... PHP 4 >= 4.0.0) preg_grep -- Return array entries that match the pattern . array preg_grep ( string pattern, array input) . preg_grep() returns the array consisting of the elements of the input array that match the given pattern . Since PHP 4.0.4, the results returned by preg_grep() are indexed using the keys from the input array. ... Example 1. preg_grep() example . return all array elements // containing floating point numbers $fl_array = preg_grep ("/^(\d+)?\.\d+$/", $array); . ...