preg_replace
PHP 3>= 3.0.9, PHP 4 >= 4.0.0)
preg_replace -- Perform a regular expression search and replace
Description
mixed preg_replace ( mixed pattern, mixed replacement, mixed subject [, int limit])
Searches subject for matches to pattern and replaces them with replacement. If limit is specified, then only limit matches will be replaced; if limit is omitted or is -1, then all matches are replaced.
Replacement may contain references of the form \n or (since PHP 4.0.4) $n, with the latter form being the preferred one. Every such reference will be replaced by the text captured by the n'th parenthesized pattern. n can be from 0 to 99, and \0 or $0 refers to the text matched by the whole pattern. Opening parentheses are counted from left to right (starting from 1) to obtain the number of the capturing subpattern.
If matches are found, the new subject will be returned, otherwise subject will be returned unchanged.
-----php.net
