PHP | preg_filter() Function

The preg_filter() function is an inbuilt function in PHP which is used to perform a regular expression search and replace the text.

Syntax:

preg_filter( $pattern, $replacement, $subject, $limit, $count )

Parameters: This function accepts five parameters as mention above and describe below.

• $pattern: This parameter contains an string element which is search for and it can be a string or array of string.
• $replacement: It is mandatory parameter which specifies the string or an array with strings to replace.
• $subject: The string or an array with strings to search and replace.
• $limit: This parameter specifies the maximum possible replacements for each pattern.
• $count: It is optional parameter which is used to fill with the number of replacements done.

Return Value: This function returns an array if the subject parameter is an array, or a string otherwise.

Below program illustrates the preg_filter() function in PHP:
Program 1:

<?php

// PHP program to illustrate
// preg_filter function
$string = 'November 01, 2018';
$pattern = '/(\w+) (\d+), (\d+)/i';
$replacement = '${1} 02, $3';

// print result
echo preg_filter($pattern, $replacement, $string);
?>

Output:

November 02, 2018

Program 2 :

<?php

// PHP program to illustrate preg_filter function
$subject = array('1', 'GFG', '2',
        'Geeks', '3', 'GCET', 'Contribute', '4');
$pattern = array('/\d/', '/[a-z]/', '/[1a]/');
$replace = array('X:$0', 'Y:$0', 'Z:$0');

echo "Returned Array by preg_filter";
print_r(preg_filter($pattern, $replace, $subject));
?>

Output:

Returned Array by preg_filterArray
(
    [0] => X:Z:1
    [2] => X:2
    [3] => GY:eY:eY:kY:s
    [4] => X:3
    [6] => CY:oY:nY:tY:rY:iY:bY:uY:tY:e
    [7] => X:4
)

Reference: http://php.net/manual/en/function.preg-filter.php