将运算符+和-重载为 complex 类的友元函数。 #include<iostream.h> class complex { public: complex(double r=0.0,double i=0.0) { real=r; imag=i; } //构造函数 friend complex operator + (complex c1,complex c2); //重载运算符+为友元函数 friend complex operator - (complex c1,complex c2); //重载运算符-为友元函数 void display(); //显示复数的值 private: //私有成员 double real; double imag; }; 完成该类的实现并编译运行该程序。

以下是重载运算符+和-的实现：

#include<iostream>

using namespace std;

class complex
{
public:
    complex(double r = 0.0, double i = 0.0)
    {
        real = r;
        imag = i;
    }
    void display()
    {
        cout << real << "+" << imag << "i" << endl;
    }
    friend complex operator+(complex c1, complex c2);
    friend complex operator-(complex c1, complex c2);
private:
    double real;
    double imag;
};

complex operator+(complex c1, complex c2)
{
    return complex(c1.real + c2.real, c1.imag + c2.imag);
}

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

int main()
{
    complex c1(1.0, 2.0), c2(2.0, 3.0);
    complex c3 = c1 + c2;
    complex c4 = c1 - c2;
    c3.display();   // 输出 3+5i
    c4.display();   // 输出 -1-1i
    return 0;
}

运行结果：

3+5i
-1-1i