How to remove a key and its value from an associative array in PHP ?

Given an associative array containing array elements and the task is to remove a key and its value from the associative array.

Examples:

Input : array( "name" => "Anand", "roll"=> "1")
Output : Array (
    [roll] => 1
)

Input : array( "1" => "Add", "2" => "Multiply", "3" => "Divide")
Output : Array (
    [2] => Multiply
    [3] => Divide
)

Method 1: Using unset() function: The unset() function is used to unset a key and its value in an associative array.

Syntax:

void unset( $array_name['key_to_be_removed'] )

Program:

<?php

// Declare an associative array
$arr = array(
    "1" => "Add",
    "2" => "Multiply",
    "3" => "Divide"
);

// Remove the key 1 and its value
// from associative array
unset($arr['1']);

// Display the array elements
print_r($arr);

?>

Output:

Array
(
    [2] => Multiply
    [3] => Divide
)

Method 2: Using array_diff_key() function: This function is used to get the difference between one or more arrays. This function compares the keys between one or more arrays and returns the difference between them.

Syntax:

array array_diff_key( $array_name, array_flip((array) ['keys_to_be_removed'] )

Program:

<?php

// Declare an associative array
$arr = array(
    "1" => "a",
    "2" => "b",
    "3" => "c"
);

// Remove the key 1 and its value
// from associative array
$result = array_diff_key($arr,
            array_flip((array) ['1']));

// Display the result
print_r($result);

?>

Output:

Array
(
    [2] => b
    [3] => c
)