX/RowIterator.php
+++ b/src/Spout/Reader/XLSX/RowIterator.php
@@ -127,7 +127,7 @@ class RowIterator implements IteratorInterface
      */
     protected function normalizeSheetDataXMLFilePath($sheetDataXMLFilePath)
     {
-        return ltrim($sheetDataXMLFilePath, '/');
+        return \ltrim($sheetDataXMLFilePath, '/');
     }
 
     /**
@@ -234,7 +234,7 @@ class RowIterator implements IteratorInterface
     {
         // Read dimensions of the sheet
         $dimensionRef = $xmlReader->getAttribute(self::XML_ATTRIBUTE_REF); // returns 'A1:M13' for instance (or 'A1' for empty sheet)
-        if (preg_match('/[A-Z]+\d+:([A-Z]+\d+)/', $dimensionRef, $matches)) {
+        if (\preg_match('/[A-Z]+\d+:([A-Z]+\d+)/', $dimensionRef, $matches)) {
             $this->numColumns = CellHelper::getColumnIndexFromCellIndex($matches[1]) + 1;
         }
 
@@ -257,11 +257,11 @@ class RowIterator implements IteratorInterface
         $numberOfColumnsForRow = $this->numColumns;
         $spans = $xmlReader->getAttribute(self::XML_ATTRIBUTE_SPANS); // returns '1:5' for instance
         if ($spans) {
-            list(, $numberOfColumnsForRow) = explode(':', $spans);
+            list(, $numberOfColumnsForRow) = \explode(':', $spans);
             $numberOfColumnsForRow = (int) $numberOfColumnsForRow;
         }
 
-        $cells = array_fill(0, $numberOfColumnsForRow, $this->entityFactory->createCell(''));
+        $cells = \array_fill(0, $numberOfColumnsForRow, $this->entityFactory->createCell(''));
         $this->currentlyProcessedRow->setCells($cells);
 
         return XMLProcessor::PROCESSING_CONTINUE;
diff --git a/src/Spout/Reader/XLSX/SheetIterator.php b/src/Spout/Reader/XLSX/SheetIterator.php
index d9ed17c..81f481c 100644
--- a/src/Spout/Reader/XLSX/SheetIterator.php
+++ b/src/Spout/Reader/XLSX/SheetIterator.php
@@ -27,7 +27,7 @@ class SheetIterator implements IteratorInterface
         // Fetch all available sheets
         $this->sheets = $sheetManager->getSheets();
 
-        if (count($this->sheets) === 0) {
+        if (\count($this->sheets) === 0) {
             throw new NoSheetsFoundException('The file must contain at least one sheet.');
         }
     }
@@ -51,7 +51,7 @@ class SheetIterator implements IteratorInterface
      */
     public function valid()
     {
-        return ($this->currentSheetIndex < count($this->sheets));
+        return ($this->currentSheetIndex < \count($this->sheets));
     }
 
     /**
diff --git a/src/Spout/Writer/Common/Creator/Style/StyleBuilder.php b/src/Spout/Writer/Common/Creator/Style/StyleBuilder.php
index a35a280..bc2d406 100644
--- a/src/Spout/Writer/Common/Creator/Style/StyleBuilder.php
+++ b/src/Spout/Writer/Common/Creator/Style/StyleBuilder.php
@@ -3,7 +3,9 @@
 namespace Box\Spout\Writer\Common\Creator\Style;
 
 use Box\Spout\Common\Entity\Style\Border;
+use Box\Spout\Common\Entity\Style\CellAlignment;
 use Box\Spout\Common\Entity\Style\Style;
+use Box\Spout\Common\Exception\InvalidArgumentException;
 
 /**
  * Class StyleBuilder
@@ -122,6 +124,25 @@ class StyleBuilder
         return $this;
     }
 
+    /**
+     * Sets the cell alignment.
+     *
+     * @param string $cellAlignment The cell alignment
+     *
+     * @throws InvalidArgumentException If the given cell alignment is not valid
+     * @return StyleBuilder
+     */
+    public function setCellAlignment($cellAlignment)
+    {
+        if (!CellAlignment::isValid($cellAlignment)) {
+            throw new InvalidArgumentException('Invalid cell alignment value');
+        }
+
+        $this->style->setCellAlignment($cellAlignment);
+
+        return $this;
+    }
+
     /**
      * Set a border
      *
@@ -148,6 +169,20 @@ class StyleBuilder
         return $this;
     }
 
+    /**
+     *  Sets a format
+     *
+     * @param string $format Format
+     * @return StyleBuilder
+     * @api
+     */
+    public function setFormat($format)
+    {
+        $this->style->setFormat($format);
+
+        return $this;
+    }
+
     /**
      * Returns the configured style. The style is cached and can be reused.
      *
diff --git a/src/Spout/Writer/Common/Creator/WriterEntityFactory.php b/src/Spout/Writer/Common/Creator/WriterEntityFactory.php
index 3acbed9..8e43c31 100644
--- a/src/Spout/Writer/Common/Creator/WriterEntityFactory.php
+++ b/src/Spout/Writer/Common/Creator/WriterEntityFactory.php
@@ -98,7 +98,7 @@ class WriterEntityFactory
      */
     public static function createRowFromArray(array $cellValues = [], Style $rowStyle = null)
     {
-        $cells = array_map(function ($cellValue) {
+        $cells = \array_map(function ($cellValue) {
             return new Cell($cellValue);
         }, $cellValues);
 
diff --git a/src/Spout/Writer/Common/Creator/WriterFactory.php b/src/Spout/Writer/Common/Creator/WriterFactory.php
index e504587..96a8eb0 100644
--- a/src/Spout/Writer/Common/Creator/WriterFactory.php
+++ b/src/Spout/Writer/Common/Creator/WriterFactory.php
@@ -35,7 +35,7 @@ class WriterFactory
      */
     public static function createFromFile(string $path)
     {
-        $extension = strtolower(pathinfo($path, PATHINFO_EXTENSION));
+        $extension = \strtolower(\pathinfo($path, PATHINFO_EXTENSION));
 
         return self::createFromType($extension);
     }
diff --git a/src/Spout/Writer/Common/Entity/Workbook.php b/src/Spout/Writer/Common/Entity/Workbook.php
index 782310b..dd18219 100644
--- a/src/Spout/Writer/Common/Entity/Workbook.php
+++ b/src/Spout/Writer/Common/Entity/Workbook.php
@@ -19,7 +19,7 @@ class Workbook
      */
     public function __construct()
     {
-        $this->internalId = uniqid();
+        $this->internalId = \uniqid();
     }
 
     /**
diff --git a/src/Spout/Writer/Common/Helper/CellHelper.php b/src/Spout/Writer/Common/Helper/CellHelper.php
index 472d310..afe3c71 100644
--- a/src/Spout/Writer/Common/Helper/CellHelper.php
+++ b/src/Spout/Writer/Common/Helper/CellHelper.php
@@ -8,38 +8,39 @@ namespace Box\Spout\Writer\Common\Helper;
  */
 class CellHelper
 {
-    /** @var array Cache containing the mapping column index => cell index */
-    private static $columnIndexToCellIndexCache = [];
+    /** @var array Cache containing the mapping column index => column letters */
+    private static $columnIndexToColumnLettersCache = [];
 
     /**
-     * Returns the cell index (base 26) associated to the base 10 column index.
+     * Returns the column letters (base 26) associated to the base 10 column index.
      * Excel uses A to Z letters for column indexing, where A is the 1st column,
      * Z is the 26th and AA is the 27th.
      * The mapping is zero based, so that 0 maps to A, B maps to 1, Z to 25 and AA to 26.
      *
-     * @param int $columnIndex The Excel column index (0, 42, ...)
+     * @param int $columnIndexZeroBased The Excel column index (0, 42, ...)
+     *
      * @return string The associated cell index ('A', 'BC', ...)
      */
-    public static function getCellIndexFromColumnIndex($columnIndex)
+    public static function getColumnLettersFromColumnIndex($columnIndexZeroBased)
     {
-        $originalColumnIndex = $columnIndex;
+        $originalColumnIndex = $columnIndexZeroBased;
 
         // Using isset here because it is way faster than array_key_exists...
-        if (!isset(self::$columnIndexToCellIndexCache[$originalColumnIndex])) {
-            $cellIndex = '';
-            $capitalAAsciiValue = ord('A');
+        if (!isset(self::$columnIndexToColumnLettersCache[$originalColumnIndex])) {
+            $columnLetters = '';
+            $capitalAAsciiValue = \ord('A');
 
             do {
-                $modulus = $columnIndex % 26;
-                $cellIndex = chr($capitalAAsciiValue + $modulus) . $cellIndex;
+                $modulus = $columnIndexZeroBased % 26;
+                $columnLetters = \chr($capitalAAsciiValue + $modulus) . $columnLetters;
 
                 // substracting 1 because it's zero-based
-                $columnIndex = (int) ($columnIndex / 26) - 1;
-            } while ($columnIndex >= 0);
+                $columnIndexZeroBased = (int) ($columnIndexZeroBased / 26) - 1;
+            } while ($columnIndexZeroBased >= 0);
 
-            self::$columnIndexToCellIndexCache[$originalColumnIndex] = $cellIndex;
+            self::$columnIndexToColumnLettersCache[$originalColumnIndex] = $columnLetters;
         }
 
-        return self::$columnIndexToCellIndexCache[$originalColumnIndex];
+        return self::$columnIndexToColumnLettersCache[$originalColumnIndex];
     }
 }
diff --git a/src/Spout/Writer/Common/Helper/ZipHelper.php b/src/Spout/Writer/Common/Helper/ZipHelper.php
index b8fcd6c..7a250c8 100644
--- a/src/Spout/Writer/Common/Helper/ZipHelper.php
+++ b/src/Spout/Writer/Common/Helper/ZipHelper.php
@@ -135,7 +135,7 @@ class ZipHelper
     public static function canChooseCompressionMethod()
     {
         // setCompressionName() is a PHP7+ method...
-        return (method_exists(new \ZipArchive(), 'setCompressionName'));
+        return (\method_exists(new \ZipArchive(), 'setCompressionName'));
     }
 
