Question

I have three arrays:

$arr_1 = array('a'=>1,'b'=>2);  
$arr_11 = array('a'=>1, 'd'=>4);  
$arr_2 = array('a'=>'aaa','b'=>'bbb', 'c'=>'ccc');  

I want to check that all keys from $arr_1 exist in $arr_2.

someFunction($arr_1,$arr_2); //return true  
someFunction($arr_11,$arr_2); //return false 

I know how to do it with a “foreach” loop.
Is there a better way?

Answer 1

maybe

<?php

array_diff(array_keys($arr_1), array_keys($arr_11));

?>

shorter yes, faster dunno 🙂

Update from @deceze

<?php 

array_diff_key($arr_1, $arr_11);

?>