运算符重载

根据以下代码段完善 ?? 处内容及程序内容，以实现规定的输出。

class Complex
{
    public:
        Complex(double r=0, double i=0):real(r), imag(i){    }
        Complex operator+( ?? ) const;//重载双目运算符'+'
        Complex operator-=( ?? ); //重载双目运算符'-='
        friend Complex operator-( ?? ) const;//重载双目运算符'-'
        void Display() const;
    private:
        double real;
        double imag;
};

void Complex::Display() const
{
    cout << "(" << real << ", " << imag << ")" << endl;
}

int main()
{
    double r, m;
    cin >> r >> m;
    Complex c1(r, m);
    cin >> r >> m;
    Complex c2(r, m);
    Complex c3 = c1+c2;
    c3.Display();
    c3 = c1-c2;
    c3.Display();
    c3 -= c1;
    c3.Display();
    return 0;
}

输入格式:

输入有两行，分别为两个复数的实部与虚部。

输出格式:

按样例格式输出结果。

输入样例:

在这里给出一组输入。例如：

4 2
3 -5

输出样例:

在这里给出相应的输出。例如：

(7, -3)
(1, 7)
(-3, 5)

 1 #include <iostream>
 2 using namespace std;
 3 class Complex
 4 {
 5     public:
 6         Complex(double r=0, double i=0):real(r), imag(i){    }
 7         Complex operator+( Complex &c2 ) const;//重载双目运算符'+'
 8         Complex operator-=( Complex&c2 ); //重载双目运算符'-='
 9         friend Complex operator-( Complex&c1,Complex&c2 ) ;//重载双目运算符'-'
10         void Display() const;
11     private:
12         double real;
13         double imag;
14 };
15 Complex Complex::operator +(Complex &c2)const
16 {
17     return Complex(real+c2.real,imag+c2.imag);
18 }
19 Complex Complex::operator -=(Complex&c2)
20 {
21     return Complex(real-=c2.real,imag-=c2.imag);
22 }
23 Complex operator -(Complex &c1,Complex &c2)
24 {
25     return Complex(c1.real-c2.real,c1.imag-c2.imag); 
26  }
27 void Complex::Display() const
28 {
29     cout << "(" << real << ", " << imag << ")" << endl;
30 }
31 
32 int main()
33 {
34     double r, m;
35     cin >> r >> m;
36     Complex c1(r, m);
37     cin >> r >> m;
38     Complex c2(r, m);
39     Complex c3 = c1+c2;
40     c3.Display();
41     c3 = c1-c2;
42     c3.Display();
43     c3 -= c1;
44     c3.Display();
45     return 0;
46 }