运算符重载、成员函数和友元函数举例（复数）

源程序：

#include <iostream>
using namespace std;class myComplex
{
private:
  double real, imag;
public:
  myComplex();
  myComplex(double r, double i);
  void outCom();
  myComplex operator-(const myComplex& c);
  friend myComplex operator+(const myComplex& c1, const myComplex& c2);
};myComplex::myComplex()
{
  real = 0;
  imag = 0;
}
myComplex::myComplex(double r, double i)
{
  real = r;
  imag = i;
}
void myComplex::outCom()
{
  cout << "(" << real << "," << imag << ")";
}myComplex myComplex::operator-(const myComplex& c)
{
  return myComplex(this->real - c.real, this->imag - c.imag);
}myComplex operator+(const myComplex& c1, const myComplex& c2)
{
  return myComplex(c1.real + c2.real, c1.imag + c2.imag);
}int main()
{
  myComplex c1(1, 2), c2(3, 4), res;
  c1.outCom();
  cout << "operator+";
  c2.outCom();
  cout << "=";
  res = c1 + c2; //调用运算符重载函数
  res.outCom();
  cout << endl;
  c1.outCom();
  cout << "operator-";
  c2.outCom();
  cout << "=";
  res = c1 - c2; //调用运算符重载函数
  res.outCom();
  cout << endl;
  return 1;
}