PHP array_diff_ukey() Function

Hello folks! welcome back to a new edition of our tutorial on PHP. In this tutorial guide, we are going to be studying about the PHP array_diff_ukey() Function.

The array_diff_ukey() function compares only the keys of two or more arrays using a user defined function and returns an array containing the entries from array1 that are not present in array2, array3, etc.

This function is different from array_diff() function because the array_diff() function compares the values while this function compares the keys.

This PHP function is different from array_diff_assoc() because the PHP array_diff_assoc() function makes use of the internal algorithm to compare the keys and their values whereas this function makes use of the user defined functions.

Syntax

Following below is the syntax to use this function -

array_diff_ukey ( $array1, $array2 [, $array3...,callback $key_compare_func] );

READ: PHP array_diff_uassoc() Function

Parameter Details

Sr.No	Parameter & Description
1	array1(Required) The first array is the array that the others will be compared with.
2	array2(Required) It is an array to be compared with the first array
3	array3(Optional) It is an array to be compared with the first array
4	key_compare_func(Required) It is a callback function to use to compare the keys. This callback function must return an integer <, =, > than 0 if the first argument is considered to be respectively <, =, > than the second argument.

Return Value

This built-in PHP function returns an array containing all the entries from array1 that are not present in other arrays.

PHP Version

This function was first lunched as part of core PHP v 5.1.0.

Example1

Try out the below example -

<?php
   function key_compare_func($a, $b) {
      if ($a === $b) {
         return 0;
      }
      return ($a > $b)? 1: -1;
   }
   $input1 = array(0=>"banana", 1=>"orange", 2=>"grapes");
   $input2 = array(3=>"apple",1=>"apricot", 5=>"mango");

   print_r(array_diff_ukey($input1,$input2,"key_compare_func"));
?>

Output

When the above code is executed, it will produce the following result -

Array
(
    [0] => banana
    [2] => grapes
)

Example2

Try the following example -

<?php
   function key_compare_func($a, $b) {
      if ($a === $b) {
         return 0;
      }
      return ($a > $b)? 1: -1;
   }
   $input1 = array('blue'  => 1, 'red'  => 2, 'green'  => 3, 'purple' => 4);
   $input2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan'   => 8);

   print_r(array_diff_ukey($input1,$input2,"key_compare_func"));
?>

Output

When the above code is executed, it will produce the following result -

Array
(
    [red] => 2
    [purple] => 4
)

READ: PHP array_column() Function

Alright guys! This is where we are rounding up for this tutorial post. In our next tutorial guide, we are going to be discussing about the PHP array_fill() Function.

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