Counter will not increment

Hello! In the code below, why does the counter not increment if I use Template arguments?

Code:

---

#include <iostream>

using namespace std;

struct parent
{
        int counter = 0;
        parent() {};
};

struct child : parent
{
        child() {};
};

template <typename A, typename B>
void f(A a, B b)
{
        b.counter += 1;
        cout << b.counter << endl;
}

int main()
{
        child Anne;
        child Pete;
       
        for (int i = 1; i <= 5; ++i)
        {
                f(Anne, Pete);
                f(Pete, Anne);
        }
        return 0;
}

---

It does increment: you keep copying the objects from main and then increment the counter of the copy.

Or, we can say that it doesn't increment the way you expected, and this has nothing to do with the use of templates: you merely forgot the basic rule about copying versus passing by reference.