Setting rightmost set bit of a number to zero.

set_rightmost_off.cpp

#include <iostream>
#include <cstdio>
using namespace std;
unsigned long set_rightmost_bit_off(unsigned long k)
{
	return k&(k-1);
}
int main()
{
	cout << set_rightmost_bit_off(6ul) << '\n';
  return 0;
}