C++ Remove rightmost set bit


Example

C-style bit-manipulation

template <typename T>
T rightmostSetBitRemoved(T n)
{
    // static_assert(std::is_integral<T>::value && !std::is_signed<T>::value, "type should be unsigned"); // For c++11 and later
    return n & (n - 1);
}

Explanation

  • if n is zero, we have 0 & 0xFF..FF which is zero
  • else n can be written 0bxxxxxx10..00 and n - 1 is 0bxxxxxx011..11, so n & (n - 1) is 0bxxxxxx000..00.