例10.2 改寫例10.1，重載運算符“+”，使之能用于兩個復數相加。
#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);               //聲明重載運算符的函數
void display( );
 private:
double real;
double imag;
};
Complex Complex∷operator+(Complex &c2)          //定義重載運算符的函數
{ Complex c;
c.real=real+c2.real;
c.imag=imag+c2.imag;
return c;}

void Complex∷display( )
{ cout<<″(″<<real<<″,″<<imag<<″i)″<<endl;}

int main( )
{ Complex c1(3,4),c2(5,-10),c3;
c3=c1+c2;                                     //運算符+用于復數運算
cout<<″c1=″;c1.display( );
cout<<″c2=″;c2.display( );
cout<<″c1+c2=″;c3.display( );
return 0;
}