preg_filter()

preg_filter() — Perform a regular expression search and replace.

Built-in function of PHP 8.5. The manual lists it as available in PHP 5 >= 5.3.0, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

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.

Signature

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

Parameters

This function takes no parameters.

Return value

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.

Example

A runnable snippet:

$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));

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

preg_quote(), preg_replace(), preg_replace_callback(), preg_grep(), preg_last_error()

All PHP 8.5 built-in functions

Reference card built from the PHP manual page preg_filter() (PHP documentation, CC BY 3.0). The page is generated from the manual, so the wording of the parameter and return value text follows php.net.