find the index of the highest bit set of a 32-bit number without loops obviously

Question

Here\'s a tough one(atleast i had a hard time :P):

find the index of the highest bit set of a 32-bit number without using any loops.

Answer 1

int high_bit_set(int n, int pos)
{
if(pos<0) 
return -1;
else
return (0x80000000 & n)?pos:high_bit_set((n<<1),--pos);
}

main()
{
int n=0x23;
int high_pos = high_bit_set(n,31);
printf("highest index = %d",high_pos);
}

From your main call function high_bit_set(int n , int pos) with the input value n, and default 31 as the highest position. And the function is like above.