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.
Only the values of the array may potentially be changed; its structure cannot be altered, i.e., the programmer cannot add, unset or reorder elements. If the callback does not respect this requirement, 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().
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() - Apply a user function recursively to every member of an array
- iterator_apply() - Call a function for every element in an iterator
- create_function() - Create an anonymous (lambda-style) function
- list() - Assign variables as if they were an array
- each() - Return the current key and value pair from an array and advance the array cursor
- call_user_func_array() - Call a user function given with an array of parameters
- array_map() - Applies the callback to the elements of the given arrays
- information about the callback type
- foreach