c++ XOR between bitsets

Question

std::bitset <1> a1;
std::bitset <1> a2;

a1 = std::bitset<1> (0);
a2 = std::bitset<1> (1);

std::bitset<1> b = (a1 ^= a2)

This results in

b = 1

which is fine but modifies also a1, which after the XOR operation becomes:

a1 = 1

Why is this happening? How can I avoid this without creating temp variables?

Answer 1

#include <iostream>
#include <bitset>
using namespace std;
int main()
{
    std::bitset <1> a1;
    std::bitset <1> a2;

    a1 = std::bitset<1>(0);
    a2 = std::bitset<1>(1);

    std::bitset<1> b = (a1 ^ a2);
    std::cout << b << std::endl;
    std::cout << a1 << std::endl;
    std::cout << a2 << std::endl;
    return 0;

}

Correct output: 1 0 1

#include <iostream>
#include <bitset>
using namespace std;
int main()
{
    std::bitset <1> a1;
    std::bitset <1> a2;

    a1 = std::bitset<1>(0);
    a2 = std::bitset<1>(1);

    std::bitset<1> b = (a1 ^= a2);
    std::cout << b << std::endl;
    std::cout << a1 << std::endl;
    std::cout << a2 << std::endl;
    return 0;

}

Correct output: 1 1 1 because ^=, so you change a1.

XOR is operator ^

Operator ^= is XOR with assignment