How to get position of right most set bit in C

Question

int a = 12;

for eg: binary of 12 is 1100 so answer should be 3 as 3rd bit from right is set.

I want the position of the last most set bit o

Answer 1

1- Subtract 1 form number: (a-1)

2- Take it's negation : ~(a-1)

3- Take 'AND' operation with original number:

int last_set_bit = a & ~(a-1)

The reason behind subtraction is, when you take negation it set its last bit 1, so when take 'AND' it gives last set bit.