Modifying reference member from const member function in C++

Question

I am working on const-correctness of my code and just wondered why this code compiles:

class X
{
    int x;
    int& y;
public:
    X(int& _y):y(_y)
         


        

Answer 1

As additional information for the accepted answer, I want to say, in fact one can change variables in X.

Because you are not changing any variable in X.

#include 
#include 
#include 
using namespace std;

class Bar {
public:
    void funcA() const {
        c++;
    }

    int b = 3;
    int &c = b;
};

int main()
{
    Bar b;
    b.funcA();
    cout << b.b << endl;  //4
}

So the main idea for this problem is:

It modifies what the member refers to, it does not modify the member.

This also applies for pointer members.

See here Why can reference members be modified by const member functions?