PHP : array_diff_key() function

Last update on August 19 2022 21:51:17 (UTC/GMT +8 hours)

PHP: Computes the difference of arrays using keys for comparison

The array_diff_key() function is used to compare the keys from an array against the keys from another array and returns the difference. This function is like array_diff() except the comparison is done on the keys instead of the values.

Version:

(PHP 4 and above)

Syntax:

array_diff(array1, array2, array3 ...)

Parameter:

Name	Description	Required / Optional	Type
array1	The specified array which will be compared with other arrays.	Required	Array
array2	Compared with the first array.	Required	Array
array3	Compared with the second array.	Optional	Array

Return value:

An array containing all the entries from array1 whose keys are not present in any of the other arrays i.e. array2, array3 etc..

Value Type: Array

Example:

<?php
$array1 = array('Math'=>77, 20, 'Geography'=>89, 'Language'=>67);
$array2 = array('Language'=>71, 'Science'=>91 ,20, 'Geography'=>89);
var_dump(array_diff_key($array1, $array2));
?>

Output:

array(1){["Math"]=> int(77) }

Pictorial Presentation:

php function reference: array_diff_key() function

View the example in the browser

Practice here online:

PHP: Tips of the Day

Filters the collection using the given callback

Example:

<?php
function tips_reject($items, $func)
{
  return array_values(array_diff($items, array_filter($items, $func)));
}

print_r(tips_reject(['Apple', 'Pear', 'Kiwi', 'Banana'], function ($item) {
  return strlen($item) > 4;
}));
?>

Output:

Array
(
    [0] => Pear
    [1] => Kiwi
)