CODEWITHSUNDEEP
c++class
신한슬
신한슬

Reputation: 309

Using polymorphism to copy derived class' value to the base class

English is not my first language. I hope I will not make lot of mistakes. I'll try my best to be as clear as possible!

I have a base class

class engine
{
private :
    std::string name;
    double weight;

public:
    engine();
    ~engine();
    std::string getName() const;
    int getWeight() const
};

std::string engine::getName() const{
return this->name;
}

int engine::getWeight() const{
return this->weight;
}

and derived class

class diesel : public engine
{
private:
    std::string name;
    double weight;

public:
    diesel();
    ~diesel();
};

diesel::diesel(){
this->name = Diesel;
this->weight = 500.00;
}

In my main.cpp

int main()
{
      diesel diesel_engine; 
      const engine &e = diesel_engine;
      std::cout<<e.getWeight()<<e.getName()<<std::endl;
      return 0;
}

1- I must construct a diesel class named diesel_engine.

2- pass diesel_engine's value to a new engine by reference??

When I call const engine &e = diesel_engine;, diesel_engine's value(name and weight) should be copied to the new engine e.

So 'e' should have weight of 500.00 and the name "Diesel".

I don't get how can I use polymorphism to do that.

Thank you for reading this question!

Upvotes: 0

Views: 36

Answers (1)

Samer Tufail
Samer Tufail

Reputation: 1894

Lets start with the class declarations

class Engine
{
private:
    float weight_;
    std::string name_;
public:
    Engine(float weight, std::string name) : weight_(weight), name_(name){};
    std::string GetName() const { return name_;}
};

class Diesel : public Engine
{
public:
  Diesel(float weight, std::string name) : Engine(weight, name){} 
};

So what we have here is an Engine class which is our base class and then we define our Diesel class, Diesel inherits from Engine and passes the arguments to its base class.

Now to use this:

Diesel disel_engine(0.0, "diesel engine");
const Engine& eng = disel_engine;
cout << eng.GetName();

The call to eng.GetName() prints the correct engine name

Demo Here

Upvotes: 1

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