C program to set k lower order bits

Question

For a 32 bit integer, how do I set say k low order bits in C?

Answer 1

Assuming you want to set the k lowest bits of a 32-bit integer x, I believe this will work:

if( k > 0 ) {
    x |= (0xffffffffu >> (32-k))
}

Answer 2

To set n least significant bits in k, you could use arithmetic:

k |= (1 << n) - 1;

(Provided n is less or equal your int size in bits.)

Answer 3

something along the lines of

set k lower bits:

while (k) {
    k--;
    num |= (1<<k);
}

Is that what you meant?