     /**
@@ -151,7 +151,7 @@ class ZipHelper
 
         foreach ($itemIterator as $itemInfo) {
             $itemRealPath = $this->getNormalizedRealPath($itemInfo->getPathname());
-            $itemLocalPath = str_replace($folderRealPath, '', $itemRealPath);
+            $itemLocalPath = \str_replace($folderRealPath, '', $itemRealPath);
 
             if ($itemInfo->isFile() && !$this->shouldSkipFile($zip, $itemLocalPath, $existingFileMode)) {
                 $zip->addFile($itemRealPath, $itemLocalPath);
@@ -181,9 +181,9 @@ class ZipHelper
      */
     protected function getNormalizedRealPath($path)
     {
-        $realPath = realpath($path);
+        $realPath = \realpath($path);
 
-        return str_replace(DIRECTORY_SEPARATOR, '/', $realPath);
+        return \str_replace(DIRECTORY_SEPARATOR, '/', $realPath);
     }
 
     /**
@@ -210,8 +210,8 @@ class ZipHelper
      */
     protected function copyZipToStream($zipFilePath, $pointer)
     {
-        $zipFilePointer = fopen($zipFilePath, 'r');
-        stream_copy_to_stream($zipFilePointer, $pointer);
-        fclose($zipFilePointer);
+        $zipFilePointer = \fopen($zipFilePath, 'r');
+        \stream_copy_to_stream($zipFilePointer, $pointer);
+        \fclose($zipFilePointer);
     }
 }
diff --git a/src/Spout/Writer/Common/Manager/SheetManager.php b/src/Spout/Writer/Common/Manager/SheetManager.php
index 708137c..d1d4e6a 100644
--- a/src/Spout/Writer/Common/Manager/SheetManager.php
+++ b/src/Spout/Writer/Common/Manager/SheetManager.php
@@ -45,8 +45,8 @@ class SheetManager
      */
     public function throwIfNameIsInvalid($name, Sheet $sheet)
     {
-        if (!is_string($name)) {
-            $actualType = gettype($name);
+        if (!\is_string($name)) {
+            $actualType = \gettype($name);
             $errorMessage = "The sheet's name is invalid. It must be a string ($actualType given).";
             throw new InvalidSheetNameException($errorMessage);
         }
@@ -74,9 +74,9 @@ class SheetManager
             }
         }
 
-        if (count($failedRequirements) !== 0) {
+        if (\count($failedRequirements) !== 0) {
             $errorMessage = "The sheet's name (\"$name\") is invalid. It did not respect these rules:\n - ";
-            $errorMessage .= implode("\n - ", $failedRequirements);
+            $errorMessage .= \implode("\n - ", $failedRequirements);
             throw new InvalidSheetNameException($errorMessage);
         }
     }
@@ -90,7 +90,7 @@ class SheetManager
      */
     private function doesContainInvalidCharacters($name)
     {
-        return (str_replace(self::$INVALID_CHARACTERS_IN_SHEET_NAME, '', $name) !== $name);
+        return (\str_replace(self::$INVALID_CHARACTERS_IN_SHEET_NAME, '', $name) !== $name);
     }
 
     /**
diff --git a/src/Spout/Writer/Common/Manager/Style/StyleManager.php b/src/Spout/Writer/Common/Manager/Style/StyleManager.php
index 36abdc3..77eec73 100644
--- a/src/Spout/Writer/Common/Manager/Style/StyleManager.php
+++ b/src/Spout/Writer/Common/Manager/Style/StyleManager.php
@@ -80,7 +80,7 @@ class StyleManager implements StyleManagerInterface
             return $cellStyle;
         }
 
-        if ($cell->isString() && strpos($cell->getValue(), "\n") !== false) {
+        if ($cell->isString() && \strpos($cell->getValue(), "\n") !== false) {
             $cellStyle->setShouldWrapText();
         }
 
diff --git a/src/Spout/Writer/Common/Manager/Style/StyleMerger.php b/src/Spout/Writer/Common/Manager/Style/StyleMerger.php
index d3446d2..806c8d5 100644
--- a/src/Spout/Writer/Common/Manager/Style/StyleMerger.php
+++ b/src/Spout/Writer/Common/Manager/Style/StyleMerger.php
@@ -85,9 +85,15 @@ class StyleMerger
         if (!$style->hasSetWrapText() && $baseStyle->shouldWrapText()) {
             $styleToUpdate->setShouldWrapText();
         }
+        if (!$style->hasSetCellAlignment() && $baseStyle->shouldApplyCellAlignment()) {
+            $styleToUpdate->setCellAlignment($baseStyle->getCellAlignment());
+        }
         if (!$style->getBorder() && $baseStyle->shouldApplyBorder()) {
             $styleToUpdate->setBorder($baseStyle->getBorder());
         }
+        if (!$style->getFormat() && $baseStyle->shouldApplyFormat()) {
+            $styleToUpdate->setFormat($baseStyle->getFormat());
+        }
         if (!$style->shouldApplyBackgroundColor() && $baseStyle->shouldApplyBackgroundColor()) {
             $styleToUpdate->setBackgroundColor($baseStyle->getBackgroundColor());
         }
diff --git a/src/Spout/Writer/Common/Manager/Style/StyleRegistry.php b/src/Spout/Writer/Common/Manager/Style/StyleRegistry.php
index fc978e7..d9e315f 100644
--- a/src/Spout/Writer/Common/Manager/Style/StyleRegistry.php
+++ b/src/Spout/Writer/Common/Manager/Style/StyleRegistry.php
@@ -37,7 +37,7 @@ class StyleRegistry
         $serializedStyle = $this->serialize($style);
 
         if (!$this->hasStyleAlreadyBeenRegistered($style)) {
-            $nextStyleId = count($this->serializedStyleToStyleIdMappingTable);
+            $nextStyleId = \count($this->serializedStyleToStyleIdMappingTable);
             $style->setId($nextStyleId);
 
             $this->serializedStyleToStyleIdMappingTable[$serializedStyle] = $nextStyleId;
@@ -79,7 +79,7 @@ class StyleRegistry
      */
     public function getRegisteredStyles()
     {
-        return array_values($this->styleIdToStyleMappingTable);
+        return \array_values($this->styleIdToStyleMappingTable);
     }
 
     /**
@@ -105,7 +105,7 @@ class StyleRegistry
         $currentId = $style->getId();
         $style->setId(0);
 
-        $serializedStyle = serialize($style);
+        $serializedStyle = \serialize($style);
 
         $style->setId($currentId);
 
diff --git a/src/Spout/Writer/Common/Manager/WorkbookManagerAbstract.php b/src/Spout/Writer/Common/Manager/WorkbookManagerAbstract.php
index e1b41bb..e49fc76 100644
--- a/src/Spout/Writer/Common/Manager/WorkbookManagerAbstract.php
+++ b/src/Spout/Writer/Common/Manager/WorkbookManagerAbstract.php
@@ -123,7 +123,7 @@ abstract class WorkbookManagerAbstract implements WorkbookManagerInterface
     {
         $worksheets = $this->getWorksheets();
 
-        $newSheetIndex = count($worksheets);
+        $newSheetIndex = \count($worksheets);
         $sheetManager = $this->managerFactory->createSheetManager();
         $sheet = $this->entityFactory->createSheet($newSheetIndex, $this->workbook->getInternalId(), $sheetManager);
 
@@ -272,7 +272,7 @@ abstract class WorkbookManagerAbstract implements WorkbookManagerInterface
         // update max num columns for the worksheet
         $currentMaxNumColumns = $worksheet->getMaxNumColumns();
         $cellsCount = $row->getNumCells();
-        $worksheet->setMaxNumColumns(max($currentMaxNumColumns, $cellsCount));
+        $worksheet->setMaxNumColumns(\max($currentMaxNumColumns, $cellsCount));
     }
 
     /**
diff --git a/src/Spout/Writer/Exception/Border/InvalidNameException.php b/src/Spout/Writer/Exception/Border/InvalidNameException.php
index 8bedc38..c975d4f 100644
--- a/src/Spout/Writer/Exception/Border/InvalidNameException.php
+++ b/src/Spout/Writer/Exception/Border/InvalidNameException.php
@@ -11,6 +11,6 @@ class InvalidNameException extends WriterException
     {
         $msg = '%s is not a valid name identifier for a border. Valid identifiers are: %s.';
 
-        parent::__construct(sprintf($msg, $name, implode(',', BorderPart::getAllowedNames())));
+        parent::__construct(\sprintf($msg, $name, \implode(',', BorderPart::getAllowedNames())));
     }
 }
diff --git a/src/Spout/Writer/Exception/Border/InvalidStyleException.php b/src/Spout/Writer/Exception/Border/InvalidStyleException.php
index e4bb145..2d1d78c 100644
--- a/src/Spout/Writer/Exception/Border/InvalidStyleException.php
+++ b/src/Spout/Writer/Exception/Border/InvalidStyleException.php
@@ -11,6 +11,6 @@ class InvalidStyleException extends WriterException
     {
         $msg = '%s is not a valid style identifier for a border. Valid identifiers are: %s.';
 
-        parent::__construct(sprintf($msg, $name, implode(',', BorderPart::getAllowedStyles())));
+        parent::__construct(\sprintf($msg, $name, \implode(',', BorderPart::getAllowedStyles())));
     }
 }
diff --git a/src/Spout/Writer/Exception/Border/InvalidWidthException.php b/src/Spout/Writer/Exception/Border/InvalidWidthException.php
index f38d898..790ddc2 100644
--- a/src/Spout/Writer/Exception/Border/InvalidWidthException.php
+++ b/src/Spout/Writer/Exception/Border/InvalidWidthException.php
@@ -11,6 +11,6 @@ class InvalidWidthException extends WriterException
     {
         $msg = '%s is not a valid width identifier for a border. Valid identifiers are: %s.';
 
