PHP Array_walk () function

Definition and usage

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

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

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

Grammar

Array_walk (Array,function,userdata ...)

Parameter description

Array	Necessary. Specifies the array.
function	Necessary. The name of the user-defined function.
UserData	Optional. The value entered by the user, which can be used as a parameter to the callback function.

Hints and Notes

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

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

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

Example 1

 
  ";} $a =array ("a" and "Cat", "b" = "Dog", "C" and "Horse"); Array_walk ($a, "myfunction"); >

Output:

The key A has the value Catthe key B have the value Dogthe key C has the value Horse

Example 2

With one parameter:

 
  ";} $a =array ("a" and "Cat", "b" = "Dog", "c" = "Horse"), Array_walk ($a, "myfunction", "has the value");? >

Output:

A has the value CATB have the value DOGC has the value Horse

Example 3

Change the value of an array element (Note & $value):

 
  "Cat", "b" = "Dog", "C" and "Horse"); Array_walk ($a, "myfunction");p Rint_r ($a); >

Output:

Array ([A] = Bird [b] = Bird [c] = Bird)

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