<?php
/* Prototype  : bool array_walk(array $input, string $funcname [, mixed $userdata])
 * Description: Apply a user function to every member of an array 
 * Source code: ext/standard/array.c
*/

/*
 * Testing array_walk() with an array having reference variables
*/

echo "*** Testing array_walk() : array with references ***\n";

$value1 = 10;
$value2 = -20;
$value3 = &$value1;
$value4 = 50;

// 'input' array containing references to above variables
$input = array(&$value1, &$value2, -35, &$value3, 0, &$value4);

// callback function
/* Prototype : callback(int $value, mixed $key)
 * Parameters : $value - values in given input array
 *              $key - keys in given input array
 * Description : function checks for the value whether positive or negative and displays according to that
 */
function callback($value, $key)
{
   // dump the arguments to check that they are passed
   // with proper type
   var_dump($key);  // key
   var_dump($value); // value
   echo "\n"; // new line to separate the output between each element
}

var_dump( array_walk($input, "callback"));

echo "Done"
?>