-        parent::__construct(sprintf($msg, $name, implode(',', BorderPart::getAllowedWidths())));
+        parent::__construct(\sprintf($msg, $name, \implode(',', BorderPart::getAllowedWidths())));
     }
 }
diff --git a/src/Spout/Writer/ODS/Helper/BorderHelper.php b/src/Spout/Writer/ODS/Helper/BorderHelper.php
index a53f63c..34886ac 100644
--- a/src/Spout/Writer/ODS/Helper/BorderHelper.php
+++ b/src/Spout/Writer/ODS/Helper/BorderHelper.php
@@ -53,14 +53,14 @@ class BorderHelper
         $definition = 'fo:border-%s="%s"';
 
         if ($borderPart->getStyle() === Border::STYLE_NONE) {
-            $borderPartDefinition = sprintf($definition, $borderPart->getName(), 'none');
+            $borderPartDefinition = \sprintf($definition, $borderPart->getName(), 'none');
         } else {
             $attributes = [
                 self::$widthMap[$borderPart->getWidth()],
                 self::$styleMap[$borderPart->getStyle()],
                 '#' . $borderPart->getColor(),
             ];
-            $borderPartDefinition = sprintf($definition, $borderPart->getName(), implode(' ', $attributes));
+            $borderPartDefinition = \sprintf($definition, $borderPart->getName(), \implode(' ', $attributes));
         }
 
         return $borderPartDefinition;
diff --git a/src/Spout/Writer/ODS/Helper/FileSystemHelper.php b/src/Spout/Writer/ODS/Helper/FileSystemHelper.php
index d0e2e05..5598bb4 100644
--- a/src/Spout/Writer/ODS/Helper/FileSystemHelper.php
+++ b/src/Spout/Writer/ODS/Helper/FileSystemHelper.php
@@ -89,7 +89,7 @@ class FileSystemHelper extends \Box\Spout\Common\Helper\FileSystemHelper impleme
      */
     protected function createRootFolder()
     {
-        $this->rootFolder = $this->createFolder($this->baseFolderRealPath, uniqid('ods'));
+        $this->rootFolder = $this->createFolder($this->baseFolderRealPath, \uniqid('ods'));
 
         return $this;
     }
@@ -210,22 +210,22 @@ EOD;
 
         // Append sheets content to "content.xml"
         $contentXmlFilePath = $this->rootFolder . '/' . self::CONTENT_XML_FILE_NAME;
-        $contentXmlHandle = fopen($contentXmlFilePath, 'a');
+        $contentXmlHandle = \fopen($contentXmlFilePath, 'a');
 
         foreach ($worksheets as $worksheet) {
             // write the "<table:table>" node, with the final sheet's name
-            fwrite($contentXmlHandle, $worksheetManager->getTableElementStartAsString($worksheet));
+            \fwrite($contentXmlHandle, $worksheetManager->getTableElementStartAsString($worksheet));
 
             $worksheetFilePath = $worksheet->getFilePath();
             $this->copyFileContentsToTarget($worksheetFilePath, $contentXmlHandle);
 
-            fwrite($contentXmlHandle, '</table:table>');
+            \fwrite($contentXmlHandle, '</table:table>');
         }
 
         $contentXmlFileContents = '</office:spreadsheet></office:body></office:document-content>';
 
-        fwrite($contentXmlHandle, $contentXmlFileContents);
-        fclose($contentXmlHandle);
+        \fwrite($contentXmlHandle, $contentXmlFileContents);
+        \fclose($contentXmlHandle);
 
         return $this;
     }
@@ -241,9 +241,9 @@ EOD;
      */
     protected function copyFileContentsToTarget($sourceFilePath, $targetResource)
     {
-        $sourceHandle = fopen($sourceFilePath, 'r');
-        stream_copy_to_stream($sourceHandle, $targetResource);
-        fclose($sourceHandle);
+        $sourceHandle = \fopen($sourceFilePath, 'r');
+        \stream_copy_to_stream($sourceHandle, $targetResource);
+        \fclose($sourceHandle);
     }
 
     /**
diff --git a/src/Spout/Writer/ODS/Manager/OptionsManager.php b/src/Spout/Writer/ODS/Manager/OptionsManager.php
index 4d29928..a6fb564 100644
--- a/src/Spout/Writer/ODS/Manager/OptionsManager.php
+++ b/src/Spout/Writer/ODS/Manager/OptionsManager.php
@@ -42,7 +42,7 @@ class OptionsManager extends OptionsManagerAbstract
      */
     protected function setDefaultOptions()
     {
-        $this->setOption(Options::TEMP_FOLDER, sys_get_temp_dir());
+        $this->setOption(Options::TEMP_FOLDER, \sys_get_temp_dir());
         $this->setOption(Options::DEFAULT_ROW_STYLE, $this->styleBuilder->build());
         $this->setOption(Options::SHOULD_CREATE_NEW_SHEETS_AUTOMATICALLY, true);
     }
diff --git a/src/Spout/Writer/ODS/Manager/Style/StyleManager.php b/src/Spout/Writer/ODS/Manager/Style/StyleManager.php
index e563028..b0d75d8 100644
--- a/src/Spout/Writer/ODS/Manager/Style/StyleManager.php
+++ b/src/Spout/Writer/ODS/Manager/Style/StyleManager.php
@@ -3,6 +3,7 @@
 namespace Box\Spout\Writer\ODS\Manager\Style;
 
 use Box\Spout\Common\Entity\Style\BorderPart;
+use Box\Spout\Common\Entity\Style\CellAlignment;
 use Box\Spout\Writer\Common\Entity\Worksheet;
 use Box\Spout\Writer\Common\Manager\ManagesCellSize;
 use Box\Spout\Writer\ODS\Helper\BorderHelper;
@@ -215,6 +216,7 @@ EOD;
         $content = '<style:style style:data-style-name="N0" style:family="table-cell" style:name="ce' . $styleIndex . '" style:parent-style-name="Default">';
 
         $content .= $this->getTextPropertiesSectionContent($style);
+        $content .= $this->getParagraphPropertiesSectionContent($style);
         $content .= $this->getTableCellPropertiesSectionContent($style);
 
         $content .= '</style:style>';
@@ -230,26 +232,26 @@ EOD;
      */
     private function getTextPropertiesSectionContent($style)
     {
-        $content = '';
-
-        if ($style->shouldApplyFont()) {
-            $content .= $this->getFontSectionContent($style);
+        if (!$style->shouldApplyFont()) {
+            return '';
         }
 
-        return $content;
+        return '<style:text-properties '
+            . $this->getFontSectionContent($style)
+            . '/>';
     }
 
     /**
-     * Returns the contents of the "<style:text-properties>" section, inside "<style:style>" section
+     * Returns the contents of the fonts definition section, inside "<style:text-properties>" section
      *
      * @param \Box\Spout\Common\Entity\Style\Style $style
+     *
      * @return string
      */
     private function getFontSectionContent($style)
     {
         $defaultStyle = $this->getDefaultStyle();
-
-        $content = '<style:text-properties';
+        $content = '';
 
         $fontColor = $style->getFontColor();
         if ($fontColor !== $defaultStyle->getFontColor()) {
@@ -279,11 +281,60 @@ EOD;
             $content .= ' style:text-line-through-style="solid"';
         }
 
-        $content .= '/>';
-
         return $content;
     }
 
+    /**
+     * Returns the contents of the "<style:paragraph-properties>" section, inside "<style:style>" section
+     *
+     * @param \Box\Spout\Common\Entity\Style\Style $style
+     *
+     * @return string
+     */
+    private function getParagraphPropertiesSectionContent($style)
+    {
+        if (!$style->shouldApplyCellAlignment()) {
+            return '';
+        }
+
+        return '<style:paragraph-properties '
+            . $this->getCellAlignmentSectionContent($style)
+            . '/>';
+    }
+
+    /**
+     * Returns the contents of the cell alignment definition for the "<style:paragraph-properties>" section
+     *
+     * @param \Box\Spout\Common\Entity\Style\Style $style
+     *
+     * @return string
+     */
+    private function getCellAlignmentSectionContent($style)
+    {
+        return \sprintf(
+            ' fo:text-align="%s" ',
+            $this->transformCellAlignment($style->getCellAlignment())
+        );
+    }
+
+    /**
+     * Even though "left" and "right" alignments are part of the spec, and interpreted
+     * respectively as "start" and "end", using the recommended values increase compatibility
+     * with software that will read the created ODS file.
+     *
+     * @param string $cellAlignment
+     *
+     * @return string
+     */
+    private function transformCellAlignment($cellAlignment)
+    {
+        switch ($cellAlignment) {
+            case CellAlignment::LEFT: return 'start';
+            case CellAlignment::RIGHT: return 'end';
+            default: return $cellAlignment;
+        }
+    }
+
     /**
      * Returns the contents of the "<style:table-cell-properties>" section, inside "<style:style>" section
      *
@@ -292,7 +343,7 @@ EOD;
      */
     private function getTableCellPropertiesSectionContent($style)
     {
-        $content = '';
+        $content = '<style:table-cell-properties ';
 
         if ($style->shouldWrapText()) {
             $content .= $this->getWrapTextXMLContent();
@@ -306,6 +357,8 @@ EOD;
             $content .= $this->getBackgroundColorXMLContent($style);
         }
 
+        $content .= '/>';
+
         return $content;
     }
 
@@ -316,7 +369,7 @@ EOD;
      */
     private function getWrapTextXMLContent()
     {
-        return '<style:table-cell-properties fo:wrap-option="wrap" style:vertical-align="automatic"/>';
+        return ' fo:wrap-option="wrap" style:vertical-align="automatic" ';
     }
 
     /**
@@ -327,13 +380,11 @@ EOD;
      */
     private function getBorderXMLContent($style)
     {
-        $borderProperty = '<style:table-cell-properties %s />';
-
-        $borders = array_map(function (BorderPart $borderPart) {
+        $borders = \array_map(function (BorderPart $borderPart) {
             return BorderHelper::serializeBorderPart($borderPart);
         }, $style->getBorder()->getParts());
 
-        return sprintf($borderProperty, implode(' ', $borders));
+        return \sprintf(' %s ', \implode(' ', $borders));
     }
 
