PHP | Ds\Map apply() Function

The 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:

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 apply() function of Ds\Map:

Program 1:

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<?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);
  
?>

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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:

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<?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);
  
?>

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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
        )

)


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