how to count set bit in a number c++ code example

Example 1: Count set bits in an integer c++

//Method 1
	int count = __builtin_popcount(num);
//Method 2
	int count = 0;
    while (num) {
        count += num & 1;
        n >>= 1;
    }

Example 2: count bit 1 c++

returns the number of set bits in a integer.
cout<< __builtin_popcount (11); //1011
//Ouput: 3