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pure virtual function in c++

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Alive Angelfish answered on August 4, 2020 Popularity 10/10 Helpfulness 3/10

answer pure virtual function in c++

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pure virtual function in c++

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#include <iostream>
#include  <string>
//Pure virtual function  or inteface allows us to define a function in a base class that doesn't have an implementation or definition in the base class and force sub classes to implement that function
//Pure virtual function is also called an interface in other languages
class Entity {
public:
	//virtual std::string GetName() { return "Entity"; }//This is a function that is just virtual .Overriding this function in sub class is optional we can instantiate subcllass without overriding  or implementing this function
	
	//Below is an example a Pure Virtual Function
	//It is an unimplemented function ant it forces the  sub class to implement it and define it
	//You will not be able to instantiate sub class without implementing or defining the function in sub class
	virtual std::string GetName() = 0; 
  //the pure virtual function must have virtual written at the beginning and =0 at the end
 //This function cannot contain any definition in base class,it is just a declaration
};
class Player :public Entity {
	std::string m_name;

public:
	Player(const std::string& name)
		:m_name(name)
	{};
	void Print() { std::cout << "This is Sub class" << std::endl; };
	std::string GetName()override { return m_name; };//Pure virtual functions is implemented here in this sub class
};
void PrintName(Entity* entity) {

	std::cout << entity->GetName() << std::endl;
}
int main()
{
	//Entity a;//We can't do this because class Entity contains function that is unimplemented
	Player x("Jacob");//This will work because we have implemented or defined the function in this sub class
	std::cin.get();
}

Popularity 10/10 Helpfulness 3/10 Language cpp

Source: Grepper

Tags: c++ function pure-virtual

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Contributed on Aug 05 2020

Alive Angelfish

0 Answers Avg Quality 2/10

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what is virtual function in c++

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// C++ program to illustrate
// concept of Virtual Functions
 
#include <iostream>
using namespace std;
 
class base {
public:
    virtual void print() { cout << "print base class\n"; }
 
    void show() { cout << "show base class\n"; }
};
 
class derived : public base {
public:
    void print() { cout << "print derived class\n"; }
 
    void show() { cout << "show derived class\n"; }
};
 
int main()
{
    base* bptr;
    derived d;
    bptr = &d;
 
    // Virtual function, binded at runtime
    bptr->print();
 
    // Non-virtual function, binded at compile time
    bptr->show();
 
    return 0;
}

Popularity 10/10 Helpfulness 3/10 Language cpp

Source: www.geeksforgeeks.org

Tags: c++

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Contributed on Jun 07 2023

Snehasish Dhar

0 Answers Avg Quality 2/10

virtual function in c++

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#include <iostream>
#include<string>
	//Virtual Functions are functions that allow us to override methods in subclasses
//In this example  we have an entity class as a base class and class player inherits from public entity 
class Entity {
public:
	virtual std::string GetName() { return "Entity"; }//It is a method in base class that we want to modify in sub class Player
	void Print() { std::cout << "This is Base class" << std::endl;}//function that is not virtual
};
class Player :public Entity {
	std::string m_name;

public:
	Player(const std::string& name)
		:m_name(name)
	{};
	void Print() { std::cout << "This is Sub class" << std::endl; };//function that is not virtual
	std::string GetName()override { return m_name; };//overriding the function in sub class
};

int main()
{
	Entity* e = new Entity();
	std::cout << e->GetName() << std::endl;
	Player* p = new Player("Jacob");
	std::cout << p->GetName() << std::endl;
	PrintName(p);// This function calls the GetName method from the Player instance despite it takes an entity instance as a parameter this is because player class is a sub  class of Entity and the method is marked virtual it will map with the method in the Player class and call it from there .It outputs => Jacob
	//if It was not virtual it would have called The method From Entity Instance and output would be => Entity
	Entity* notvirtualentity = new Entity();
	Player* notvirtualpalyer = new Player("XX");
	notvirtualentity =  notvirtualpalyer;
	notvirtualentity->Print();//It prints => this is base class if it was virtual function it would call print function from Player Class and print => This is subclass
	std::cin.get();
}

Popularity 10/10 Helpfulness 2/10 Language cpp

Source: Grepper

Tags: c++

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Contributed on Aug 04 2020

Alive Angelfish

0 Answers Avg Quality 2/10

C++ virtual function

Comment

class Base {
   public:
    void print() {
        // code
    }
};

class Derived : public Base {
   public:
    void print() {
        // code
    }
};

Popularity 10/10 Helpfulness 1/10 Language cpp

Source: Grepper

Tags: c++

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Contributed on Jun 13 2022

SAMER SAEID

0 Answers Avg Quality 2/10

pure virtual function in c++

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