Get the difference of two arrays of objects by comparing values from a particular column/property

Question

I know there is array_diff and array_udiff for comparing the difference between two arrays, but how would I do it with two arrays of objects?

array(4) {
    [0]=>
        object(stdClass)#32 (9) {
            ["id"]=>
            string(3) "205"
            ["day_id"]=>
            string(2) "12"
        }
}

My arrays are like this one, I am interested to see the difference of two arrays based on id column values.

Answer 1

This is exactly what array_udiff is for. Write a function that compares two objects the way you would like, then tell array_udiff to use that function. Something like this:

function compare_objects($obj_a, $obj_b) {
  return $obj_a->id - $obj_b->id;
}

$diff = array_udiff($first_array, $second_array, 'compare_objects');

Or, if you're using PHP >= 5.3 you can just use an anonymous function instead of declaring a function:

$diff = array_udiff($first_array, $second_array,
  function ($obj_a, $obj_b) {
    return $obj_a->id - $obj_b->id;
  }
);