C++ program to implement a complex number class and its basic functions :

Complexclass2.cpp

#include<iostream>
    using namespace std;
    class cmplx{
        int real,img;
        public:
            cmplx(int x,int y);
            void add(cmplx a,cmplx b);
            void display();
    };
    cmplx::cmplx(int x=0,int y=0){
        real=x;
        img=y;
    }
    void cmplx::add(cmplx a,cmplx b){
        real=a.real+b.real;
        img=a.img+b.img;
    }
    void cmplx::display(){
        cout<<"The addition of two complex numbers is "<<real<<" + "<<img<<" i\n";
    }
    int main()
    {
        int x,y;
        cout<<"Enter the real and imaginary part of the first complex number..";
        cin>>x>>y;
        cmplx a(x,y);
        cout<<"Enter the real and imaginary part of the second complex number..";
        cin>>x>>y;
        cmplx b(x,y);
        cmplx c;
        c.add(a,b);
        c.display();
        return 0;
    }