CODEWITHSUNDEEP
c++polymorphismoverloading
Jayraj Srikriti Naidu
Jayraj Srikriti Naidu

Reputation: 99

C++ polymorphism and overloading?

Can overloading be considered as an implementation of polymorphism? If they are the same then why are two different words used?

Upvotes: 3

Views: 4113

Answers (2)

Cheers and hth. - Alf
Cheers and hth. - Alf

Reputation: 145204

Yes, overloading is a form of static polymorphism (compile time polymorphism). However, in C++ the expression “polymorphic class” refers to a class with at least one virtual member function. I.e., in C++ the term “polymorphic” is strongly associated with dynamic polymorphism.

The term override is used for providing a derived class specific implementation of a virtual function. In a sense it is a replacement. An overload, in contrast, just provides an ¹additional meaning for a function name.

Example of dynamic polymorphism:

struct Animal
{
    virtual auto sound() const
        -> char const* = 0;
};

struct Dog: Animal
{
    auto sound() const
        -> char const* override
    { return "Woof!"; }
};

#include <iostream>
using namespace std;

auto main()
    -> int
{
    Animal&& a = Dog();
    cout << a.sound() << endl;
}

Example of static polymorphism:

#include <iostream>
using namespace std;

template< class Derived >
struct Animal
{
    void make_sound() const
    {
        auto self = *static_cast<Derived const*>( this );
        std::cout << self.sound() << endl;
    }
};

struct Dog: Animal< Dog >
{
    auto sound() const -> char const* { return "Woof!"; }
};

auto main()
    -> int
{ Dog().make_sound(); }

Notes:
¹ Except when it shadows the meanings provided by a base class.

Upvotes: 8

imreal
imreal

Reputation: 10348

Yes, overloading is a form of static polymorphism, Ad hoc polymorphism to be precise.

It is NOT dynamic polymorphism (Subtyping), which is what people usually refer to in the context of C++.

https://en.wikipedia.org/wiki/Polymorphism_(computer_science)

Upvotes: 3

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