mirror of
https://github.com/sigmasternchen/php-doc-en
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e5dacc095d
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@181961 c90b9560-bf6c-de11-be94-00142212c4b1
118 lines
3.8 KiB
XML
118 lines
3.8 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.10 $ -->
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<!-- splitted from ./en/functions/pcre.xml, last change in rev 1.47 -->
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<refentry id="function.preg-replace-callback">
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<refnamediv>
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<refname>preg_replace_callback</refname>
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<refpurpose>Perform a regular expression search and replace using a callback</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>mixed</type><methodname>preg_replace_callback</methodname>
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<methodparam><type>mixed</type><parameter>pattern</parameter></methodparam>
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<methodparam><type>callback</type><parameter>callback</parameter></methodparam>
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<methodparam><type>mixed</type><parameter>subject</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>limit</parameter></methodparam>
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</methodsynopsis>
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<para>
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The behavior of this function is almost identical to
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<function>preg_replace</function>, except for the fact that instead of
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<parameter>replacement</parameter> parameter, one should specify a
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<parameter>callback</parameter> that will be called and passed an array of
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matched elements in the subject string. The callback should return the
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replacement string.
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</para>
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<example>
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<title><function>preg_replace_callback</function> example</title>
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<programlisting role='php'>
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<![CDATA[
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<?php
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// this text was used in 2002
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// we want to get this up to date for 2003
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$text = "April fools day is 04/01/2002\n";
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$text.= "Last christmas was 12/24/2001\n";
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// the callback function
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function next_year($matches)
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{
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// as usual: $matches[0] is the complete match
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// $matches[1] the match for the first subpattern
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// enclosed in '(...)' and so on
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return $matches[1].($matches[2]+1);
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}
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echo preg_replace_callback(
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"|(\d{2}/\d{2}/)(\d{4})|",
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"next_year",
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$text);
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// result is:
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// April fools day is 04/01/2003
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// Last christmas was 12/24/2002
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?>
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]]>
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</programlisting>
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</example>
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<para>
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You'll often need the <parameter>callback</parameter> function
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for a <function>preg_replace_callback</function> in just one place.
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In this case you can use <function>create_function</function> to
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declare an anonymous function as callback within the call to
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<function>preg_replace_callback</function>. By doing it this way
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you have all information for the call in one place and do not
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clutter the function namespace with a callback functions name
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not used anywhere else.
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</para>
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<example>
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<title><function>preg_replace_callback</function> and <function>create_function</function></title>
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<programlisting role='php'>
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<![CDATA[
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<?php
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/* a unix-style command line filter to convert uppercase
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* letters at the beginning of paragraphs to lowercase */
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$fp = fopen("php://stdin", "r") or die("can't read stdin");
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while (!feof($fp)) {
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$line = fgets($fp);
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$line = preg_replace_callback(
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'|<p>\s*\w|',
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create_function(
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// single quotes are essential here,
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// or alternative escape all $ as \$
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'$matches',
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'return strtolower($matches[0]);'
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),
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$line
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);
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echo $line;
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}
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fclose($fp);
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?>
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]]>
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</programlisting>
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</example>
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<para>
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See also <function>preg_replace</function>,
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<function>create_function</function>,
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&listendand; &seealso.callback;.
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"../../../../manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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