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 IDs.
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;
}
);
Answer：
And here is another option if you wanna compare string properties (e.g. name):
$diff = array_udiff($first_array, $second_array,
function ($obj_a, $obj_b) {
return strcmp($obj_a->name, $obj_b->name);
}
);
Answer：
Here’s another option, if you want to run the diff according to object instances. You would use this as your callback to array_udiff:
function compare_objects($a, $b) {
return strcmp(spl_object_hash($a), spl_object_hash($b));
}
You’d only want to use that if you’re certain that the arrays both contain only objects – here’s my personal use case.
