preg_match Perform a regular expression match intpreg_match stringpattern stringsubject arraymatches intflags 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. flags can be the following flag: PREG_OFFSET_CAPTURE If this flag is set, for every occuring match the appendant string offset will also be returned. Note that this changes the return value in an array where every element is an array consisting of the matched string at offset 0 and it's string offset into subject at offset 1. This flag is available since PHP 4.3.0 . The flags parameter is available since PHP 4.3.0 . 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. Do not use preg_match if you only want to check if one string is contained in another string. Use strpos or strstr instead as they will be faster. ]]> ]]> ]]> This example will produce: See also preg_match_all, preg_replace, and preg_split.