1 #include 
     
       2 using namespace std; 3  4 class Good 5 { 6 public: 7     int member; 8     Good(int a): member(a) 9     {10         cout << "调用构造" << endl;11     }12     void show()13     {14         cout << member << endl;15     }16     Good operator+(const Good& obj)17     {18         return Good(member - obj.member);19     }20     21     friend ostream& operator<<(ostream& os, Good& obj)22     {23         os << obj.member << "运算符重载" << endl;24         25         return os; //这句话关键，便于重复调用 26     }27 };28 29 int main(int argc, char *argv[])30 {31     Good a(10), b(20);32     Good c = a + b;33     cout << c;34     c.show();35     return 0;36 }