function.crc32.html
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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>Calculates the crc32 polynomial of a string</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.count-chars.html">count_chars</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.crypt.html">crypt</a></div> <div class="up"><a href="ref.strings.html">String Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.crc32" class="refentry"> <div class="refnamediv"> <h1 class="refname">crc32</h1> <p class="verinfo">(PHP 4 >= 4.0.1, PHP 5)</p><p class="refpurpose"><span class="refname">crc32</span> — <span class="dc-title">Calculates the crc32 polynomial of a string</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">int</span> <span class="methodname"><b><b>crc32</b></b></span> ( <span class="methodparam"><span class="type">string</span> <tt class="parameter">$str</tt></span> )</div> <p class="para rdfs-comment"> Generates the cyclic redundancy checksum polynomial of 32-bit lengths of the <i><tt class="parameter">str</tt></i>. This is usually used to validate the integrity of data being transmitted. </p> <p class="para"> Because PHP's integer type is signed, and many crc32 checksums will result in negative integers, you need to use the "%u" formatter of <a href="function.sprintf.html" class="function">sprintf()</a> or <a href="function.printf.html" class="function">printf()</a> to get the string representation of the unsigned crc32 checksum. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">str</tt></i></span> <dd> <p class="para"> The data. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns the crc32 checksum of <i><tt class="parameter">str</tt></i> as an integer. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 Displaying a crc32 checksum</b></p> <div class="example-contents"><p> This example shows how to print a converted checksum with the <a href="function.printf.html" class="function">printf()</a> function: </p></div> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$checksum </span><span style="color: #007700">= </span><span style="color: #0000BB">crc32</span><span style="color: #007700">(</span><span style="color: #DD0000">"The quick brown fox jumped over the lazy dog."</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"%u\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$checksum</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.md5.html" class="function" rel="rdfs-seeAlso">md5()</a></li> <li class="member"><a href="function.sha1.html" class="function" rel="rdfs-seeAlso">sha1()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.count-chars.html">count_chars</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.crypt.html">crypt</a></div> <div class="up"><a href="ref.strings.html">String Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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