1 #include<iostream>
 2 using namespace std;
 3 class Complex
 4 {
 5 public:
 6     Complex(double r=0.0,double i=0.0);
 7     void print();
//friend为友元函数的关键字,这两个符号运算符重载函数的参数类型至少有一个类类型或者类的引用
 8     friend Complex operator+(Complex &a,Complex &b);
 9     friend Complex operator-(Complex &a,Complex &b);
10 private:
11     double real;
12     double imag;
13 };
14 Complex::Complex(double r,double i) //在类外定义函数,需要用::作用域符号
15 {
16     real = r;
17     imag = i;
18 }
19 Complex operator+(Complex &a,Complex &b)
20 {
21     Complex temp; //创建一个临时对象
22     temp.real = a.real + b.real;
23     temp.imag = a.imag + b.imag;
24     return temp; 
25 }
26 Complex operator-(Complex &a,Complex &b)
27 {
28     Complex temp; //创建一个临时对象
29     temp.real = a.real - b.real;
30     temp.imag = a.imag - b.imag;
31     return temp;
32 }
33 void Complex::print()
34 {
35     cout<<real;
36     if(imag>0) cout<<"+";
37     if(imag!=0) cout<<imag<<'i'<<endl;
38 }
39 int main(int agrs,const char *agrv[])
40 {
41     Complex A1(2.3,4.6),A2(3.6,2.8),A3,A4;
42     A3 = A1 + A2;//A3 = operator+(A1,A2);     //对运算符重载函数的调用，前面的为隐式调用，后面的为显示调用
43     A4 = A1 - A2;//A4 = operator-(A1-A2);
44     A1.print();
45     A2.print();
46     A3.print();
47     A4.print();
48     
49     return 0;
50 }

2.3+4.6i
3.6+2.8i
5.9+7.4i
-1.3+1.8i
Program ended with exit code: 0