Handling Array Equality in PHP
If you want to check if two arrays contain the same values, regardless of order, you will have some issue using the operators == and ===.
With the equal operator == you are able to check for equality based on the type coerced values and keys (regardless of order).
[1, 2, 3] == [1, 2, 3] // true
[1, 2, 3] == [1, 2, '3'] // true
[1, 2, 3] == [1, 3, 2] // false
[1, 2, 3] == [0 => 1, '2' => 3, 1 => 2] // true
With the identical operator === you are able to check for equality based on the type and exact ordering of the keys.
[1, 2, 3] === [1, 2, 3] // true
[1, 2, 3] === [1, 2, '3'] // false
[1, 2, 3] === [1, 3, 2] // false
[1, 2, 3] === [0 => 1, 2 => 3, 1 => 2] // false
This is not always what you desire, treating the collection as a Set, you do not wish to validate the position of the element, only its’ presence. However, this can be resolved by using the following functions.
function array_values_equal($a, $b) {
$x = array_values($a);
$y = array_values($b);
sort($x);
sort($y);
return $x == $y;
}
function array_values_identical($a, $b) {
$x = array_values($a);
$y = array_values($b);
sort($x);
sort($y);
return $x === $y;
}
array_values_equal(['1', 2, 3], [3, 2, 1]) // true
array_values_identical([1, 2, 3], [3, 2, 1]) // true