Which will print the following code:

#include <iostream>

using namespace std;

class A {
    int i;
public:
    A() {
        cout << "in A::A()" << endl;
        i = 0;
    }
    A operator = (A a) {
        cout << "in A::operator=(A)" << endl;
        i = a.i;
    }
};

int main() {
    A a;
    A b = a;
    return 0;
}

```
in A::A()
```
```
in A::operator=(A)
```
```
in A::A()
in A::operator=(A)
```
Compilation error
Runtime error

Explanation

if A b = a;, the automatically generated copy constructor is called instead of the assignment operator, so the assignment operator cannot output anything because it is never called.