Verify value is UNIQUE in list

[phppup]

I have a list of items and want to verify that each is unique before doing further processing to the list.

Is there a built-in function or simple method to verify this?

My thought was to put each item into an array and then create a function to run through each element compared to the entire list, but that seems a bit cumbersome.

Any better alternatives?

[Barand]

$arr = [ 1, 2, 3, 1, 4, 5, 2, 6, ];

$arr2 = array_unique($arr);                 // to force a unique set of values

$arr3 = array_count_values($arr);           // to verify they are all unique