<?php
$str = "Visit W3Schools";
$pattern = "/w3schools/i";
echo preg_match($pattern, $str); // Outputs 1
?><?php
preg_filter() Returns a string or an array with pattern matches replaced, but only if matches were found
preg_grep() Returns an array consisting only of elements from the input array which matched the pattern
preg_last_error() Returns an error code indicating the reason that the most recent regular expression call failed
preg_match() Finds the first match of a pattern in a string
preg_match_all() Finds all matches of a pattern in a string
preg_replace() Returns a string where matches of a pattern (or an array of patterns) are replaced with a substring (or an array of substrings) in a given string
preg_replace_callback() Given an expression and a callback, returns a string where all matches of the expression are replaced with the substring returned by the callback
preg_replace_callback_array() Given an array associating expressions with callbacks, returns a string where all matches of each expression are replaced with the substring returned by the callback
preg_split() Breaks a string into an array using matches of a regular expression as separators
preg_quote() Escapes characters that have a special meaning in regular expressions by putting a backslash in front of them
?>