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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.6 $ -->
<!-- splitted from ./en/functions/strings.xml, last change in rev 1.37 -->
<refentry id="function.crc32">
<refnamediv>
<refname>crc32</refname>
<refpurpose>Calculates the crc32 polynomial of a string</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<methodsynopsis>
<type>int</type><methodname>crc32</methodname>
<methodparam><type>string</type><parameter>str</parameter></methodparam>
</methodsynopsis>
<para>
Generates the cyclic redundancy checksum polynomial of 32-bit
lengths of the <parameter>str</parameter>. This is usually used
to validate the integrity of data being transmitted.
</para>
<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
<function>sprintf</function> or <function>printf</function> to get
the string representation of the unsigned crc32 checksum.
</para>
<para>
This second example shows how to print a converted checksum with the
<function>printf</function> function:
<example>
<title>Displaying a crc32 checksum</title>
<programlisting role="php">
<![CDATA[
<?php
$checksum = crc32("The quick brown fox jumped over the lazy dog.");
printf("%u\n", $checksum);
?>
]]>
</programlisting>
</example>
</para>
<para>
See also <function>md5</function> and <function>sha1</function>.
</para>
</refsect1>
</refentry>
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