Binary Operator Overloading in C++

Program 1

// Operator overloading 
#include<iostream>
using namespace std;
class TestAdd
{
    int n;
    public:
     TestAdd(int n)
     {
        this->n=n;
     }
     TestAdd()
     {
        n=0;
     }
     void display();
     TestAdd operator+(TestAdd K);
     TestAdd operator-(TestAdd K);
};
void TestAdd::display()
{
    cout<<n<<endl;
}
TestAdd TestAdd::operator+(TestAdd K)
{
      TestAdd temp;
      temp.n=n+K.n;
      return temp;
}

TestAdd TestAdd::operator-(TestAdd K)
{
      TestAdd temp;
      temp.n=n-K.n;
      return temp;
}

int main()
{
    system("cls");
    TestAdd T1(50);  
    TestAdd T2(30);
    TestAdd T3;
    T1.display();
    T2.display();
    T3.display();
    T3=T1+T2;    // T3=T1.operator+(T2)
    cout<<"\nAddition is :";
    T3.display();
    T3=T1-T2;    // T3=T1.operator-(T2)
    cout<<"\nSubtraction is :";
    T3.display();

    return 0;
}

Program 2

// Operator overloading 
#include<iostream>
using namespace std;
class TestAdd
{
    int n;
    public:
     TestAdd(int n)
     {
        this->n=n;
     }
     TestAdd()
     {
        n=0;
     }
     TestAdd operator+(int m);
     TestAdd operator-(int m);
     void display();
};
TestAdd TestAdd::operator+(int m)  //m=20
{
      TestAdd temp;
      temp.n=n+m;
      return temp;
}
TestAdd TestAdd::operator-(int m)  //m=20
{
      TestAdd temp;
      temp.n=n-m;
      return temp;
}
void TestAdd::display()
{
     cout<<endl<<n<<endl;
}

int main()
{
    system("cls");
    TestAdd T1(50);
    TestAdd T2;
    T2=T1+20;  // T2=T1.operator+(20)
    T2.display();
      T2=T1-20;  // T2=T1.operator-(20)
      T2.display();
    return 0;
}