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<div class="section" id="common-functions">
<h1>Common Functions<a class="headerlink" href="#common-functions" title="Permalink to this headline">¶</a></h1>
<p>CodeIgniter uses a few functions for its operation that are globally
defined, and are available to you at any point. These do not require
loading any libraries or helpers.</p>
<div class="custom-index container"></div><dl class="function">
<dt id="is_php">
<code class="descname">is_php</code><span class="sig-paren">(</span><em>$version</em><span class="sig-paren">)</span><a class="headerlink" href="#is_php" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$version</strong> (<em>string</em>) – Version number</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">TRUE if the running PHP version is at least the one specified or FALSE if not</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">bool</p>
</td>
</tr>
</tbody>
</table>
<p>Determines if the PHP version being used is greater than the
supplied version number.</p>
<p>Example:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="nx">is_php</span><span class="p">(</span><span class="s1">'5.3'</span><span class="p">))</span>
<span class="p">{</span>
<span class="nv">$str</span> <span class="o">=</span> <span class="nb">quoted_printable_encode</span><span class="p">(</span><span class="nv">$str</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Returns boolean TRUE if the installed version of PHP is equal to or
greater than the supplied version number. Returns FALSE if the installed
version of PHP is lower than the supplied version number.</p>
</dd></dl>
<dl class="function">
<dt id="is_really_writable">
<code class="descname">is_really_writable</code><span class="sig-paren">(</span><em>$file</em><span class="sig-paren">)</span><a class="headerlink" href="#is_really_writable" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$file</strong> (<em>string</em>) – File path</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">TRUE if the path is writable, FALSE if not</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">bool</p>
</td>
</tr>
</tbody>
</table>
<p><code class="docutils literal"><span class="pre">is_writable()</span></code> returns TRUE on Windows servers when you really can’t
write to the file as the OS reports to PHP as FALSE only if the
read-only attribute is marked.</p>
<p>This function determines if a file is actually writable by attempting
to write to it first. Generally only recommended on platforms where
this information may be unreliable.</p>
<p>Example:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="nx">is_really_writable</span><span class="p">(</span><span class="s1">'file.txt'</span><span class="p">))</span>
<span class="p">{</span>
<span class="k">echo</span> <span class="s2">"I could write to this if I wanted to"</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">else</span>
<span class="p">{</span>
<span class="k">echo</span> <span class="s2">"File is not writable"</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">See also <a class="reference external" href="https://bugs.php.net/bug.php?id=54709">PHP bug #54709</a> for more info.</p>
</div>
</dd></dl>
<dl class="function">
<dt id="config_item">
<code class="descname">config_item</code><span class="sig-paren">(</span><em>$key</em><span class="sig-paren">)</span><a class="headerlink" href="#config_item" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$key</strong> (<em>string</em>) – Config item key</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Configuration key value or NULL if not found</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">mixed</p>
</td>
</tr>
</tbody>
</table>
<p>The <a class="reference internal" href="../libraries/config.html"><span class="doc">Config Library</span></a> is the preferred way of
accessing configuration information, however <code class="docutils literal"><span class="pre">config_item()</span></code> can be used
to retrieve single keys. See <a class="reference internal" href="../libraries/config.html"><span class="doc">Config Library</span></a>
documentation for more information.</p>
</dd></dl>
<dl class="function">
<dt id="set_status_header">
<code class="descname">set_status_header</code><span class="sig-paren">(</span><em>$code</em><span class="optional">[</span>, <em>$text = ''</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#set_status_header" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$code</strong> (<em>int</em>) – HTTP Response status code</li>
<li><strong>$text</strong> (<em>string</em>) – A custom message to set with the status code</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">void</p>
</td>
</tr>
</tbody>
</table>
<p>Permits you to manually set a server status header. Example:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nx">set_status_header</span><span class="p">(</span><span class="mi">401</span><span class="p">);</span>
<span class="c1">// Sets the header as: Unauthorized</span>
</pre></div>
</div>
<p><a class="reference external" href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html">See here</a> for
