preg_filter

(PHP 5 >= 5.3.0, PHP 7)

Perform a regular expression search and replace

mixed preg_filter ( mixed $pattern, mixed $replacement, mixed $subject [, int $limit = -1 [, int &$count ]] )

preg_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.

Returns:

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.

Examples:

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
)