Question

C++ Programming Coding

Thank you

-Suppose a car has an identifier (carid) and consists of an engine(Engine) and a body (Body).

-Engine is an integer type and has engine number (engineNo) and string type engine name (engineName).

-Body is an integer type and has a body number (bodyNo) and a string type body name (bodyName).

-Write a program that creates a Car object and copies that object.

(In both cases below, print the original and a copy to check the results.)

—Shallow copy

—Deep copy

Answer 1

An object copy is a process where a data object has its attributes copied to another object of the same data type.

Shallow Copy :

1. Shallow copying is creating a new object and then copying the non static fields of the current object to the new object. If the field is a value type, a bit by bit copy of the field is performed. If the field is a reference type, the reference is copied but the referred object is not, therefore the original object and its clone refer to the same object. A shallow copy of an object is a new object whose instance variables are identical to the old object.
2. The situations like , if you have an object with values and you want to create a copy of that object in another variable from same type, then you can use shallow copy, all property values which are of value types will be copied, but if you have a property which is of reference type then this instance will not be copied, instead you will have a reference to that instance only.

Deep Copy :

1. Deep copy is creating a new object and then copying the non-static fields of the current object to the new object. If a field is a value type, a bit by bit copy of the field is performed. If a field is a reference type, a new copy of the referred object is performed. A deep copy of an object is a new object with entirely new instance variables, it does not share objects with the old.

#include <iostream>
using namespace std;

class Engine {
    public:
    int engineNo;
    string engineName;
    
    Engine(int engineNo, string engineName){
        this->engineNo = engineNo;
        this->engineName = engineName;
    }
    
    Engine(Engine *engine){
        this->engineNo = engine->engineNo;
        this->engineName = engine->engineName;
    }
    
    void print(){
        cout<<"engineNo : "<<engineNo<<" ";
        cout<<"engineName : "<<engineName;
    }
};

class Body {
    public:
    int bodyNo;
    string bodyName;
    
    Body(int bodyNo, string bodyName){
        this->bodyNo = bodyNo;
        this->bodyName = bodyName;
    }
    
    Body(Body *body){
        this->bodyNo = body->bodyNo;
        this->bodyName = body->bodyName;
    }
    
    void print(){
        cout<<"bodyNo : "<<bodyNo<<" ";
        cout<<"bodyName : "<<bodyName<<"\n";
    }
};

class Car {
    int carId;
    Engine *engine;
    Body *body;
    
    public: 
    Car(int carId, Engine *engine, Body *body){
        this->carId = carId;
        this->engine = engine;
        this->body = body;
    }
    
    Car(Car *car){
        this->carId = car->carId;
        this->engine = new Engine(car->engine);
        this->body = new Body(car->body);
    }
    
    void print(){
        cout<<"CarId "<<carId;
        cout<<"\nEngine ";
        cout<<" stored at memory address : "<<engine<<"\n";
        engine->print();
        cout<<"\nBody ";
        cout<<" stored at memory address : "<<body<<"\n";
        body->print();
    }
};

int main()
{
    Engine *engine = new Engine(1,"engine1");
    Body *body = new Body(1,"body1");
    Car *car = new Car(1, engine, body);
    car->print();
    
    cout<<"COPYING CAR TO CAR1 USING SHALLOW COPY\n";
    cout<<"content of car1\n";
    Car *car1 = car;
    car1->print();
    
    
    cout<<"COPYING CAR TO CAR2 USING DEEP COPY\n";
    cout<<"content of car2\n";
    Car *car2 = new Car(car);
    car2->print();
    return 0;
}

Output :

Notice :
1. In case of shallow copy address of engine and body of car1 and car is same.
2. In case of deep copy address of engine and body of car2 and car are different

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