PHP
Find Differences Between Two Arrays by Value
Learn to efficiently compare two arrays and find values present in the first array but not in the second, using PHP's array_diff function.
$array1 = ['apple', 'banana', 'orange', 'grape'];
$array2 = ['banana', 'grape', 'kiwi'];
$difference = array_diff($array1, $array2);
print_r($difference);
// Output: Array
// (
// [0] => apple
// [2] => orange
// )
How it works: The `array_diff()` function compares `array1` against `array2` (and optionally more arrays) and returns an array containing all the values from `array1` that are not present in any of the other arrays. This is highly useful for identifying unique items or changes between two datasets, such as comparing a user's selected options against a default list.