PHP | Ds\Map apply() Function

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The Ds\Map::apply() function of the Map class in PHP is used to apply a specific operation to all of the elements present in the map. It accepts a callback function and updates all of the elements present in the Map according to the given callback function.

Syntax:

void public Ds\Map::apply ( callable $callback )

Note: The callback function should return the updated value for specific key-value pair.

Parameters: It accepts a callback function as a parameter and updates all of the elements according to that function.

Return value: This function does not returns any value.

Below programs illustrate the Ds\Map::apply() function in PHP:

Program 1:

<?php 
// PHP program to illustrate the apply() 
// function of Ds\map 
  
// Creating a Map 
$map = new \Ds\Map(["1" => "Geeks",  
            "2" => "for", "3" => "Geeks"]); 
  
// Converting all elements to uppercase  
// using callback function 
$map->apply(function($key, $value){  
                return strtoupper($value); 
            }); 
  
print_r($map); 
  
?> 

Output:

Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => 1
            [value] => GEEKS
        )

    [1] => Ds\Pair Object
        (
            [key] => 2
            [value] => FOR
        )

    [2] => Ds\Pair Object
        (
            [key] => 3
            [value] => GEEKS
        )

)

Program 2:

<?php 
// PHP program to illustrate the apply() 
// function of Ds\map 
  
// Creating a Map 
$map = new \Ds\Map(["1" => 5,  
            "2" => 10, "3" => 15]); 
  
// Declare the callback function 
$callback = function($key, $value){ 
                return $value*10; 
            }; 
              
// Multiplying each value by 10 
// using callback function 
$map->apply($callback); 
  
print_r($map); 
  
?> 

Output:

Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => 1
            [value] => 50
        )

    [1] => Ds\Pair Object
        (
            [key] => 2
            [value] => 100
        )

    [2] => Ds\Pair Object
        (
            [key] => 3
            [value] => 150
        )

)