C++ Program For Constructor Overloading

Program 1

//Program by call by reference
#include<iostream>
#define clrscr() system("cls")
using namespace std;
class Test
{
      int a,b,c,d;
      public:
      Test(int x,int y,int z)
      {
       cout<<"\nConstructor with  3  argument";
        a=x;
        b=y;
        c=z;
        } 
      Test(int x,int y)
      {
        cout<<"\nConstructor with  2 argument";
        a=x;
        b=y;
        c=100;
        }
     Test(int x)
      {
        cout<<"\nConstructor with  1 argument";
        a=x;
        b=50;
        c=100;
        }   
      Test()
      {
        cout<<"\nConstructor without argument";
        a=b=c=0;
      }
      public:
      void add();
      void sub();
};
void Test::add()
{
    d=a+b+c;
    cout<<"\nAddition is: "<<d;
}
void Test::sub()
{
    d=a-b-c;
    cout<<"\nsubtraction is: "<<d;
}
int main()
{
     clrscr();
     Test T1(50,30,20);
     Test T2(10,20);
     Test T3(5); 
     Test T4;
     T1.add();
     T2.add();
     T3.add();
     T4.add();

     T1.sub();
     T2.sub();
     T3.sub();
     T4.sub();
   return 0;
}