# PHP array_walk() Function

PHP Array Reference

## Example

Run each array element in a user-defined function:

<?php
function myfunction($value,$key)
{
echo "The key $key has the value $value<br>";
}
$a=array("a"=>"red","b"=>"green","c"=>"blue");
array_walk($a,"myfunction");
?>
Run example »

## Definition and Usage

The array_walk() function runs each array element in a user-defined function. The array's keys and values are parameters in the function.

Note: You can change an array element's value in the user-defined function by specifying the first parameter as a reference: &$value (See Example 2).

Tip: To work with deeper arrays (an array inside an array), use the array_walk_recursive() function.

## Syntax

array_walk(array,myfunction,parameter...)

Parameter | Description
--- | ---
array | Required. Specifying an array
myfunction | Required. The name of the user-defined function
parameter,... | Optional. Specifies a parameter to the user-defined function. You can assign one parameter to the function, or as many as you like

## Technical Details

Return Value: | Returns TRUE on success or FALSE on failure
PHP Version: | 4+

## More Examples

## Example 1

With a parameter:

<?php
function myfunction($value,$key,$p)
{
echo "$key $p $value<br>";
}
$a=array("a"=>"red","b"=>"green","c"=>"blue");
array_walk($a,"myfunction","has the value");
?>
Run example »

## Example 2

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

<?php
function myfunction(&$value,$key)
{
$value="yellow";
}
$a=array("a"=>"red","b"=>"green","c"=>"blue");
array_walk($a,"myfunction");
print_r($a);
?>
Run example »

PHP Array Reference

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