[C++] Function Overloading & Overriding

Overloading

• Name of the method must be same
• Return type can be same or not
• Number of the parameter should be different
• If the number of the parameter is same, the type of the parameter must be different

 

#include <iostream>
using namespace std;

void func(int i)
{
	cout << "func(int) is called." << endl ;
}

void func(char c)
{
	cout << "func(char) is called." << endl;
}

void func(int i, int j)
{
	cout << "func(int, int) is called." << endl;
}

/*
int func(int i)
{
	cout << "int func(int) is called." << endl;
}
*/

int main()
{
	func(1);
	func('a');
	func(2, 3);
}

 

 

You can declare overloading functions like this code.

 

But if you unlock the annotation there will be errors after.

 

Because 'Just a different return type is not allowed to overload a function'.

 

void func(int a) and int func(int a) is not overloaded fuctions.

 

 

 

 

 

 

Overriding

• Method that you override must be already declared in the base class
• Name of the method must be same
• The parameter of method must be same. (type and number of the parameter)
• Return type must be same
• Overrided method need to have something more or at least same with the base.

 

#include <iostream>
using namespace std;

class Base
{
public:
	void func()
	{
		cout << "B::func() is called" << endl;
	}
};

class Derived : public Base
{
public:
	void func()
	{
		cout << "D::func() is called" << endl;
		//Base::func();
	}
};

int main()
{
	Base b;
	Derived d;

	b.func();//result, B::func() is called
	d.func();//result, D::func() is called
}

 

Redefinition of a function to add what it needs and make something different from the based one.

 

(And of course you can call the base class's function like line19)

 

 

 

 

 

 

 

 

[참고자료]

- 윤성우의 열혈 C++ 프로그래밍