Question

I have written a template function like this:

template <class T>
const T& max1(const T& x, const T& y)
{
  if(y < x)
    return x;
  return y;
}

Now, how can I use this function to compare two objects of class A where class A is like the following?

class A
{
public:
    A(int x){i=x;}


private:

    friend bool operator<(A const& lhs, A const& rhs) 
    {
        return lhs.i < rhs.i;
    }

int i;

};


I believe I have to overload < operator but could not figure out how this whole process is working? Could you also provide a link to articles where I can read about this?

Thank you.

Answer 1

Defining an overloaded < operator is simple in this case:

bool operator<(A const& lhs, A const& rhs) {
    return lhs.i < rhs.i;
}

In general, defining overloaded operators is as simple as that (though if you want to access non-public members, you will need to friend the function within the class’s definition).

Some operator overloads (like [], (), =) cannot be defined as free functions, but instead must be member functions. This isn’t any harder than defining free-function overloaded operators, but is something to be aware of.