PHP Tutorial - PHP array_walk() Function

Definition

The array_walk() function runs a user-defined function on each array element.

The array's keys and values are parameters in the function.

We can change the value in the user-defined function by specifying the first parameter as a reference: &$value.

Note

To walk an array inside an array, use the array_walk_recursive() function.

Syntax

PHP array_walk() Function has the following syntax.

array_walk(array,myfunction,parameter...)

Parameter

Parameter	Is Required	Description
array	Required.	Array to walk on
myfunction	Required.	The name of the user-defined function
parameter,...	Optional.	A parameter to the user-defined function. You can assign one parameter to the function, or as many as you like

Example 1

Map an array with user defined function


<?php
    function myfunction($value,$key){
        echo "The key $key has the value $value<br>";
    }
    $a=array("a"=>"A","b"=>"B","c"=>"java2s.com");
    array_walk($a,"myfunction");
?>

The code above generates the following result.

Example 2

With a parameter:


<?php
    function myfunction($value,$key,$p){
       echo "$key $p $value ==";
    }
    $a=array("a"=>"A","b"=>"B","c"=>"java2s.com");
    array_walk($a,"myfunction","has the value");
?>

The code above generates the following result.

Example 3

Change an array element's value. (using the &$value)


<?php
    function myfunction(&$value,$key){
       $value=" added";
    }
    $a=array("a"=>"A","b"=>"B","c"=>"java2s.com");
    array_walk($a,"myfunction");
    print_r($a);
?>

The code above generates the following result.