1 返回类型 operator运算符号(形式参数列表)
2 {
3 函数体
4 }

1 #include <iostream>
2 using namespace std;
3 class complex //复数类
4 {
5 public:
6 complex(double r=0.0,double i=0.0)//构造函数
{real=r; imag=i;
}
7 complex operator +(complex &c2); //重载+运算符
8 complex operator -(complex &c2); //重载-运算符
9 void display()
10 {
11 cout<<real<<"+"<<imag<<"i"<<endl;
12 }
13 private:
14 double real; //实部
15 double imag; //虚部
16 };

complex complex::operator +(complex &c2)
18 { complex c;
20 c.real=c2.real+real;
21 c.imag=c2.imag+imag;
22 return c;
23 }
24 complex complex::operator -(complex &c2)
25 { complex c;
27 c.real=real-c2.real; //顺序不能颠倒
28 c.imag=imag-c2.imag;
29 return c;
30 }
31 int main()
32 { complex c1(1,2),c2(3,4),c3;
34 c3=c2+c1; c3.display(); //输出4+6i
36 c3=c2-c1; c3.display(); //输出2+2i
38 return 0;
39 }

1 #include <iostream>
2 using namespace std;
3 class complex //复数类
4 {
5 public:
6 complex(double r=0.0,double i=0.0) {real=r; imag=i;}//构造函数
7 friend complex operator +(const complex &c1,const complex &c2);
//重载+运算符
8 friend complex operator -(const complex &c1,const complex &c2);
//重载-运算符
9 void display()
10 { cout<<real<<"+"<<imag<<"i"<<endl; }
11 private:
12 double real; //实部
13 double imag; //虚部
14 };
15 complex operator +(const complex &c1,const complex &c2)
16 { complex c3;
17 c3.real=c1.real+c2.real;
18 c3.imag=c1.imag+c2.imag;
19 return c3;
20 }
21 complex operator -(const complex &c1,const complex &c2)
22 { complex c3;
23 c3.real=c1.real-c2.real;
24 c3.imag=c1.imag-c2.imag;
25 return c3;
26 }
27 int main()
28 { complex c1(1,2),c2(3,4),c3;
29 c3=c2+c1; c3.display(); //输出4+6i
30 c3=c2-c1; c3.display(); //输出2+2i
31 return 0;
32 }