例10.7 在例10.2的基礎(chǔ)上，用重載的“<<”輸出復(fù)數(shù)。 
#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);                    //運(yùn)算符“+”重載為成員函數(shù)
friend ostream& operator << (ostream&,Complex&);     //運(yùn)算符“<<”重載為友元函數(shù)
private:
double real;
double imag;
};

Complex Complex∷operator + (Complex &c2)               //定義運(yùn)算符“+”重載函數(shù)
{return Complex(real+c2.real,imag+c2.imag);}
ostream& operator << (ostream& output,Complex& c)       //定義運(yùn)算符“<<”重載函數(shù)
{output<<″(″<<c.real<<″+″<<c.imag<<″i)″<<endl;
return output;
}

int main( )
{Complex c1(2,4),c2(6,10),c3;
c3=c1+c2;
cout<<c3;
return 0;
}
(在Visual C++ 6.0環(huán)境下運(yùn)行時(shí)，需將第一行改為#include <iostream.h>，并刪去第2行。)