Find whether a number is power of two

1. A simple method for this is to simply take the log of the number on base2,if you get an integer then number is power of 2.

2. Another solution is to keep dividing the number by two, i.e, do n = n/2 iteratively. In any iteration, if n%2 becomes non-zero and n is not 1 then n is not a power of 2. If n becomes 1 then it is a power of 2.

#include
#define bool int
/* Function to check if x is power of 2*/
bool isPowerOfTwo(int n)
{
  if(n == 0)
    return 0;
  while(n != 1)
  {
    n = n/2;
    if(n%2 != 0 && n != 1)
      return 0;
  }
  return 1;
}
/*Driver program to test above function*/
int main()
{
  int test_no = 31;
  if(isPowerOfTwo(test_no))
    printf("%d is a power of 2", test_no);
  else
    printf("%d is not a power of 2", test_no);
  getchar();
}
3. All power of two numbers have only one bit set. So count the no. of set bits and if you get 1 then number is a power of 2.