<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Finds whether a value is not a number</title> </head> <body><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.is-infinite.html">is_infinite</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.lcg-value.html">lcg_value</a></div> <div class="up"><a href="ref.math.html">Math Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div><hr /><div id="function.is-nan" class="refentry"> <div class="refnamediv"> <h1 class="refname">is_nan</h1> <p class="verinfo">(PHP 4 >= 4.2.0, PHP 5)</p><p class="refpurpose"><span class="refname">is_nan</span> — <span class="dc-title">Finds whether a value is not a number</span></p> </div> <div class="refsect1 description" id="refsect1-function.is-nan-description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">bool</span> <span class="methodname"><strong>is_nan</strong></span> ( <span class="methodparam"><span class="type">float</span> <code class="parameter">$val</code></span> )</div> <p class="para rdfs-comment"> Checks whether <em><code class="parameter">val</code></em> is 'not a number', like the result of <em>acos(1.01)</em>. </p> </div> <div class="refsect1 parameters" id="refsect1-function.is-nan-parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><em><code class="parameter">val</code></em></span> <dd> <p class="para"> The value to check </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues" id="refsect1-function.is-nan-returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns <strong><code>TRUE</code></strong> if <em><code class="parameter">val</code></em> is 'not a number', else <strong><code>FALSE</code></strong>. </p> </div> <div class="refsect1 examples" id="refsect1-function.is-nan-examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example" id="example-3462"> <p><strong>Example #1 <span class="function"><strong>is_nan()</strong></span> example</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Invalid calculation, will return a <br />// NaN value<br /></span><span style="color: #0000BB">$nan </span><span style="color: #007700">= </span><span style="color: #0000BB">acos</span><span style="color: #007700">(</span><span style="color: #0000BB">8</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$nan</span><span style="color: #007700">, </span><span style="color: #0000BB">is_nan</span><span style="color: #007700">(</span><span style="color: #0000BB">$nan</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> float(NAN) bool(true) </pre></div> </div> </div> </p> </div> <div class="refsect1 seealso" id="refsect1-function.is-nan-seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"> <span class="function"><a href="function.is-finite.html" class="function" rel="rdfs-seeAlso">is_finite()</a> - Finds whether a value is a legal finite number</span></li> <li class="member"> <span class="function"><a href="function.is-infinite.html" class="function" rel="rdfs-seeAlso">is_infinite()</a> - Finds whether a value is infinite</span></li> </ul> </p> </div> </div><hr /><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.is-infinite.html">is_infinite</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.lcg-value.html">lcg_value</a></div> <div class="up"><a href="ref.math.html">Math Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div></body></html>