Excluding Certain Results

[RandallK]

I have an array with numbers 1 and 3.

I have a second array with numbers 1-5.

I want to find all numbers in the second array that are NOT a part of the first (2, 4 and 5). What is the best way to accomplish this?

[astupidname]

$a1 = array(1,3);
$a2 = array(1,2,3,4,5);
print_r(array_diff($a2,$a1));