The PHP Array function array

Definitions and usage

The Array_walk () function applies a callback function to each element in the array. Returns TRUE if successful, otherwise returns FALSE.

Typically, a function accepts two parameters. the value of the array parameter is the first, and the key name is the second. If an optional parameter userdata is provided, it is passed as the third argument to the callback function.

If a function function requires more arguments than is given, a e_warning error is generated each time Array_walk () invokes the function. These warnings can be suppressed by adding PHP's error operator @ before the Array_walk () call, or by using error_reporting ().

Grammar

Array_walk (Array,function,userdata ...)

Parameters	Description
Array	Necessary. The specified array.
function	Necessary. The name of the user-defined function.
UserData	Optional. The value entered by the user as a parameter to the callback function.

Tips and comments

Tip: You can set one or more parameters for a function.

Note: If the callback function needs to act directly on the value in the array, you can specify the first argument of the callback function as the reference:& $value. (see example 3)

Note: Passing the key name and UserData to the function is a new addition to PHP 4.0.

Example 1

<?php
function MyFunction ($value, $key) {
	echo "The key $key has the value $value <br/>";
}

$a = Array ("A" => "Cat", "B" => "Dog", "C" => "Horse");
Array_walk ($a, "myfunction");

Output:

The key A has the value Cat
The key B has the value Dog
The key C has the value horse

Example 2

With one parameter:

<?php
function MyFunction ($value, $key, $p) {
	echo "$key $p $value <br/>";
}

$a = Array ("A" => "Cat", "B" => "Dog", "C" => "Horse");
Array_walk ($a, "myfunction", "has the value");
? >

Output:

A has the value Cat
B has the value Dog
C has the value horse

Example 3

Change the value of an array element (Note & $value): (This situation is more!) ）

<?php
function MyFunction (& $value, $key) {
	$value = "Bird";
}

$a = Array ("A" => "Cat", "B" => "Dog", "C" => "Horse");
Array_walk ($a, "myfunction");
Print_r ($a);

Output:

Array ([a] => Bird [b] => Bird [c] => Bird)

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