int preg_match(string pattern, string subject, array [matches]);
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 will contain the text that match the full pattern, $matches will have the text that matched the first captured parenthesized subpattern, and so on.
Returns true if a match for pattern was found in the subject string, or false if not match was found or an error occurred.
Example 1. Getting the page number out of a string
if (preg_match("/page\s+#(\d+)/i", "Go to page #9.", $parts)) print "Next page is $parts"; else print "Page not found.";