Question

**** IN C++ *****

1.Given the class alpha and the main function, modify the class alpha so the main function is working properly.

#include <iostream>
using namespace std;
////////////////////////////////////////////////////////////////
class alpha
{
private:
int data;
public:
//YOUR CODE

};
////////////////////////////////////////////////////////////////
int main()
{
alpha a1(37);
alpha a2;

a2 = a1;
cout << "\na2=";
a2.display(); //display a2

alpha a3(a1); //invoke copy constructor
cout << "\na3=";
a3.display(); //display a3
alpha a4 = a1;
cout << "\na4=";
a4.display();
cout << endl;
return 0;
}

Answer 1

#include <iostream>
using namespace std;
class alpha
{
private:
int data;
public:

//this is for alpha a2; this object creation if we remove it will raise an error.It is default constructor.
alpha(){;}

//this if for alpha a1(37); and it is a parameterized constructor with one parameter as integer type.
alpha(int d){

//assigning value to object.
   data=d;
}

//copy constructor. And this is for alpha a3(a1); and alpha a4=a1; these two lines.
alpha(const alpha &a){
   data=a.data;
}

//display function to display value of objects.
void display(){

//displaying data value of particular object invoked from main()
   cout<<data;
}
};
int main()
{
alpha a1(37); //invoking parameterized constructor
alpha a2;  //invoke default constructor
a2=a1; //invoke copy constructor
cout << "\na2=";
a2.display(); //display a2
alpha a3(a1); //invoke copy constructor
cout << "\na3=";
a3.display(); //display a3
alpha a4 = a1; //invoke copy constructor
cout << "\na4=";
a4.display(); //display a4
cout << endl;
return 0;
}

output:-

a2=37
a3=37
a4=37