XLIII. Regular expression functions

Regular expressions are used for complex string manipulation in PHP. The functions that support regular expressions are:

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.

Example 1. Regular expression examples

/* Returns true if "abc"
   is found anywhere in $string. */

/* Returns true if "abc"
   is found at the beginning of $string. */

/* Returns true if "abc"
   is found at the end of $string. */

/* Returns true if client browser
   is Netscape 2, 3 or MSIE 3. */

ereg("([[:alnum:]]+) ([[:alnum:]]+) ([[:alnum:]]+)",
/* 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 carriage return
   characters in $string. */

Table of Contents
ereg — regular expression match
ereg_replace — replace regular expression
eregi — case insensitive regular expression match
eregi_replace — replace regular expression case insensitive
split — split string into array by regular expression
sql_regcase — make regular expression for case insensitive match