Question

Given c is an int, I don’t understand what the statement c = c & (1 << bit) does. Any help is highly appreciated!

Answer 1

It masks out everything but the bit-th bit of c.

e.g. if c = 27 and bit = 3:

         c = 27 = 00011011 (binary)
(1 << bit) =  8 = 00001000
    result =      00001000 = 8

and when bit = 2:

         c = 27 = 00011011 (binary)
(1 << bit) =  4 = 00000100
    result =      00000000 = 0

Note that the result will either be equal to (1 << bit) (a power of 2) or 0.