     /**
@@ -344,10 +395,7 @@ EOD;
      */
     private function getBackgroundColorXMLContent($style)
     {
-        return sprintf(
-            '<style:table-cell-properties fo:background-color="#%s"/>',
-            $style->getBackgroundColor()
-        );
+        return \sprintf(' fo:background-color="#%s" ', $style->getBackgroundColor());
     }
 
     public function getTableColumnStylesXMLContent(): string
diff --git a/src/Spout/Writer/ODS/Manager/Style/StyleRegistry.php b/src/Spout/Writer/ODS/Manager/Style/StyleRegistry.php
index bc9dccc..6c580d4 100644
--- a/src/Spout/Writer/ODS/Manager/Style/StyleRegistry.php
+++ b/src/Spout/Writer/ODS/Manager/Style/StyleRegistry.php
@@ -33,6 +33,6 @@ class StyleRegistry extends \Box\Spout\Writer\Common\Manager\Style\StyleRegistry
      */
     public function getUsedFonts()
     {
-        return array_keys($this->usedFontsSet);
+        return \array_keys($this->usedFontsSet);
     }
 }
diff --git a/src/Spout/Writer/ODS/Manager/WorkbookManager.php b/src/Spout/Writer/ODS/Manager/WorkbookManager.php
index 367c281..77c5f90 100644
--- a/src/Spout/Writer/ODS/Manager/WorkbookManager.php
+++ b/src/Spout/Writer/ODS/Manager/WorkbookManager.php
@@ -56,7 +56,7 @@ class WorkbookManager extends WorkbookManagerAbstract
     protected function writeAllFilesToDiskAndZipThem($finalFilePointer)
     {
         $worksheets = $this->getWorksheets();
-        $numWorksheets = count($worksheets);
+        $numWorksheets = \count($worksheets);
 
         $this->fileSystemHelper
             ->createContentFile($this->worksheetManager, $this->styleManager, $worksheets)
diff --git a/src/Spout/Writer/ODS/Manager/WorksheetManager.php b/src/Spout/Writer/ODS/Manager/WorksheetManager.php
index 6623d67..a114749 100644
--- a/src/Spout/Writer/ODS/Manager/WorksheetManager.php
+++ b/src/Spout/Writer/ODS/Manager/WorksheetManager.php
@@ -70,7 +70,7 @@ class WorksheetManager implements WorksheetManagerInterface
      */
     public function startSheet(Worksheet $worksheet)
     {
-        $sheetFilePointer = fopen($worksheet->getFilePath(), 'w');
+        $sheetFilePointer = \fopen($worksheet->getFilePath(), 'w');
         $this->throwIfSheetFilePointerIsNotAvailable($sheetFilePointer);
 
         $worksheet->setFilePointer($sheetFilePointer);
@@ -143,7 +143,7 @@ class WorksheetManager implements WorksheetManagerInterface
 
         $data .= '</table:table-row>';
 
-        $wasWriteSuccessful = fwrite($worksheet->getFilePointer(), $data);
+        $wasWriteSuccessful = \fwrite($worksheet->getFilePointer(), $data);
         if ($wasWriteSuccessful === false) {
             throw new IOException("Unable to write data in {$worksheet->getFilePath()}");
         }
@@ -199,7 +199,7 @@ class WorksheetManager implements WorksheetManagerInterface
         if ($cell->isString()) {
             $data .= ' office:value-type="string" calcext:value-type="string">';
 
-            $cellValueLines = explode("\n", $cell->getValue());
+            $cellValueLines = \explode("\n", $cell->getValue());
             foreach ($cellValueLines as $cellValueLine) {
                 $data .= '<text:p>' . $this->stringsEscaper->escape($cellValueLine) . '</text:p>';
             }
@@ -213,10 +213,15 @@ class WorksheetManager implements WorksheetManagerInterface
             $data .= ' office:value-type="float" calcext:value-type="float" office:value="' . $cell->getValue() . '">';
             $data .= '<text:p>' . $cell->getValue() . '</text:p>';
             $data .= '</table:table-cell>';
+        } elseif ($cell->isError() && is_string($cell->getValueEvenIfError())) {
+            // only writes the error value if it's a string
+            $data .= ' office:value-type="string" calcext:value-type="error" office:value="">';
+            $data .= '<text:p>' . $cell->getValueEvenIfError() . '</text:p>';
+            $data .= '</table:table-cell>';
         } elseif ($cell->isEmpty()) {
             $data .= '/>';
         } else {
-            throw new InvalidArgumentException('Trying to add a value with an unsupported type: ' . gettype($cell->getValue()));
+            throw new InvalidArgumentException('Trying to add a value with an unsupported type: ' . \gettype($cell->getValue()));
         }
 
         return $data;
@@ -232,11 +237,11 @@ class WorksheetManager implements WorksheetManagerInterface
     {
         $worksheetFilePointer = $worksheet->getFilePointer();
 
-        if (!is_resource($worksheetFilePointer)) {
+        if (!\is_resource($worksheetFilePointer)) {
             return;
         }
 
-        fclose($worksheetFilePointer);
+        \fclose($worksheetFilePointer);
     }
 
     /**
diff --git a/src/Spout/Writer/WriterAbstract.php b/src/Spout/Writer/WriterAbstract.php
index 4bcc407..d96a628 100644
--- a/src/Spout/Writer/WriterAbstract.php
+++ b/src/Spout/Writer/WriterAbstract.php
@@ -223,7 +223,7 @@ abstract class WriterAbstract implements WriterInterface
 
         $this->closeWriter();
 
-        if (is_resource($this->filePointer)) {
+        if (\is_resource($this->filePointer)) {
             $this->globalFunctionsHelper->fclose($this->filePointer);
         }
 
@@ -243,7 +243,7 @@ abstract class WriterAbstract implements WriterInterface
 
         // remove output file if it was created
         if ($this->globalFunctionsHelper->file_exists($this->outputFilePath)) {
-            $outputFolderPath = dirname($this->outputFilePath);
+            $outputFolderPath = \dirname($this->outputFilePath);
             $fileSystemHelper = $this->helperFactory->createFileSystemHelper($outputFolderPath);
             $fileSystemHelper->deleteFile($this->outputFilePath);
         }
diff --git a/src/Spout/Writer/XLSX/Helper/BorderHelper.php b/src/Spout/Writer/XLSX/Helper/BorderHelper.php
index 1c773fd..ed202cb 100644
--- a/src/Spout/Writer/XLSX/Helper/BorderHelper.php
+++ b/src/Spout/Writer/XLSX/Helper/BorderHelper.php
@@ -43,8 +43,8 @@ class BorderHelper
     {
         $borderStyle = self::getBorderStyle($borderPart);
 
-        $colorEl = $borderPart->getColor() ? sprintf('<color rgb="%s"/>', $borderPart->getColor()) : '';
-        $partEl = sprintf(
+        $colorEl = $borderPart->getColor() ? \sprintf('<color rgb="%s"/>', $borderPart->getColor()) : '';
+        $partEl = \sprintf(
             '<%s style="%s">%s</%s>',
             $borderPart->getName(),
             $borderStyle,
diff --git a/src/Spout/Writer/XLSX/Helper/FileSystemHelper.php b/src/Spout/Writer/XLSX/Helper/FileSystemHelper.php
index 8997b98..0a19d9e 100644
--- a/src/Spout/Writer/XLSX/Helper/FileSystemHelper.php
+++ b/src/Spout/Writer/XLSX/Helper/FileSystemHelper.php
@@ -112,7 +112,7 @@ class FileSystemHelper extends \Box\Spout\Common\Helper\FileSystemHelper impleme
      */
     private function createRootFolder()
     {
-        $this->rootFolder = $this->createFolder($this->baseFolderRealPath, uniqid('xlsx', true));
+        $this->rootFolder = $this->createFolder($this->baseFolderRealPath, \uniqid('xlsx', true));
 
         return $this;
     }
diff --git a/src/Spout/Writer/XLSX/Manager/OptionsManager.php b/src/Spout/Writer/XLSX/Manager/OptionsManager.php
index d83b8ae..e6adedb 100644
--- a/src/Spout/Writer/XLSX/Manager/OptionsManager.php
+++ b/src/Spout/Writer/XLSX/Manager/OptionsManager.php
@@ -55,7 +55,7 @@ class OptionsManager extends OptionsManagerAbstract
             ->setFontName(self::DEFAULT_FONT_NAME)
             ->build();
 
-        $this->setOption(Options::TEMP_FOLDER, sys_get_temp_dir());
+        $this->setOption(Options::TEMP_FOLDER, \sys_get_temp_dir());
         $this->setOption(Options::DEFAULT_ROW_STYLE, $defaultRowStyle);
         $this->setOption(Options::SHOULD_CREATE_NEW_SHEETS_AUTOMATICALLY, true);
         $this->setOption(Options::SHOULD_USE_INLINE_STRINGS, true);
diff --git a/src/Spout/Writer/XLSX/Manager/SharedStringsManager.php b/src/Spout/Writer/XLSX/Manager/SharedStringsManager.php
index 2a60c3c..b0a5b48 100644
--- a/src/Spout/Writer/XLSX/Manager/SharedStringsManager.php
+++ b/src/Spout/Writer/XLSX/Manager/SharedStringsManager.php
@@ -40,13 +40,13 @@ EOD;
     public function __construct($xlFolder, $stringsEscaper)
     {
         $sharedStringsFilePath = $xlFolder . '/' . self::SHARED_STRINGS_FILE_NAME;
-        $this->sharedStringsFilePointer = fopen($sharedStringsFilePath, 'w');
+        $this->sharedStringsFilePointer = \fopen($sharedStringsFilePath, 'w');
 
         $this->throwIfSharedStringsFilePointerIsNotAvailable();
 
         // the headers is split into different parts so that we can fseek and put in the correct count and uniqueCount later
         $header = self::SHARED_STRINGS_XML_FILE_FIRST_PART_HEADER . ' ' . self::DEFAULT_STRINGS_COUNT_PART . '>';
-        fwrite($this->sharedStringsFilePointer, $header);
+        \fwrite($this->sharedStringsFilePointer, $header);
 
         $this->stringsEscaper = $stringsEscaper;
     }
@@ -73,7 +73,7 @@ EOD;
      */
     public function writeString($string)
     {
-        fwrite($this->sharedStringsFilePointer, '<si><t xml:space="preserve">' . $this->stringsEscaper->escape($string) . '</t></si>');
+        \fwrite($this->sharedStringsFilePointer, '<si><t xml:space="preserve">' . $this->stringsEscaper->escape($string) . '</t></si>');
         $this->numSharedStrings++;
 
         // Shared string ID is zero-based
@@ -87,20 +87,20 @@ EOD;
      */
     public function close()
     {
-        if (!is_resource($this->sharedStringsFilePointer)) {
+        if (!\is_resource($this->sharedStringsFilePointer)) {
             return;
         }
 
-        fwrite($this->sharedStringsFilePointer, '</sst>');
+        \fwrite($this->sharedStringsFilePointer, '</sst>');
 
