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

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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); 
  
?> 