Are 'addition' and 'bitwise or' the same in this case?

Question

Say I have four 32-bit numbers, defined so that their bits don\'t overlap, i.e.

unsigned long int num0 = 0xFF000000;
unsigned long int num1 = 0x00FF0000;
uns         


        

Answer 1

No:

num3 + num3 => 0x000001FE

num3 | num3 => 0x000000FF

Of course, as long as you ensure that you only add things together where you know that they don't have the same bits set, you should be safe.