How to do an operator overload for a class template method

Question

I am having trouble avoiding errors when trying to overload operators in my class's cpp file. I have tried many variations but cannot get the right syntax.

Currently I have this, which has an error "deduced class type 'TreeSet' in function return type".

// cpp file
template <typename T>
TreeSet TreeSet<T>::operator+(const TreeSet &other) {}

The function was declared as this, where the class is a template with typename T. I am also not allowed to change anything in the header file.

// header file
TreeSet operator+(const TreeSet &other);

I tried specifying the template type for the return type and/or the parameter, neither of which provided a solution.

Answer 1

The compiler cannot deduce the class type 'TreeSet' in the return type of your function, because the template parameter 'T' is missing.

You just need to do this:

template <typename T>
TreeSet<T> TreeSet<T>::operator+(const TreeSet &other) {
    // Your implementation here
}