How to learn PHP array_diff_key_PHP tutorial

How to learn PHP array_diff_key

Definition and usage

The array_diff_key() function returns an array containing all keys that are in the compared array but are not in any other parameter array.

Grammar

array_diff_key(array1,array2,array3...)

Parameters

Description

array1 required. The first array to compare with other arrays.

array2 required. The array to compare to the first array.

array3 is optional. The array to compare to the first array. There can be multiple.

Tips and Notes

Tip: You can compare one or more arrays with the first array.

Note: Only key names are used for comparison.

Example

"Cat",1=>"Dog",2=>"Horse"); $a2=array(2=>"Bird", 3=>"Rat",4=>"Fish"); $a3=array(5=>"Horse",6=>"Dog",7=>"Bird"); print_r(array_diff_key ($a1,$a2,$a3)); ?>

Output:

Array ( [0] => Cat [1] => Dog )