a full list of headers.</p>
</dd></dl>
<dl class="function">
<dt id="remove_invisible_characters">
<code class="descname">remove_invisible_characters</code><span class="sig-paren">(</span><em>$str</em><span class="optional">[</span>, <em>$url_encoded = TRUE</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#remove_invisible_characters" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$str</strong> (<em>string</em>) – Input string</li>
<li><strong>$url_encoded</strong> (<em>bool</em>) – Whether to remove URL-encoded characters as well</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Sanitized string</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>This function prevents inserting NULL characters between ASCII
characters, like Java\0script.</p>
<p>Example:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nx">remove_invisible_characters</span><span class="p">(</span><span class="s1">'Java\\0script'</span><span class="p">);</span>
<span class="c1">// Returns: 'Javascript'</span>
</pre></div>
</div>
</dd></dl>
<dl class="function">
<dt id="html_escape">
<code class="descname">html_escape</code><span class="sig-paren">(</span><em>$var</em><span class="sig-paren">)</span><a class="headerlink" href="#html_escape" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$var</strong> (<em>mixed</em>) – Variable to escape (string or array)</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">HTML escaped string(s)</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">mixed</p>
</td>
</tr>
</tbody>
</table>
<p>This function acts as an alias for PHP’s native <code class="docutils literal"><span class="pre">htmlspecialchars()</span></code>
function, with the advantage of being able to accept an array of strings.</p>
<p>It is useful in preventing Cross Site Scripting (XSS).</p>
</dd></dl>
<dl class="function">
<dt id="get_mimes">
<code class="descname">get_mimes</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#get_mimes" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Returns:</th><td class="field-body">An associative array of file types</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body">array</td>
</tr>
</tbody>
</table>
<p>This function returns a <em>reference</em> to the MIMEs array from
<em>application/config/mimes.php</em>.</p>
</dd></dl>
<dl class="function">
<dt id="is_https">
<code class="descname">is_https</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#is_https" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Returns:</th><td class="field-body">TRUE if currently using HTTP-over-SSL, FALSE if not</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body">bool</td>
</tr>
</tbody>
</table>
<p>Returns TRUE if a secure (HTTPS) connection is used and FALSE
in any other case (including non-HTTP requests).</p>
</dd></dl>
<dl class="function">
<dt id="is_cli">
<code class="descname">is_cli</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#is_cli" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Returns:</th><td class="field-body">TRUE if currently running under CLI, FALSE otherwise</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body">bool</td>
</tr>
</tbody>
</table>
<p>Returns TRUE if the application is run through the command line
and FALSE if not.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">This function checks both if the <code class="docutils literal"><span class="pre">PHP_SAPI</span></code> value is ‘cli’
or if the <code class="docutils literal"><span class="pre">STDIN</span></code> constant is defined.</p>
</div>
</dd></dl>
<dl class="function">
<dt id="function_usable">
<code class="descname">function_usable</code><span class="sig-paren">(</span><em>$function_name</em><span class="sig-paren">)</span><a class="headerlink" href="#function_usable" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$function_name</strong> (<em>string</em>) – Function name</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">TRUE if the function can be used, FALSE if not</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">bool</p>
</td>
</tr>
</tbody>
</table>
<p>Returns TRUE if a function exists and is usable, FALSE otherwise.</p>
<p>This function runs a <code class="docutils literal"><span class="pre">function_exists()</span></code> check and if the
<cite>Suhosin extension <http://www.hardened-php.net/suhosin/></cite> is loaded,
checks if it doesn’t disable the function being checked.</p>
<p>It is useful if you want to check for the availability of functions
such as <code class="docutils literal"><span class="pre">eval()</span></code> and <code class="docutils literal"><span class="pre">exec()</span></code>, which are dangerous and might be
disabled on servers with highly restrictive security policies.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">This function was introduced because Suhosin terminated
script execution, but this turned out to be a bug. A fix
has been available for some time (version 0.9.34), but is
unfortunately not released yet.</p>
</div>
</dd></dl>
</div>
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