         // Replace the default strings count with the actual number of shared strings in the file header
-        $firstPartHeaderLength = strlen(self::SHARED_STRINGS_XML_FILE_FIRST_PART_HEADER);
-        $defaultStringsCountPartLength = strlen(self::DEFAULT_STRINGS_COUNT_PART);
+        $firstPartHeaderLength = \strlen(self::SHARED_STRINGS_XML_FILE_FIRST_PART_HEADER);
+        $defaultStringsCountPartLength = \strlen(self::DEFAULT_STRINGS_COUNT_PART);
 
         // Adding 1 to take into account the space between the last xml attribute and "count"
-        fseek($this->sharedStringsFilePointer, $firstPartHeaderLength + 1);
-        fwrite($this->sharedStringsFilePointer, sprintf("%-{$defaultStringsCountPartLength}s", 'count="' . $this->numSharedStrings . '" uniqueCount="' . $this->numSharedStrings . '"'));
+        \fseek($this->sharedStringsFilePointer, $firstPartHeaderLength + 1);
+        \fwrite($this->sharedStringsFilePointer, \sprintf("%-{$defaultStringsCountPartLength}s", 'count="' . $this->numSharedStrings . '" uniqueCount="' . $this->numSharedStrings . '"'));
 
-        fclose($this->sharedStringsFilePointer);
+        \fclose($this->sharedStringsFilePointer);
     }
 }
diff --git a/src/Spout/Writer/XLSX/Manager/Style/StyleManager.php b/src/Spout/Writer/XLSX/Manager/Style/StyleManager.php
index b98307a..f0ca9d9 100644
--- a/src/Spout/Writer/XLSX/Manager/Style/StyleManager.php
+++ b/src/Spout/Writer/XLSX/Manager/Style/StyleManager.php
@@ -33,7 +33,10 @@ class StyleManager extends \Box\Spout\Writer\Common\Manager\Style\StyleManager
         $associatedBorderId = $this->styleRegistry->getBorderIdForStyleId($styleId);
         $hasStyleCustomBorders = ($associatedBorderId !== null && $associatedBorderId !== 0);
 
-        return ($hasStyleCustomFill || $hasStyleCustomBorders);
+        $associatedFormatId = $this->styleRegistry->getFormatIdForStyleId($styleId);
+        $hasStyleCustomFormats = ($associatedFormatId !== null && $associatedFormatId !== 0);
+
+        return ($hasStyleCustomFill || $hasStyleCustomBorders || $hasStyleCustomFormats);
     }
 
     /**
@@ -48,6 +51,7 @@ class StyleManager extends \Box\Spout\Writer\Common\Manager\Style\StyleManager
 <styleSheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">
 EOD;
 
+        $content .= $this->getFormatsSectionContent();
         $content .= $this->getFontsSectionContent();
         $content .= $this->getFillsSectionContent();
         $content .= $this->getBordersSectionContent();
@@ -62,6 +66,35 @@ EOD;
         return $content;
     }
 
+    /**
+     * Returns the content of the "<numFmts>" section.
+     *
+     * @return string
+     */
+    protected function getFormatsSectionContent()
+    {
+        $tags = [];
+        $registeredFormats = $this->styleRegistry->getRegisteredFormats();
+        foreach ($registeredFormats as $styleId) {
+            $numFmtId = $this->styleRegistry->getFormatIdForStyleId($styleId);
+
+            //Built-in formats do not need to be declared, skip them
+            if ($numFmtId < 164) {
+                continue;
+            }
+
+            /** @var Style $style */
+            $style = $this->styleRegistry->getStyleFromStyleId($styleId);
+            $format = $style->getFormat();
+            $tags[] = '<numFmt numFmtId="' . $numFmtId . '" formatCode="' . $format . '"/>';
+        }
+        $content = '<numFmts count="' . \count($tags) . '">';
+        $content .= \implode('', $tags);
+        $content .= '</numFmts>';
+
+        return $content;
+    }
+
     /**
      * Returns the content of the "<fonts>" section.
      *
@@ -71,7 +104,7 @@ EOD;
     {
         $registeredStyles = $this->styleRegistry->getRegisteredStyles();
 
-        $content = '<fonts count="' . count($registeredStyles) . '">';
+        $content = '<fonts count="' . \count($registeredStyles) . '">';
 
         /** @var Style $style */
         foreach ($registeredStyles as $style) {
@@ -112,8 +145,8 @@ EOD;
         $registeredFills = $this->styleRegistry->getRegisteredFills();
 
         // Excel reserves two default fills
-        $fillsCount = count($registeredFills) + 2;
-        $content = sprintf('<fills count="%d">', $fillsCount);
+        $fillsCount = \count($registeredFills) + 2;
+        $content = \sprintf('<fills count="%d">', $fillsCount);
 
         $content .= '<fill><patternFill patternType="none"/></fill>';
         $content .= '<fill><patternFill patternType="gray125"/></fill>';
@@ -124,7 +157,7 @@ EOD;
             $style = $this->styleRegistry->getStyleFromStyleId($styleId);
 
             $backgroundColor = $style->getBackgroundColor();
-            $content .= sprintf(
+            $content .= \sprintf(
                 '<fill><patternFill patternType="solid"><fgColor rgb="%s"/></patternFill></fill>',
                 $backgroundColor
             );
@@ -145,7 +178,7 @@ EOD;
         $registeredBorders = $this->styleRegistry->getRegisteredBorders();
 
         // There is one default border with index 0
-        $borderCount = count($registeredBorders) + 1;
+        $borderCount = \count($registeredBorders) + 1;
 
         $content = '<borders count="' . $borderCount . '">';
 
@@ -200,24 +233,32 @@ EOD;
     {
         $registeredStyles = $this->styleRegistry->getRegisteredStyles();
 
-        $content = '<cellXfs count="' . count($registeredStyles) . '">';
+        $content = '<cellXfs count="' . \count($registeredStyles) . '">';
 
         foreach ($registeredStyles as $style) {
             $styleId = $style->getId();
             $fillId = $this->getFillIdForStyleId($styleId);
             $borderId = $this->getBorderIdForStyleId($styleId);
+            $numFmtId = $this->getFormatIdForStyleId($styleId);
 
-            $content .= '<xf numFmtId="0" fontId="' . $styleId . '" fillId="' . $fillId . '" borderId="' . $borderId . '" xfId="0"';
+            $content .= '<xf numFmtId="' . $numFmtId . '" fontId="' . $styleId . '" fillId="' . $fillId . '" borderId="' . $borderId . '" xfId="0"';
 
             if ($style->shouldApplyFont()) {
                 $content .= ' applyFont="1"';
             }
 
-            $content .= sprintf(' applyBorder="%d"', $style->shouldApplyBorder() ? 1 : 0);
+            $content .= \sprintf(' applyBorder="%d"', $style->shouldApplyBorder() ? 1 : 0);
 
-            if ($style->shouldWrapText()) {
+            if ($style->shouldApplyCellAlignment() || $style->shouldWrapText()) {
                 $content .= ' applyAlignment="1">';
-                $content .= '<alignment wrapText="1"/>';
+                $content .= '<alignment';
+                if ($style->shouldApplyCellAlignment()) {
+                    $content .= \sprintf(' horizontal="%s"', $style->getCellAlignment());
+                }
+                if ($style->shouldWrapText()) {
+                    $content .= ' wrapText="1"';
+                }
+                $content .= '/>';
                 $content .= '</xf>';
             } else {
                 $content .= '/>';
@@ -261,6 +302,22 @@ EOD;
         return $isDefaultStyle ? 0 : ($this->styleRegistry->getBorderIdForStyleId($styleId) ?: 0);
     }
 
+    /**
+     * Returns the format ID associated to the given style ID.
+     * For the default style use general format.
+     *
+     * @param int $styleId
+     * @return int
+     */
+    private function getFormatIdForStyleId($styleId)
+    {
+        // For the default style (ID = 0), we don't want to override the format.
+        // Otherwise all cells of the spreadsheet will have a format.
+        $isDefaultStyle = ($styleId === 0);
+
+        return $isDefaultStyle ? 0 : ($this->styleRegistry->getFormatIdForStyleId($styleId) ?: 0);
+    }
+
     /**
      * Returns the content of the "<cellStyles>" section.
      *
diff --git a/src/Spout/Writer/XLSX/Manager/Style/StyleRegistry.php b/src/Spout/Writer/XLSX/Manager/Style/StyleRegistry.php
index abd89f1..ace607c 100644
--- a/src/Spout/Writer/XLSX/Manager/Style/StyleRegistry.php
+++ b/src/Spout/Writer/XLSX/Manager/Style/StyleRegistry.php
@@ -10,6 +10,79 @@ use Box\Spout\Common\Entity\Style\Style;
  */
 class StyleRegistry extends \Box\Spout\Writer\Common\Manager\Style\StyleRegistry
 {
+    /**
+     * @see https://msdn.microsoft.com/en-us/library/ff529597(v=office.12).aspx
+     * @var array Mapping between built-in format and the associated numFmtId
+     */
+    protected static $builtinNumFormatToIdMapping = [
+        'General' => 0,
+        '0' => 1,
+        '0.00' => 2,
+        '#,##0' => 3,
+        '#,##0.00' => 4,
+        '$#,##0,\-$#,##0' => 5,
+        '$#,##0,[Red]\-$#,##0' => 6,
+        '$#,##0.00,\-$#,##0.00' => 7,
+        '$#,##0.00,[Red]\-$#,##0.00' => 8,
+        '0%' => 9,
+        '0.00%' => 10,
+        '0.00E+00' => 11,
+        '# ?/?' => 12,
+        '# ??/??' => 13,
+        'mm-dd-yy' => 14,
+        'd-mmm-yy' => 15,
+        'd-mmm' => 16,
+        'mmm-yy' => 17,
+        'h:mm AM/PM' => 18,
+        'h:mm:ss AM/PM' => 19,
+        'h:mm' => 20,
+        'h:mm:ss' => 21,
+        'm/d/yy h:mm' => 22,
+
+        '#,##0 ,(#,##0)' => 37,
+        '#,##0 ,[Red](#,##0)' => 38,
+        '#,##0.00,(#,##0.00)' => 39,
+        '#,##0.00,[Red](#,##0.00)' => 40,
+
+        '_("$"* #,##0.00_),_("$"* \(#,##0.00\),_("$"* "-"??_),_(@_)' => 44,
+        'mm:ss' => 45,
+        '[h]:mm:ss' => 46,
+        'mm:ss.0' => 47,
+
+        '##0.0E+0' => 48,
+        '@' => 49,
+
+        '[$-404]e/m/d' => 27,
+        'm/d/yy' => 30,
+        't0' => 59,
+        't0.00' => 60,
+        't#,##0' => 61,
+        't#,##0.00' => 62,
+        't0%' => 67,
+        't0.00%' => 68,
+        't# ?/?' => 69,
+        't# ??/??' => 70,
+    ];
+
+    /**
+     * @var array
+     */
+    protected $registeredFormats = [];
+
+    /**
+     * @var array [STYLE_ID] => [FORMAT_ID] maps a style to a format declaration
+     */
+    protected $styleIdToFormatsMappingTable = [];
+
+    /**
+     * If the numFmtId is lower than 0xA4 (164 in decimal)
+     * then it's a built-in number format.
+     * Since Excel is the dominant vendor - we play along here
+     *
+     * @var int The fill index counter for custom fills.
+     */
+    protected $formatIndex = 164;
+
     /**
      * @var array
      */
@@ -48,11 +121,52 @@ class StyleRegistry extends \Box\Spout\Writer\Common\Manager\Style\StyleRegistry
     {
         $registeredStyle = parent::registerStyle($style);
         $this->registerFill($registeredStyle);
+        $this->registerFormat($registeredStyle);
         $this->registerBorder($registeredStyle);
 
