7-1 复数类的运算 (20分)

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)

#include 
using namespace std;
class Complex
{
     
	public:
		Complex(double r=0, double i=0):real(r), imag(i){
     	}
		Complex operator+(Complex c) const;//重载双目运算符'+'
		Complex operator-=(Complex c); //重载双目运算符'-='
		friend Complex operator-(Complex c1,Complex c2) ;//重载双目运算符'-'
		void Display() const;
	private:
		double real;
		double imag;
};
Complex Complex::operator+ (Complex c)const{
     
c.imag=c.imag+this->imag;
c.real=c.real+this->real;
return c;
}
Complex Complex::operator-=(Complex c){
     
this->imag=this->imag-c.imag;
this->real=this->real-c.real;
return *this;

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

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;
}

• 这个题目的重点是要区分-=和-
  -=：c-=b相当于c=c-b 但是在这里他与普通的-不同的是左操作数所指的是this指针所指的对象，而右操作数才是传过来的参数 因此，这里是this->imag=this->imag-c.imag; this->real=this->real-c.real;
  特别注意的是最后返回的也是this指针所指的对象return *this;
• 其次要注意friend Complex operator-(Complex c1,Complex c2)是一个友元函数，他不在这个类内，所以不需要加类名