preg_match

Description

int preg_match ( string pattern, string subject [, array matches [, int flags]])

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:

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.

Example 1. Find the string of text "php" <?php // The "i" after the pattern delimiter indicates a case-insensitive search if (preg_match ("/php/i", "PHP is the web scripting language of choice.")) { print "A match was found."; } else { print "A match was not found."; } ?>

Example 2. Find the word "web" <?php /* The \b in the pattern indicates a word boundary, so only the distinct * word "web" is matched, and not a word partial like "webbing" or "cobweb" */ if (preg_match ("/\bweb\b/i", "PHP is the web scripting language of choice.")) { print "A match was found."; } else { print "A match was not found."; } if (preg_match ("/\bweb\b/i", "PHP is the website scripting language of choice.")) { print "A match was found."; } else { print "A match was not found."; } ?>

Example 3. Getting the domain name out of a URL <?php // get host name from URL preg_match("/^(http:\/\/)?([^\/]+)/i", "http://www.php.net/index.html", $matches); $host = $matches[2]; // get last two segments of host name preg_match("/[^\.\/]+\.[^\.\/]+$/", $host, $matches); echo "domain name is: {$matches[0]}\n"; ?> This example will produce: domain name is: php.net

See also preg_match_all(), preg_replace(), and preg_split().