3.cpp

#include <iostream> using namespace std;class Complex   {public:     Complex()   {real=0;imag=0;}      Complex(double r,double i)  {real=r;imag=i;}     Complex operator+(Complex &c2);     Complex operator+(int &i);    friend Complex operator+(int&,Complex &);       void display();   private:    double real;    double imag;   };Complex Complex::operator+(Complex &c) {return Complex(real+c.real,imag+c.imag);}   Complex Complex::operator+(int &i)   {return Complex(real+i,imag);}  void Complex::display() {cout<<"("<<real<<","<<imag<<"i)"<<endl;}   Complex operator+(int &i,Complex &c)   {return Complex(i+c.real,c.imag);}   int main() {Complex c1(3,4),c2(5,-10),c3;  int i=5;   c3=c1+c2; cout<<"c1+c2=";  c3.display();      c3=i+c1;  cout<<"i+c1=";   c3.display();  return 0;  }