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 <reference id="ref.regex">
  <title>Regular Expression Functions (POSIX Extended)</title>
  <titleabbrev>Regexps</titleabbrev>

  <partintro>
   <note>
    <para>
     PHP also supports regular expressions using a Perl-compatible syntax
     using the <link linkend="ref.pcre">PCRE functions</link>. Those functions
     support non-greedy matching, assertions, conditional subpatterns, and a
     number of other features not supported by the POSIX-extended regular
     expression syntax.
    </para>
   </note>
   <warning>
    <para>
     These regular expression functions are not binary-safe. The <link
      linkend="ref.pcre">PCRE functions</link> are.
    </para>
   </warning>
   <para>
    Regular expressions are used for complex string manipulation in
    PHP. The functions that support regular expressions are:
    <itemizedlist>
     <listitem>
      <simpara><function>ereg</function></simpara>
     </listitem>
     <listitem>
      <simpara><function>ereg_replace</function></simpara>
     </listitem>
     <listitem>
      <simpara><function>eregi</function></simpara>
     </listitem>
     <listitem>
      <simpara><function>eregi_replace</function></simpara>
     </listitem>
     <listitem>
      <simpara><function>split</function></simpara>
     </listitem>
     <listitem>
      <simpara><function>spliti</function></simpara>
     </listitem>
    </itemizedlist>
    These functions all take a regular expression string as their
    first argument.  PHP uses the POSIX extended regular expressions
    as defined by POSIX 1003.2.  For a full description of POSIX
    regular expressions see the regex man pages 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 <command>man
    /usr/local/src/regex/regex.7</command> in order to read it.
   </para>
   <para>
    <example>
     <title>Regular Expression Examples</title>
     <programlisting role="php">
<![CDATA[
ereg ("abc", $string);            
/* Returns true if"abc"
   is found anywhere in $string. */

ereg ("^abc", $string);
/* Returns true if "abc";
   is found at the beginning of $string. */

ereg ("abc$", $string);
/* Returns true if "abc"
   is found at the end of $string. */

eregi ("(ozilla.[23]|MSIE.3)", $HTTP_USER_AGENT);  
/* Returns true if client browser
   is Netscape 2, 3 or MSIE 3. */

ereg ("([[:alnum:]]+) ([[:alnum:]]+) ([[:alnum:]]+)", $string,$regs); 
/* Places three space separated words
   into $regs[1], $regs[2] and $regs[3]. */

$string = ereg_replace ("^", "<br />", $string); 
/* Put a <br /> tag at the beginning of $string. */
 
$string = ereg_replace ("$", "<br />", $string); 
/* Put a <br />; tag at the end of $string. */

$string = ereg_replace ("\n", "", $string);
/* Get rid of any newline
   characters in $string. */
]]>
     </programlisting>
    </example>
   </para>
  </partintro>





  


&reference.regex.functions;

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