PHP array_diff_key() Function

PHP array_key_first() Function

Last Updated : 22 Jul, 2022

The array_key_first() function is an inbuilt function in PHP that is used to get the first key of an array. This function returns the first key without affecting the internal array pointer.

Syntax:

int|string|null array_key_first(array $array)

Parameters: This function accepts a single parameter $array that holds the array.

Return Value: This function returns the first key of the array if the array is not empty, and null otherwise.

Example 1:

PHP

<?php 
  
$arr = array(); 
  
var_dump(array_key_first($arr)); 
  
$arr1 = array("10", "20", "30", "40", "50"); 
var_dump(array_key_first($arr1)); 
  
?>

Output:

NULL
int(0)

Example 2:

PHP

<?php 
  
$arr = array( 
    'Geeks'  => "HTML",  
    'GFG'  => "CSS",  
    'Geek'  => "JavaScript",  
    'G4G' => "PHP"
); 
  
var_dump(array_key_first($arr)); 
  
$arr1 = array( 
    5 => "geeks", 
    10 => "GFG"
); 
  
var_dump(array_key_first($arr1)); 
  
?>

Output:

string(5) "Geeks"
int(5)

Reference: https://www.php.net/manual/en/function.array-key-first.php

PHP array_diff_key() Function

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