Question

I can understand binary operation 11 & x, for example if x = 1011, the operation will take out 10 from x and left x to be 11. However, when it comes to hexadecimal, I am very confused. What is the math and reasoning behind the similar effect of 0xff & x? I can only understand this if I convert them all to binary.

Answer 1

0xFF & 0xABCD = 0xCD … why?

Because:
A = 1010
B = 1011
C = 1100
D = 1101

F = 1111

So the 0xFF = 0x00FF = 0000 0000 1111 1111
The 0xABCD           = 1010 1011 1100 1101 
                       ------------------- 
0xFF & 0xABCD        = 0000 0000 1100 1101

As with most things, once you work with hex for a while, you’ll learn some tricks for remembering the values.