preg_replace_callback

Name:preg_replace_callback

Category:Regular processing PCRE

Programming Language:php

One-line Description:Given the expression and callback, return a string where all matches of the expression are replaced with the substring returned by the callback function.

Definition and usage

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

Example

Calculate the number of letters for all words in a sentence:

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

$input = "Welcome to W3School.com.cn!" ;
$pattern = '/[a-z0-9\.]+/i' ;
$result = preg_replace_callback ( $pattern , 'countLetters' , $input ) ;
echo $result ;
?>

Try it yourself

grammar

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

parameter	describe
pattern	Required. A regular expression or array of regular expressions indicating what to search for.
replacements	Required. A callback function that returns a replacement. The callback function has a parameter that contains an array of matches. The first element of the array contains matches to the entire expression, while the rest contain matches to each group in the expression.
input	Required. A string or array of strings that are replaced on it.
limit	Optional. The default is -1, indicating no limit. Sets the limit on the number of replacements that can be made in each string.
count	Optional. After the function is executed, this variable will contain a number indicating how many replacements have been made.