preg_filter

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

preg_filter — Perform a regular expression search and replace

Description

preg_filter(
    string|array $pattern,
    string|array $replacement,
    string|array $subject,
    int $limit = -1,
    int &$count = null
): string|array|null

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.

Parameters

Parameters are described in the documentation for preg_replace().

Return Values

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.

Errors/Exceptions

If the regex pattern passed does not compile to a valid regex, an E_WARNING is emitted.

Examples

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
)

See Also