Tutorials References Exercises Videos Menu
Create Website Get Certified Upgrade

PHP Tutorial

PHP HOME PHP Intro PHP Install PHP Syntax PHP Comments PHP Variables PHP Echo / Print PHP Data Types PHP Strings PHP Numbers PHP Math PHP Constants PHP Operators PHP If...Else...Elseif PHP Switch PHP Loops PHP Functions PHP Arrays PHP Superglobals PHP RegEx

PHP Forms

PHP Form Handling PHP Form Validation PHP Form Required PHP Form URL/E-mail PHP Form Complete

PHP Advanced

PHP Date and Time PHP Include PHP File Handling PHP File Open/Read PHP File Create/Write PHP File Upload PHP Cookies PHP Sessions PHP Filters PHP Filters Advanced PHP Callback Functions PHP JSON PHP Exceptions

PHP OOP

PHP What is OOP PHP Classes/Objects PHP Constructor PHP Destructor PHP Access Modifiers PHP Inheritance PHP Constants PHP Abstract Classes PHP Interfaces PHP Traits PHP Static Methods PHP Static Properties PHP Namespaces PHP Iterables

MySQL Database

MySQL Database MySQL Connect MySQL Create DB MySQL Create Table MySQL Insert Data MySQL Get Last ID MySQL Insert Multiple MySQL Prepared MySQL Select Data MySQL Where MySQL Order By MySQL Delete Data MySQL Update Data MySQL Limit Data

PHP XML

PHP XML Parsers PHP SimpleXML Parser PHP SimpleXML - Get PHP XML Expat PHP XML DOM

PHP - AJAX

AJAX Intro AJAX PHP AJAX Database AJAX XML AJAX Live Search AJAX Poll

PHP Examples

PHP Examples PHP Compiler PHP Quiz PHP Exercises PHP Certificate

PHP Reference

PHP Overview PHP Array PHP Calendar PHP Date PHP Directory PHP Error PHP Exception PHP Filesystem PHP Filter PHP FTP PHP JSON PHP Keywords PHP Libxml PHP Mail PHP Math PHP Misc PHP MySQLi PHP Network PHP Output Control PHP RegEx PHP SimpleXML PHP Stream PHP String PHP Variable Handling PHP XML Parser PHP Zip PHP Timezones

PHP preg_replace_callback() Function

❮ PHP RegExp Reference

Example

Count letters in all of the words in a sentence:

<?php
function countLetters($matches) {
  return $matches[0] . '(' . strlen($matches[0]) . ')';
}

$input = "Welcome to W3Schools.com!";
$pattern = '/[a-z0-9\.]+/i';
$result = preg_replace_callback($pattern, 'countLetters', $input);
echo $result;
?>
Try it Yourself »

Definition and Usage

The preg_replace_callback() function, given an expression and a callback, returns a string where all matches of the expression are replaced with the substring returned by the callback function.


Syntax

preg_replace_callback(pattern, callback, input, limit, count)

Parameter Values

Parameter Description
pattern Required. A regular expression or array of regular expressions indicating what to search for
replacements Required. A callback function which returns the replacement.

The callback function has one parameter containing an array of matches. The first element in the array contains the match for the whole expression while the remaining elements have matches for each of the groups in the expression.
input Required. The string or array of strings in which replacements are being performed
limit Optional. Defaults to -1, meaning unlimited. Sets a limit to how many replacements can be done in each string
count Optional. After the function has executed, this variable will contain a number indicating how many replacements were performed

Technical Details

Return Value: Returns a string or an array of strings resulting from applying the replacements to the input string or strings.
PHP Version: 4.0.5+
Changelog: PHP 5.1.0 - The count parameter was added

❮ PHP RegExp Reference