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(PHP 3 >= 3.0.3, PHP 4, PHP 5)

array_walk --  Apply a user function to every member of an array

Description

bool array_walk ( array &array, callback funcname [, mixed userdata] )

Returns TRUE on success or FALSE on failure.

Applies the user-defined function funcname to each element of the array array. Typically, funcname takes on two parameters. The array parameter's value being the first, and the key/index second. If the optional userdata parameter is supplied, it will be passed as the third parameter to the callback funcname .

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() .

array_walk() is not affected by the internal array pointer of array . array_walk() will walk through the entire array regardless of pointer position. To reset the pointer, use reset() . In PHP 3, array_walk() resets the pointer.

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.

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

Related Function(s)

error_reporting()

reset()

array_walk_recursive()

create_function()

list()

each()

call_user_func_array()

array_map()