PHP array_walk() Function
The array_walk() function is an inbuilt function in PHP. The array_walk() function walks through the entire array regardless of pointer position and applies a callback function or user-defined function to every element of the array. The array element’s keys and values are parameters in the callback function.
Syntax:
boolean array_walk($array, myFunction, $extraParam)
Parameters: This function accepts three parameters as described below:
- $array: This is a mandatory parameter and specifies the input array.
- myFunction: This parameter specifies the name of the user-defined function and is also mandatory. The user-defined function generally excepts two parameters of which the first parameter represent the array’s values and the second parameter represents the corresponding keys.
- $extraparam: This is an optional parameter. It specifies an extra parameter to the user-defined function in addition to the two parameters, array keys and values.
Return value: This function returns a boolean value. It returns TRUE on success or FALSE on failure.
Below programs illustrate the array_walk() function:
Program 1:
<?php // PHP program to illustrate array_walk() // function // user-defined callback function function myfunction($value, $key) { echo "The key $key has the value $value \n"; } // Input array $arr = array("a"=>"yellow", "b"=>"pink", "c"=>"purple"); // calling array_walk() with no extra parameter array_walk($arr, "myfunction"); ?> |
Output:
The key a has the value yellow The key b has the value pink The key c has the value purple
Program 2:
<?php // PHP program to illustrate array_walk() // function // user-defined callback function function myfunction($value, $key, $extraParam) { echo "The key $key $extraParam $value \n"; } // Input array $arr = array("a"=>"yellow", "b"=>"pink", "c"=>"purple"); // calling array_walk() with extra parameter array_walk($arr, "myfunction", "has the value"); ?> |
Output:
The key a has the value yellow The key b has the value pink The key c has the value purple
Program 3:
<?php // PHP program to illustrate array_walk() // function // user-defined callback function to // update array values - to update array // values, pass the first parameter by reference function myfunction(&$value, $key) { $value = $value + 10; } // Input array $arr = array("first"=>10, "second"=>20, "third"=>30); // calling array_walk() with no extra parameter array_walk($arr, "myfunction"); // printing array after updating values print_r($arr); ?> |
Output:
Array
(
[first] => 20
[second] => 30
[third] => 40
)
