PHP preg_filter() function

Author：Eve Cole Update Time：2024-12-28 15:00:02

The preg_filter function is used to perform a regular expression search and replace.

grammar

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

preg_filter() is equivalent to preg_replace(), but it only returns results that match the target.

Parameter description:

$pattern: The pattern to search for. Can be a string or an array of strings.

$replacement: String or array of strings used for replacement.

$subject: The string or array of strings to search and replace.

$limit: Optional, the maximum number of substitutions per pattern on each subject. The default is -1 (unlimited).

$count: Optional, the number of replacements completed.

Example

Example comparing preg_filter() and preg_replace()

<?php $subject = array ( ' 1 ' , ' a ' , ' 2 ' , ' b ' , ' 3 ' , ' A ' , ' B ' , ' 4 ' ) ; $pattern = array ( ' /d/ ' , ' /[az]/ ' , ' /[1a]/ ' ) ; $replace = array ( ' A:$0 ' , ' B:$0 ' , ' C:$0 ' ) ; echo " preg_filter return value: n " ; print_r ( preg_filter ( $pattern , $replace , $subject ) ) ; echo " preg_replace return value: n " ; print_r ( preg_replace ( $pattern , $replace , $subject ) ) ; ?>

The execution result is as follows:

 preg_filter return value: Array( [0] => A:C:1 [1] => B:C:a [2] => A:2 [3] => B:b [4] => A:3 [7] => A:4)preg_replace return value: 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)

It can be seen that preg_filter only returns the matching results, and the unmatched ones are ignored directly, while preg_replace also returns the unmatched results 'A' and 'B' elements together.