c++ 运算符重载

/*
运算符重载,类型转换函数，转换构造函数
无参默认构造函数，带参初始化构造函数，
*/
#include <iostream.h>
//#include <iostream>
#include <cstdlib>
//using namespace std;
class Complex
{
 public:
     Complex( ) { real = 0; imag = 0; } //无参默认构造函数
    //Complex(double r) { real = r; imag = 0;} 转换构造函数
     Complex(double r, double i) { real = r; imag = i;} //带参构造函数
     operator double( ) { cout<<"real = "<<real;return real;} //类型转换函数
    friend Complex operator +(Complex c1, Complex c2); //运算符重载
    void display( );
 private:
    double real;
    double imag;
};

Complex operator +(Complex c1, Complex c2)
{
  return Complex(c1.real + c2.real, c1.imag + c2.imag);
}

void Complex::display( )
{
  cout<<"("<<real<<","<<imag<<"i)"<<endl;
}

int main( )
{
  Complex c1(3,4), c2(5,-10), c3;
  double t = c1 + 2.5;
  cout<<"t = "<<t<<endl;
  c3.display( );
  c3 = c1 + c2;
  c3.display();
  system("pause");
  return 0;
}