         return $registeredStyle;
     }
 
+    /**
+     * Register a format definition
+     *
+     * @param Style $style
+     */
+    protected function registerFormat(Style $style)
+    {
+        $styleId = $style->getId();
+
+        $format = $style->getFormat();
+        if ($format) {
+            $isFormatRegistered = isset($this->registeredFormats[$format]);
+
+            // We need to track the already registered format definitions
+            if ($isFormatRegistered) {
+                $registeredStyleId = $this->registeredFormats[$format];
+                $registeredFormatId = $this->styleIdToFormatsMappingTable[$registeredStyleId];
+                $this->styleIdToFormatsMappingTable[$styleId] = $registeredFormatId;
+            } else {
+                $this->registeredFormats[$format] = $styleId;
+
+                $id = self::$builtinNumFormatToIdMapping[$format] ?? $this->formatIndex++;
+                $this->styleIdToFormatsMappingTable[$styleId] = $id;
+            }
+        } else {
+            // The formatId maps a style to a format declaration
+            // When there is no format definition - we default to 0 ( General )
+            $this->styleIdToFormatsMappingTable[$styleId] = 0;
+        }
+    }
+
+    /**
+     * @param int $styleId
+     * @return int|null Format ID associated to the given style ID
+     */
+    public function getFormatIdForStyleId($styleId)
+    {
+        return $this->styleIdToFormatsMappingTable[$styleId] ?? null;
+    }
+
     /**
      * Register a fill definition
      *
@@ -107,7 +221,7 @@ class StyleRegistry extends \Box\Spout\Writer\Common\Manager\Style\StyleRegistry
 
         if ($style->shouldApplyBorder()) {
             $border = $style->getBorder();
-            $serializedBorder = serialize($border);
+            $serializedBorder = \serialize($border);
 
             $isBorderAlreadyRegistered = isset($this->registeredBorders[$serializedBorder]);
 
@@ -117,7 +231,7 @@ class StyleRegistry extends \Box\Spout\Writer\Common\Manager\Style\StyleRegistry
                 $this->styleIdToBorderMappingTable[$styleId] = $registeredBorderId;
             } else {
                 $this->registeredBorders[$serializedBorder] = $styleId;
-                $this->styleIdToBorderMappingTable[$styleId] = count($this->registeredBorders);
+                $this->styleIdToBorderMappingTable[$styleId] = \count($this->registeredBorders);
             }
         } else {
             // If no border should be applied - the mapping is the default border: 0
@@ -151,4 +265,12 @@ class StyleRegistry extends \Box\Spout\Writer\Common\Manager\Style\StyleRegistry
     {
         return $this->registeredBorders;
     }
+
+    /**
+     * @return array
+     */
+    public function getRegisteredFormats()
+    {
+        return $this->registeredFormats;
+    }
 }
diff --git a/src/Spout/Writer/XLSX/Manager/WorkbookManager.php b/src/Spout/Writer/XLSX/Manager/WorkbookManager.php
index 944516b..708208b 100644
--- a/src/Spout/Writer/XLSX/Manager/WorkbookManager.php
+++ b/src/Spout/Writer/XLSX/Manager/WorkbookManager.php
@@ -44,7 +44,7 @@ class WorkbookManager extends WorkbookManagerAbstract
     {
         $worksheetFilesFolder = $this->fileSystemHelper->getXlWorksheetsFolder();
 
-        return $worksheetFilesFolder . '/' . strtolower($sheet->getName()) . '.xml';
+        return $worksheetFilesFolder . '/' . \strtolower($sheet->getName()) . '.xml';
     }
 
     /**
diff --git a/src/Spout/Writer/XLSX/Manager/WorksheetManager.php b/src/Spout/Writer/XLSX/Manager/WorksheetManager.php
index 3c7208d..f85a051 100644
--- a/src/Spout/Writer/XLSX/Manager/WorksheetManager.php
+++ b/src/Spout/Writer/XLSX/Manager/WorksheetManager.php
@@ -116,12 +116,12 @@ EOD;
      */
     public function startSheet(Worksheet $worksheet)
     {
-        $sheetFilePointer = fopen($worksheet->getFilePath(), 'w');
+        $sheetFilePointer = \fopen($worksheet->getFilePath(), 'w');
         $this->throwIfSheetFilePointerIsNotAvailable($sheetFilePointer);
 
         $worksheet->setFilePointer($sheetFilePointer);
 
-        fwrite($sheetFilePointer, self::SHEET_XML_FILE_HEADER);
+        \fwrite($sheetFilePointer, self::SHEET_XML_FILE_HEADER);
     }
 
     /**
@@ -167,22 +167,21 @@ EOD;
             fwrite($sheetFilePointer, $this->getXMLFragmentForColumnWidths());
             fwrite($sheetFilePointer, '<sheetData>');
         }
-        $cellIndex = 0;
+
         $rowStyle = $row->getStyle();
-        $rowIndex = $worksheet->getLastWrittenRowIndex() + 1;
+        $rowIndexOneBased = $worksheet->getLastWrittenRowIndex() + 1;
         $numCells = $row->getNumCells();
 
         $hasCustomHeight = $this->defaultRowHeight > 0 ? '1' : '0';
-        $rowXML = "<row r=\"{$rowIndex}\" spans=\"1:{$numCells}\" customHeight=\"{$hasCustomHeight}\">";
+        $rowXML = "<row r=\"{$rowIndexOneBased}\" spans=\"1:{$numCells}\" customHeight=\"{$hasCustomHeight}\">";
 
-        foreach ($row->getCells() as $cell) {
-            $rowXML .= $this->applyStyleAndGetCellXML($cell, $rowStyle, $rowIndex, $cellIndex);
-            $cellIndex++;
+        foreach ($row->getCells() as $columnIndexZeroBased => $cell) {
+            $rowXML .= $this->applyStyleAndGetCellXML($cell, $rowStyle, $rowIndexOneBased, $columnIndexZeroBased);
         }
 
         $rowXML .= '</row>';
 
-        $wasWriteSuccessful = fwrite($sheetFilePointer, $rowXML);
+        $wasWriteSuccessful = \fwrite($sheetFilePointer, $rowXML);
         if ($wasWriteSuccessful === false) {
             throw new IOException("Unable to write data in {$worksheet->getFilePath()}");
         }
@@ -193,14 +192,15 @@ EOD;
      * Applies styles to the given style, merging the cell's style with its row's style
      * Then builds and returns xml for the cell.
      *
-     * @param Cell $cell
+     * @param Cell  $cell
      * @param Style $rowStyle
-     * @param int $rowIndex
-     * @param int $cellIndex
+     * @param int   $rowIndexOneBased
+     * @param int   $columnIndexZeroBased
+     *
      * @return string
      * @throws InvalidArgumentException If the given value cannot be processed
      */
-    private function applyStyleAndGetCellXML(Cell $cell, Style $rowStyle, $rowIndex, $cellIndex)
+    private function applyStyleAndGetCellXML(Cell $cell, Style $rowStyle, $rowIndexOneBased, $columnIndexZeroBased)
     {
         // Apply row and extra styles
         $mergedCellAndRowStyle = $this->styleMerger->merge($cell->getStyle(), $rowStyle);
@@ -209,23 +209,24 @@ EOD;
 
         $registeredStyle = $this->styleManager->registerStyle($newCellStyle);
 
-        return $this->getCellXML($rowIndex, $cellIndex, $cell, $registeredStyle->getId());
+        return $this->getCellXML($rowIndexOneBased, $columnIndexZeroBased, $cell, $registeredStyle->getId());
     }
 
     /**
      * Builds and returns xml for a single cell.
      *
-     * @param int $rowIndex
-     * @param int $cellNumber
+     * @param int  $rowIndexOneBased
+     * @param int  $columnIndexZeroBased
      * @param Cell $cell
-     * @param int $styleId
+     * @param int  $styleId
+     *
      * @return string
      * @throws InvalidArgumentException If the given value cannot be processed
      */
-    private function getCellXML($rowIndex, $cellNumber, Cell $cell, $styleId)
+    private function getCellXML($rowIndexOneBased, $columnIndexZeroBased, Cell $cell, $styleId)
     {
-        $columnIndex = CellHelper::getCellIndexFromColumnIndex($cellNumber);
-        $cellXML = '<c r="' . $columnIndex . $rowIndex . '"';
+        $columnLetters = CellHelper::getColumnLettersFromColumnIndex($columnIndexZeroBased);
+        $cellXML = '<c r="' . $columnLetters . $rowIndexOneBased . '"';
         $cellXML .= ' s="' . $styleId . '"';
 
         if ($cell->isString()) {
@@ -234,6 +235,9 @@ EOD;
             $cellXML .= ' t="b"><v>' . (int)($cell->getValue()) . '</v></c>';
         } elseif ($cell->isNumeric()) {
             $cellXML .= '><v>' . $cell->getValue() . '</v></c>';
+        } elseif ($cell->isError() && is_string($cell->getValueEvenIfError())) {
+            // only writes the error value if it's a string
+            $cellXML .= ' t="e"><v>' . $cell->getValueEvenIfError() . '</v></c>';
         } elseif ($cell->isEmpty()) {
             if ($this->styleManager->shouldApplyStyleOnEmptyCell($styleId)) {
                 $cellXML .= '/>';
@@ -243,7 +247,7 @@ EOD;
                 $cellXML = '';
             }
         } else {
-            throw new InvalidArgumentException('Trying to add a value with an unsupported type: ' . gettype($cell->getValue()));
+            throw new InvalidArgumentException('Trying to add a value with an unsupported type: ' . \gettype($cell->getValue()));
         }
 
         return $cellXML;
@@ -314,14 +318,14 @@ EOD;
     {
         $worksheetFilePointer = $worksheet->getFilePointer();
 
