mirror of
https://github.com/sigmasternchen/php-doc-en
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22e850b66c
Based on a patch contributed by Máté Kocsis <kocsismate@woohoolabs.com>. git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@351490 c90b9560-bf6c-de11-be94-00142212c4b1
277 lines
8.2 KiB
XML
277 lines
8.2 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<refentry xml:id="function.preg-replace-callback" xmlns="http://docbook.org/ns/docbook">
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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 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type class="union"><type>string</type><type>array</type><type>null</type></type><methodname>preg_replace_callback</methodname>
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<methodparam><type class="union"><type>string</type><type>array</type></type><parameter>pattern</parameter></methodparam>
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<methodparam><type>callable</type><parameter>callback</parameter></methodparam>
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<methodparam><type class="union"><type>string</type><type>array</type></type><parameter>subject</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>limit</parameter><initializer>-1</initializer></methodparam>
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<methodparam choice="opt"><type>int</type><parameter role="reference">count</parameter><initializer>&null;</initializer></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>flags</parameter><initializer>0</initializer></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>.
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</para>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<para>
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<variablelist>
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<varlistentry>
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<term><parameter>pattern</parameter></term>
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<listitem>
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<para>
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The pattern to search for. It can be either a string or an array with
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strings.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>callback</parameter></term>
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<listitem>
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<para>
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A callback that will be called and passed an array of matched elements
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in the <parameter>subject</parameter> string. The callback should
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return the replacement string. This is the callback signature:
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</para>
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<para>
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<methodsynopsis>
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<type>string</type><methodname><replaceable>handler</replaceable></methodname>
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<methodparam><type>array</type><parameter>matches</parameter></methodparam>
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</methodsynopsis>
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</para>
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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 an
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<link linkend="functions.anonymous">anonymous function</link> to
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declare the 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 function's name
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not used anywhere else.
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</para>
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<para>
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<example>
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<title><function>preg_replace_callback</function> and
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anonymous 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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$line = preg_replace_callback(
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'|<p>\s*\w|',
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function ($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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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>subject</parameter></term>
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<listitem>
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<para>
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The string or an array with strings to search and replace.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>limit</parameter></term>
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<listitem>
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<para>
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The maximum possible replacements for each pattern in each
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<parameter>subject</parameter> string. Defaults to
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<literal>-1</literal> (no limit).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>count</parameter></term>
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<listitem>
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<para>
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If specified, this variable will be filled with the number of
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replacements done.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>flags</parameter></term>
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<listitem>
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<para>
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<parameter>flags</parameter> can be a combination of the
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<constant>PREG_OFFSET_CAPTURE</constant> and
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<constant>PREG_UNMATCHED_AS_NULL</constant> flags, which influence the
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format of the matches array.
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See the description in <function>preg_match</function> for more details.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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<function>preg_replace_callback</function> returns an array if the
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<parameter>subject</parameter> parameter is an array, or a string
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otherwise. On errors the return value is &null;
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</para>
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<para>
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If matches are found, the new subject will be returned, otherwise
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<parameter>subject</parameter> will be returned unchanged.
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</para>
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</refsect1>
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<refsect1 role="changelog">
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&reftitle.changelog;
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<para>
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<informaltable>
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<tgroup cols="2">
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<thead>
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<row>
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<entry>&Version;</entry>
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<entry>&Description;</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>7.4.0</entry>
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<entry>
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The <parameter>flags</parameter> parameter was added.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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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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$text);
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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April fools day is 04/01/2003
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Last christmas was 12/24/2002
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]]>
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</screen>
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</example>
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</para>
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<para>
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<example>
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<title><function>preg_replace_callback</function> using recursive structure
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to handle encapsulated BB code</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$input = "plain [indent] deep [indent] deeper [/indent] deep [/indent] plain";
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function parseTagsRecursive($input)
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{
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$regex = '#\[indent]((?:[^[]|\[(?!/?indent])|(?R))+)\[/indent]#';
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if (is_array($input)) {
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$input = '<div style="margin-left: 10px">'.$input[1].'</div>';
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}
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return preg_replace_callback($regex, 'parseTagsRecursive', $input);
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}
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$output = parseTagsRecursive($input);
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echo $output;
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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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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><link linkend="pcre.pattern">PCRE Patterns</link></member>
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<member><function>preg_replace_callback_array</function></member>
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<member><function>preg_quote</function></member>
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<member><function>preg_replace</function></member>
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<member><function>preg_last_error</function></member>
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<member><link linkend="functions.anonymous">Anonymous functions</link></member>
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</simplelist>
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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:"~/.phpdoc/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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