c++ 派生 class 访问基类的友元运算符

Question

I am working with operator overloading and inheritance. I currently have something similar to the following code:

istream& operator >> (istream& in, derived& d)
{
   /* Some code asking for input to populate the object's data members*/
   cin >> d; /*Here, the operator called is this one, creating an infinite loop*/
}

The base class has an istream >> operator and when trying to invoke it, the operator actually calls itself, causing a loop. How can I access the base's operator from the derived's?

Answer 1

You need to convert it to the base class to call the operator>> on base class, otherwise it would try to call itself and lead to infinite recursion. Eg

istream& operator >> (istream& in, derived& d)
{
    in >> static_cast<base&>(d);
    return in;
}

PS: You should use in instead of using cin fixedly, and return in in operator>> .