-        if (!is_resource($worksheetFilePointer)) {
+        if (!\is_resource($worksheetFilePointer)) {
             return;
         }
 
         if ($this->hasWrittenRows) {
-            fwrite($worksheetFilePointer, '</sheetData>');
+            \fwrite($worksheetFilePointer, '</sheetData>');
         }
-        fwrite($worksheetFilePointer, '</worksheet>');
-        fclose($worksheetFilePointer);
+        \fwrite($worksheetFilePointer, '</worksheet>');
+        \fclose($worksheetFilePointer);
     }
 }
diff --git a/tests/Spout/Common/Entity/RowTest.php b/tests/Spout/Common/Entity/RowTest.php
index 2325412..095025c 100644
--- a/tests/Spout/Common/Entity/RowTest.php
+++ b/tests/Spout/Common/Entity/RowTest.php
@@ -78,10 +78,24 @@ class RowTest extends \PHPUnit\Framework\TestCase
         $row = new Row([], null);
         $cellMock = $this->getCellMock();
         $row->setCellAtIndex($cellMock, 3);
+
         $this->assertEquals($cellMock, $row->getCellAtIndex(3));
         $this->assertNull($row->getCellAtIndex(10));
     }
 
+    /**
+     * @return void
+     */
+    public function testSetCellAtIndex()
+    {
+        $row = new Row([], null);
+        $cellMock = $this->getCellMock();
+        $row->setCellAtIndex($cellMock, 1);
+
+        $this->assertEquals(2, $row->getNumCells());
+        $this->assertNull($row->getCellAtIndex(0));
+    }
+
     /**
      * @return void
      */
diff --git a/tests/Spout/Reader/ODS/ReaderTest.php b/tests/Spout/Reader/ODS/ReaderTest.php
index 674e4b0..ce56e4b 100644
--- a/tests/Spout/Reader/ODS/ReaderTest.php
+++ b/tests/Spout/Reader/ODS/ReaderTest.php
@@ -277,6 +277,17 @@ class ReaderTest extends TestCase
         $this->assertEquals([$expectedRow], $allRows);
     }
 
+    /**
+     * @return void
+     */
+    public function testReadShouldSupportWhitespaceAsXML()
+    {
+        $allRows = $this->getAllRowsForFile('sheet_with_whitespaces_as_xml.ods');
+
+        $expectedRow = ["Lorem  ipsum\tdolor sit amet"];
+        $this->assertEquals([$expectedRow], $allRows);
+    }
+
     /**
      * @NOTE: The LIBXML_NOENT is used to ACTUALLY substitute entities (and should therefore not be used)
      *
diff --git a/tests/Spout/Writer/Common/Creator/StyleBuilderTest.php b/tests/Spout/Writer/Common/Creator/StyleBuilderTest.php
index afa1a72..e1eb00f 100644
--- a/tests/Spout/Writer/Common/Creator/StyleBuilderTest.php
+++ b/tests/Spout/Writer/Common/Creator/StyleBuilderTest.php
@@ -3,7 +3,9 @@
 namespace Box\Spout\Writer\Common\Creator\Style;
 
 use Box\Spout\Common\Entity\Style\Border;
+use Box\Spout\Common\Entity\Style\CellAlignment;
 use Box\Spout\Common\Entity\Style\Color;
+use Box\Spout\Common\Exception\InvalidArgumentException;
 use Box\Spout\Writer\Common\Manager\Style\StyleMerger;
 use PHPUnit\Framework\TestCase;
 
@@ -41,4 +43,22 @@ class StyleBuilderTest extends TestCase
         $this->assertInstanceOf(Border::class, $baseStyle->getBorder(), 'Base style has a border');
         $this->assertInstanceOf(Border::class, $mergedStyle->getBorder(), 'Merged style has a border');
     }
+
+    /**
+     * @return void
+     */
+    public function testStyleBuilderShouldApplyCellAlignment()
+    {
+        $style = (new StyleBuilder())->setCellAlignment(CellAlignment::CENTER)->build();
+        $this->assertTrue($style->shouldApplyCellAlignment());
+    }
+
+    /**
+     * @return void
+     */
+    public function testStyleBuilderShouldThrowOnInvalidCellAlignment()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        (new StyleBuilder())->setCellAlignment('invalid_cell_alignment')->build();
+    }
 }
diff --git a/tests/Spout/Writer/Common/Helper/CellHelperTest.php b/tests/Spout/Writer/Common/Helper/CellHelperTest.php
index d699bc0..3ab9a79 100644
--- a/tests/Spout/Writer/Common/Helper/CellHelperTest.php
+++ b/tests/Spout/Writer/Common/Helper/CellHelperTest.php
@@ -12,7 +12,7 @@ class CellHelperTest extends TestCase
     /**
      * @return array
      */
-    public function dataProviderForTestGetCellIndexFromColumnIndex()
+    public function dataProviderForTestGetColumnLettersFromColumnIndex()
     {
         return [
             [0, 'A'],
@@ -24,14 +24,15 @@ class CellHelperTest extends TestCase
     }
 
     /**
-     * @dataProvider dataProviderForTestGetCellIndexFromColumnIndex
+     * @dataProvider dataProviderForTestGetColumnLettersFromColumnIndex
+     *
+     * @param int    $columnIndex
+     * @param string $expectedColumnLetters
      *
-     * @param int $columnIndex
-     * @param string $expectedCellIndex
      * @return void
      */
-    public function testGetCellIndexFromColumnIndex($columnIndex, $expectedCellIndex)
+    public function testGetColumnLettersFromColumnIndex($columnIndex, $expectedColumnLetters)
     {
-        $this->assertEquals($expectedCellIndex, CellHelper::getCellIndexFromColumnIndex($columnIndex));
+        $this->assertEquals($expectedColumnLetters, CellHelper::getColumnLettersFromColumnIndex($columnIndex));
     }
 }
diff --git a/tests/Spout/Writer/Common/Manager/Style/StyleMergerTest.php b/tests/Spout/Writer/Common/Manager/Style/StyleMergerTest.php
index 125d676..46820c0 100644
--- a/tests/Spout/Writer/Common/Manager/Style/StyleMergerTest.php
+++ b/tests/Spout/Writer/Common/Manager/Style/StyleMergerTest.php
@@ -45,6 +45,7 @@ class StyleMergerTest extends TestCase
                         ->setFontBold()
                         ->setFontColor(Color::YELLOW)
                         ->setBackgroundColor(Color::BLUE)
+                        ->setFormat('0.00')
                         ->build();
         $currentStyle = (new StyleBuilder())->setFontName('Font')->setFontUnderline()->build();
         $mergedStyle = $this->styleMerger->merge($currentStyle, $baseStyle);
@@ -60,6 +61,7 @@ class StyleMergerTest extends TestCase
         $this->assertTrue($mergedStyle->isFontUnderline());
         $this->assertEquals(Color::YELLOW, $mergedStyle->getFontColor());
         $this->assertEquals(Color::BLUE, $mergedStyle->getBackgroundColor());
+        $this->assertEquals('0.00', $mergedStyle->getFormat());
     }
 
     /**
diff --git a/tests/Spout/Writer/ODS/WriterTest.php b/tests/Spout/Writer/ODS/WriterTest.php
index 05c4930..b30a8f6 100644
--- a/tests/Spout/Writer/ODS/WriterTest.php
+++ b/tests/Spout/Writer/ODS/WriterTest.php
@@ -2,6 +2,7 @@
 
 namespace Box\Spout\Writer\ODS;
 
+use Box\Spout\Common\Entity\Cell;
 use Box\Spout\Common\Entity\Row;
 use Box\Spout\Common\Exception\InvalidArgumentException;
 use Box\Spout\Common\Exception\IOException;
@@ -321,6 +322,24 @@ class WriterTest extends TestCase
         }
     }
 
+    /**
+     * @return void
+     */
+    public function testAddRowShouldSupportCellInError()
+    {
+        $fileName = 'test_add_row_should_support_cell_in_error.ods';
+
+        $cell = WriterEntityFactory::createCell('#DIV/0');
+        $cell->setType(Cell::TYPE_ERROR);
+
+        $row = WriterEntityFactory::createRow([$cell]);
+
+        $this->writeToODSFile([$row], $fileName);
+
+        $this->assertValueWasWritten($fileName, 'calcext:value-type="error"');
+        $this->assertValueWasWritten($fileName, '<text:p>#DIV/0</text:p>');
+    }
+
     /**
      * @return void
      */
diff --git a/tests/Spout/Writer/ODS/WriterWithStyleTest.php b/tests/Spout/Writer/ODS/WriterWithStyleTest.php
index 5afd73b..dcdd364 100644
--- a/tests/Spout/Writer/ODS/WriterWithStyleTest.php
+++ b/tests/Spout/Writer/ODS/WriterWithStyleTest.php
@@ -4,6 +4,7 @@ namespace Box\Spout\Writer\ODS;
 
 use Box\Spout\Common\Entity\Row;
 use Box\Spout\Common\Entity\Style\Border;
+use Box\Spout\Common\Entity\Style\CellAlignment;
 use Box\Spout\Common\Entity\Style\Color;
 use Box\Spout\Common\Entity\Style\Style;
 use Box\Spout\Reader\Wrapper\XMLReader;
@@ -204,6 +205,25 @@ class WriterWithStyleTest extends TestCase
         $this->assertFirstChildHasAttributeEquals('wrap', $customStyleElement, 'table-cell-properties', 'fo:wrap-option');
     }
 
