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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Get value of pi</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.octdec.html">octdec</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.pow.html">pow</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.pi" class="refentry"> <div class="refnamediv"> <h1 class="refname">pi</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">pi</span> — <span class="dc-title">Get value of pi</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">float</span> <span class="methodname"><b><b>pi</b></b></span> ( <span class="methodparam">void</span> )</div> <p class="simpara"> Returns an approximation of pi. The returned <a href="language.types.float.html" class="type float">float</a> has a precision based on the <a href="ini.core.html#ini.precision" class="link">precision</a> directive in <var class="filename">php.ini</var>, which defaults to <i>14</i>. Also, you can use the <b><tt>M_PI</tt></b> constant which yields identical results to <b>pi()</b>. </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> The value of pi as float. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 <b>pi()</b> example</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">pi</span><span style="color: #007700">(); </span><span style="color: #FF8000">// 3.1415926535898<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">M_PI</span><span style="color: #007700">; </span><span style="color: #FF8000">// 3.1415926535898<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.octdec.html">octdec</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.pow.html">pow</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>?? 快捷鍵說明
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