preg_match Perform a regular expression match intpreg_match stringpattern stringsubject arraymatches Searches subject for a match to the regular expression given in pattern. If matches is provided, then it is filled with the results of search. $matches[0] will contain the text that matched the full pattern, $matches[1] will have the text that matched the first captured parenthesized subpattern, and so on. preg_match returns the number of times pattern matches. That will be either 0 times (no match) or 1 time because preg_match will stop searching after the first match. preg_match_all on the contrary will continue until it reaches the end of subject. preg_match returns &false; if an error occured. This example will produce: See also preg_match_all, preg_replace, and preg_split.