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<h1 class="title">Introduction</h1>
<div class="tip"><strong class="tip">Tip</strong>
<p class="para">
PHP also supports regular expressions using a Perl-compatible syntax
using the <a href="book.pcre.html" class="link">PCRE functions</a>. Those functions
support non-greedy matching, assertions, conditional subpatterns, and a
number of other features not supported by the POSIX-extended regular
expression syntax.
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<div class="warning"><strong class="warning">Warning</strong>
<p class="para">
These regular expression functions are not binary-safe. The <a href="book.pcre.html" class="link">PCRE functions</a> are.
</p>
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<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
As of PHP 5.3.0 this extension is deprecated, calling any function
provided by this extension will issue an <strong><code>E_DEPRECATED</code></strong>
notice.
</p>
</p></blockquote>
<p class="para">
Regular expressions are used for complex string manipulation.
PHP uses the POSIX extended regular expressions as defined by POSIX
1003.2. For a full description of POSIX regular expressions see the <a href="http://www.tin.org/bin/man.cgi?section=7&topic=regex" class="link external">» regex
man pages</a> included in the regex directory in the PHP distribution. It's
in manpage format, so you'll want to do something along the lines of
<strong class="command">man /usr/local/src/regex/regex.7</strong> in order to read it.
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