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</div><hr /><div id="function.eval" class="refentry">
<div class="refnamediv">
<h1 class="refname">eval</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">eval</span> — <span class="dc-title">Evaluate a string as PHP code</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.eval-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <span class="methodname"><strong>eval</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$code</code></span>
)</div>
<p class="para rdfs-comment">
Evaluates the given <em><code class="parameter">code</code></em> as PHP.
</p>
<div class="caution"><strong class="caution">Caution</strong>
<p class="para">
The <span class="function"><strong>eval()</strong></span> language construct is <em class="emphasis">very dangerous</em>
because it allows execution of arbitrary PHP code. <em class="emphasis">Its use thus is
discouraged.</em> If you have carefully verified that there is no other option
than to use this construct, pay special attention <em class="emphasis">not to pass any user
provided data</em> into it without properly validating it beforehand.
</p>
</div>
</div>
<div class="refsect1 parameters" id="refsect1-function.eval-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">code</code></em></span>
<dd>
<p class="para">
Valid PHP code to be evaluated.
</p>
<p class="para">
The code mustn't be wrapped in opening and closing
<a href="language.basic-syntax.phpmode.html" class="link">PHP tags</a>, i.e.
<em>'echo "Hi!";'</em> must be passed instead of
<em>'<? echo "Hi!"; >'</em>. It is still possible to leave and
reenter PHP mode though using the appropriate PHP tags, e.g.
<em>'echo "In PHP mode!"; ?>In HTML mode!<? echo "Back in PHP mode!";'</em>.
</p>
<p class="para">
Apart from that the passed code must be valid PHP. This includes that all statements
must be properly terminated using a semicolon.
<em>'echo "Hi!"'</em> for example will cause a parse error, whereas
<em>'echo "Hi!";'</em> will work.
</p>
<p class="para">
A <em>return</em> statement will immediately terminate the
evaluation of the code.
</p>
<p class="para">
The code will be executed in the scope of the code calling <span class="function"><strong>eval()</strong></span>. Thus any
variables defined or changed in the <span class="function"><strong>eval()</strong></span> call will remain visible after
it terminates.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.eval-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
<span class="function"><strong>eval()</strong></span> returns <strong><code>NULL</code></strong> unless
<em>return</em> is called in the evaluated code, in which case
the value passed to <em>return</em> is returned. If there is a
parse error in the evaluated code, <span class="function"><strong>eval()</strong></span> returns
<strong><code>FALSE</code></strong> and execution of the following code continues normally. It is
not possible to catch a parse error in <span class="function"><strong>eval()</strong></span>
using <span class="function"><a href="function.set-error-handler.html" class="function">set_error_handler()</a></span>.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.eval-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-3774">
<p><strong>Example #1 <span class="function"><strong>eval()</strong></span> example - simple text merge</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$string </span><span style="color: #007700">= </span><span style="color: #DD0000">'cup'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$name </span><span style="color: #007700">= </span><span style="color: #DD0000">'coffee'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$str </span><span style="color: #007700">= </span><span style="color: #DD0000">'This is a $string with my $name in it.'</span><span style="color: #007700">;<br />echo </span><span style="color: #0000BB">$str</span><span style="color: #007700">. </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />eval(</span><span style="color: #DD0000">"\$str = \"</span><span style="color: #0000BB">$str</span><span style="color: #DD0000">\";"</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">$str</span><span style="color: #007700">. </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
This is a $string with my $name in it.
This is a cup with my coffee in it.
</pre></div>
</div>
</div>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.eval-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">Because this is a
language construct and not a function, it cannot be called using
<a href="functions.variable-functions.html" class="link">variable functions</a>.</span>
</p></blockquote>
<div class="tip"><strong class="tip">Tip</strong><p class="simpara">As with anything that outputs
its result directly to the browser, the <a href="book.outcontrol.html" class="link">output-control functions</a> can be used to capture
the output of this function, and save it in a
<span class="type"><a href="language.types.string.html" class="type string">string</a></span> (for example).</p></div>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
In case of a fatal error in the evaluated code, the whole script exits.
</p>
</p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-function.eval-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.call-user-func.html" class="function" rel="rdfs-seeAlso">call_user_func()</a> - Call the callback given by the first parameter</span></li>
</ul>
</p>
</div>
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