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Count number of bits to be flipped to convert A to B

Problem: Given two numbers A and B. Write a program to count number of bits needed to be flipped to convert A to B.

For example: 
Input: A = 12 and B = 22
Output: 3

Binary representation of 12 is 001100
Binary representation of 22 is 010110

Here we need to flip 3 bits in A to convert it to B.

Input: A = 10 and B = 20
Output: 4

Binary representation of 10 is 001010
Binary representation of 20 is 010100

Here we need to flip 4 bits in A to convert it to B.
Approach: Here we will use XOR operator to calculate our result.
  • Calculate XOR of A and B. 
    • x = A ^ B 
  • Count the set bits in x calculated above. 
Following is the implementation of above approach: 
#include <bits/stdc++.h>
using namespace std;

/* function to calculate number of flips */
int numFlip(int A, int B)
{
    /* A xor B */
    int x = A ^ B;

    int count = 0;
    while(x)
    {
        count += x & 1;
        x >>= 1;
    }
    return count;
}

/* driver function */
int main()
{
    int A, B;

    A = 12; B = 22;
    cout<<numFlip(A, B)<<"\n";

    A = 10; B = 20;
    cout<<numFlip(A, B)<<"\n";

    return 0;
}
Output: 
3
4