Question

When I was trying to learn from an existing program, I could not understand what the following two lines of code try to do?

for(i=0;0==(x&1);++i)x>>=1;


if(0==(x-=y)) return y<<i;

Any explanations would be appreciated.

Answer 1

for(i=0;0==(x&1);++i)x>>=1

Finds the least significant bit set to 1 in an integer

if(0==(x-=y)) return y<<i;

Subtracts y from x, and if the result is 0, returns y shifted over (toward the more significant bits) by i bits.