I need to compare 2 arrays: Array_A and Array_B. I then want to assign to Array_A the values found in Array_B (without deleting what's already in Array_A) IF and ONLY IF the values found in Array_B are not already in Array_A.

In my mind, I'm thinking I need to use 2 FOREACH loops, but then I came across array_dif() and in_array()...

Advice is appreciated... Which approach should I use?