PHP preg_filter() Function

PHP 正则表达式(PCRE)PHP Regular Expressions (PCRE)

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

Syntax

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

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

Parameter description:

  • $pattern: The pattern to search for. It can be a string or an array of strings.
  • $replacement: The string or array of strings used for replacement.
  • $subject: The string or array of strings to be searched and replaced.
  • $limit: Optional. The maximum number of replacements for each 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/', '/[a-z]/', '/[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 返回值：
Array
(
    [0] => A:C:1
    [1] => B:C:a
    [2] => A:2
    [3] => B:b
    [4] => A:3
    [7] => A:4
)
preg_replace 返回值：
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 matched results and ignores unmatched ones directly, while preg_replace also returns the unmatched elements 'A' and 'B' together.

PHP 正则表达式(PCRE)PHP Regular Expressions (PCRE)

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