+    /**
+     * @return void
+     */
+    public function testAddRowShouldApplyCellAlignment()
+    {
+        $fileName = 'test_add_row_should_apply_cell_alignment.xlsx';
+
+        $rightAlignedStyle = (new StyleBuilder())->setCellAlignment(CellAlignment::RIGHT)->build();
+        $dataRows = $this->createStyledRowsFromValues([['ods--11']], $rightAlignedStyle);
+
+        $this->writeToODSFile($dataRows, $fileName);
+
+        $styleElements = $this->getCellStyleElementsFromContentXmlFile($fileName);
+        $this->assertCount(2, $styleElements, 'There should be 2 styles (default and custom)');
+
+        $customStyleElement = $styleElements[1];
+        $this->assertFirstChildHasAttributeEquals('end', $customStyleElement, 'paragraph-properties', 'fo:text-align');
+    }
+
     /**
      * @return void
      */
diff --git a/tests/Spout/Writer/XLSX/Manager/Style/StyleRegistryTest.php b/tests/Spout/Writer/XLSX/Manager/Style/StyleRegistryTest.php
index 6478a7c..6df6e8c 100644
--- a/tests/Spout/Writer/XLSX/Manager/Style/StyleRegistryTest.php
+++ b/tests/Spout/Writer/XLSX/Manager/Style/StyleRegistryTest.php
@@ -58,20 +58,50 @@ class StyleRegistryTest extends TestCase
         $borderRight = (new BorderBuilder())->setBorderRight()->build();
 
         $styleBorderLeft = (new StyleBuilder())->setBorder($borderLeft)->build();
-        $styleBoderRight = (new StyleBuilder())->setBorder($borderRight)->build();
-        $styleBoderRightBold = (new StyleBuilder())->setBorder($borderRight)->setFontBold()->build();
+        $styleBorderRight = (new StyleBuilder())->setBorder($borderRight)->build();
+        $styleBorderRightBold = (new StyleBuilder())->setBorder($borderRight)->setFontBold()->build();
         $styleNoBorder = (new StyleBuilder())->setFontItalic()->build();
 
         $styleRegistry->registerStyle($styleBorderLeft);
-        $styleRegistry->registerStyle($styleBoderRight);
-        $styleRegistry->registerStyle($styleBoderRightBold);
+        $styleRegistry->registerStyle($styleBorderRight);
+        $styleRegistry->registerStyle($styleBorderRightBold);
         $styleRegistry->registerStyle($styleNoBorder);
 
         $this->assertCount(2, $styleRegistry->getRegisteredBorders(), 'There should be 2 registered borders');
 
         $this->assertEquals(1, $styleRegistry->getBorderIdForStyleId($styleBorderLeft->getId()), 'First style with border set should have index 1 (0 is for the default style)');
-        $this->assertEquals(2, $styleRegistry->getBorderIdForStyleId($styleBoderRight->getId()), 'Second style with border set - different from first style - should have index 2');
-        $this->assertEquals(2, $styleRegistry->getBorderIdForStyleId($styleBoderRightBold->getId()), 'Style with border already set should have the same index');
+        $this->assertEquals(2, $styleRegistry->getBorderIdForStyleId($styleBorderRight->getId()), 'Second style with border set - different from first style - should have index 2');
+        $this->assertEquals(2, $styleRegistry->getBorderIdForStyleId($styleBorderRightBold->getId()), 'Style with border already set should have the same index');
         $this->assertEquals(0, $styleRegistry->getBorderIdForStyleId($styleNoBorder->getId()), 'Style with no border should have index 0');
     }
+
+    /**
+     * @return void
+     */
+    public function testRegisterStyleAlsoRegistersFormats()
+    {
+        $styleRegistry = $this->getStyleRegistry();
+
+        $styleBuiltinFormat = (new StyleBuilder())
+            ->setFontBold()
+            ->setFormat('0.00')//Builtin format
+            ->build();
+
+        $styleUserFormat = (new StyleBuilder())
+            ->setFontBold()
+            ->setFormat('0.000')
+            ->build();
+        $styleNoFormat = (new StyleBuilder())->setFontItalic()->build();
+
+        $styleRegistry->registerStyle($styleBuiltinFormat);
+        $styleRegistry->registerStyle($styleUserFormat);
+        $styleRegistry->registerStyle($styleNoFormat);
+
+        $this->assertCount(2, $styleRegistry->getRegisteredFormats(), 'There should be 2 registered formats');
+
+        $this->assertEquals(2, $styleRegistry->getFormatIdForStyleId($styleBuiltinFormat->getId()), 'First style with builtin format set should have index 2 (0 is for the default style)');
+        $this->assertEquals(164, $styleRegistry->getFormatIdForStyleId($styleUserFormat->getId()), 'Second style with user format set should have index 164 (0 is for the default style)');
+
+        $this->assertEquals(0, $styleRegistry->getFormatIdForStyleId($styleNoFormat->getId()), 'Style with no format should have index 0');
+    }
 }
diff --git a/tests/Spout/Writer/XLSX/WriterTest.php b/tests/Spout/Writer/XLSX/WriterTest.php
index d8a4768..15cc4e4 100644
--- a/tests/Spout/Writer/XLSX/WriterTest.php
+++ b/tests/Spout/Writer/XLSX/WriterTest.php
@@ -2,6 +2,7 @@
 
 namespace Box\Spout\Writer\XLSX;
 
+use Box\Spout\Common\Entity\Cell;
 use Box\Spout\Common\Entity\Row;
 use Box\Spout\Common\Exception\InvalidArgumentException;
 use Box\Spout\Common\Exception\IOException;
@@ -375,6 +376,23 @@ class WriterTest extends TestCase
         $this->assertInlineDataWasWrittenToSheet($fileName, 1, 10.2);
     }
 
+    /**
+     * @return void
+     */
+    public function testAddRowShouldSupportCellInError()
+    {
+        $fileName = 'test_add_row_should_support_cell_in_error.xlsx';
+
+        $cell = WriterEntityFactory::createCell('#DIV/0');
+        $cell->setType(Cell::TYPE_ERROR);
+
+        $row = WriterEntityFactory::createRow([$cell]);
+
+        $this->writeToXLSXFile([$row], $fileName);
+
+        $this->assertInlineDataWasWrittenToSheet($fileName, 1, 't="e"><v>#DIV/0</v>');
+    }
+
     /**
      * @return void
      */
diff --git a/tests/Spout/Writer/XLSX/WriterWithStyleTest.php b/tests/Spout/Writer/XLSX/WriterWithStyleTest.php
index 02e6d11..da0aec2 100644
--- a/tests/Spout/Writer/XLSX/WriterWithStyleTest.php
+++ b/tests/Spout/Writer/XLSX/WriterWithStyleTest.php
@@ -4,6 +4,7 @@ namespace Box\Spout\Writer\XLSX;
 
 use Box\Spout\Common\Entity\Row;
 use Box\Spout\Common\Entity\Style\Border;
+use Box\Spout\Common\Entity\Style\CellAlignment;
 use Box\Spout\Common\Entity\Style\Color;
 use Box\Spout\Common\Entity\Style\Style;
 use Box\Spout\Reader\Wrapper\XMLReader;
@@ -210,6 +211,43 @@ class WriterWithStyleTest extends TestCase
         $this->assertEquals('1', $cellDomElements[1]->getAttribute('s'));
     }
 
+    /**
+     * @return void
+     */
+    public function testAddRowWithNumFmtStyles()
+    {
+        $fileName = 'test_add_row_with_numfmt.xlsx';
+        $style = (new StyleBuilder())
+            ->setFontBold()
+            ->setFormat('0.00')//Builtin format
+            ->build();
+        $style2 = (new StyleBuilder())
+            ->setFontBold()
+            ->setFormat('0.000')
+            ->build();
+
+        $dataRows = [
+            $this->createStyledRowFromValues([1.123456789], $style),
+            $this->createStyledRowFromValues([12.1], $style2),
+        ];
+
+        $this->writeToXLSXFile($dataRows, $fileName);
+
+        $formatsDomElement = $this->getXmlSectionFromStylesXmlFile($fileName, 'numFmts');
+        $this->assertEquals(
+            1,
+            $formatsDomElement->getAttribute('count'),
+            'There should be 2 formats, including the default one'
+        );
+
+        $cellXfsDomElement = $this->getXmlSectionFromStylesXmlFile($fileName, 'cellXfs');
+
+        foreach ([2, 164] as $index => $expected) {
+            $xfElement = $cellXfsDomElement->getElementsByTagName('xf')->item($index + 1);
+            $this->assertEquals($expected, $xfElement->getAttribute('numFmtId'));
+        }
+    }
+
     /**
      * @return void
      */
@@ -250,6 +288,24 @@ class WriterWithStyleTest extends TestCase
         $this->assertFirstChildHasAttributeEquals('1', $xfElement, 'alignment', 'wrapText');
     }
 
+    /**
+     * @return void
+     */
+    public function testAddRowShouldApplyCellAlignment()
+    {
+        $fileName = 'test_add_row_should_apply_cell_alignment.xlsx';
+
+        $rightAlignedStyle = (new StyleBuilder())->setCellAlignment(CellAlignment::RIGHT)->build();
+        $dataRows = $this->createStyledRowsFromValues([['xlsx--11']], $rightAlignedStyle);
+
+        $this->writeToXLSXFile($dataRows, $fileName);
+
+        $cellXfsDomElement = $this->getXmlSectionFromStylesXmlFile($fileName, 'cellXfs');
+        $xfElement = $cellXfsDomElement->getElementsByTagName('xf')->item(1);
+        $this->assertEquals(1, $xfElement->getAttribute('applyAlignment'));
+        $this->assertFirstChildHasAttributeEquals(CellAlignment::RIGHT, $xfElement, 'alignment', 'horizontal');
+    }
+
     /**
      * @return void
      */
diff --git a/tests/resources/ods/sheet_with_whitespaces_as_xml.ods b/tests/resources/ods/sheet_with_whitespaces_as_xml.ods
new file mode 100644
index 0000000..d345951
Binary files /dev/null and b/tests/resources/ods/sheet_with_whitespaces_as_xml.ods differ