(PHP 5 >= 5.3.0, PHP 7, PHP 8)
preg_filter — Perform a regular expression search and replace
$pattern,$replacement,$subject,$limit = -1,&$count = nullpreg_filter() is identical to preg_replace() except it only returns the (possibly transformed) subjects where there was a match. For details about how this function works, read the preg_replace() documentation.
Parameters are described in the documentation for preg_replace().
Returns an array if the subject parameter is an array, or a string otherwise.
If no matches are found or an error occurred, an empty array is returned when subject is an array or null otherwise.
If the regex pattern passed does not compile to a valid regex, an E_WARNING is emitted.
Example #1 Example comparing preg_filter() with preg_replace()
<?php
$subject = array('1', 'a', '2', 'b', '3', 'A', 'B', '4');
$pattern = array('/\d/', '/[a-z]/', '/[1a]/');
$replace = array('A:$0', 'B:$0', 'C:$0');
echo "preg_filter returns\n";
print_r(preg_filter($pattern, $replace, $subject));
echo "preg_replace returns\n";
print_r(preg_replace($pattern, $replace, $subject));
?>The above example will output:
preg_filter returns Array ( [0] => A:C:1 [1] => B:C:a [2] => A:2 [3] => B:b [4] => A:3 [7] => A:4 ) preg_replace returns Array ( [0] => A:C:1 [1] => B:C:a [2] => A:2 [3] => B:b [4] => A:3 [5] => A [6] => B [7] => A:4 )