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array_walk
(PHP 4, PHP 5)
array_walk — Apply a user function to every member of an array
Description
Applies the user-defined function funcname to each element of the array array.
array_walk() is not affected by the internal array pointer of array . array_walk() will walk through the entire array regardless of pointer position.
Parameters
- array
-
The input array.
- funcname
-
Typically, funcname takes on two parameters. The array parameter's value being the first, and the key/index second.
Note: If funcname needs to be working with the actual values of the array, specify the first parameter of funcname as a reference. Then, any changes made to those elements will be made in the original array itself.
Users may not change the array itself from the callback function. e.g. Add/delete elements, unset elements, etc. If the array that array_walk() is applied to is changed, the behavior of this function is undefined, and unpredictable.
- userdata
-
If the optional userdata parameter is supplied, it will be passed as the third parameter to the callback funcname .
Return Values
Returns TRUE on success or FALSE on failure.
Errors/Exceptions
If function funcname requires more parameters than given to it, an error of level E_WARNING will be generated each time array_walk() calls funcname . These warnings may be suppressed by prepending the PHP error operator @ to the array_walk() call, or by using error_reporting().
ChangeLog
| Version | Description |
|---|---|
| 4.0.0 | Passing the key and userdata to funcname was added. |
Examples
Example #1 array_walk() example
<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
function test_alter(&$item1, $key, $prefix)
{
$item1 = "$prefix: $item1";
}
function test_print($item2, $key)
{
echo "$key. $item2<br />\n";
}
echo "Before ...:\n";
array_walk($fruits, 'test_print');
array_walk($fruits, 'test_alter', 'fruit');
echo "... and after:\n";
array_walk($fruits, 'test_print');
?>
The above example will output:
Before ...: d. lemon a. orange b. banana c. apple ... and after: d. fruit: lemon a. fruit: orange b. fruit: banana c. fruit: apple
See Also
- array_walk_recursive()
- create_function()
- list()
- each()
- call_user_func_array()
- array_map()
- information about the callback type
- foreach
