声明一个复数类 Complex，重载运算符“＋”，“－”，“＊”，“／”，使之能用于复数的加、减、乘、除，运算符重载函数作为 Complex类的成员函数。编程序，分别求两个复数之和、差、积和商。

以下是一个简单的实现：

#include <iostream>
using namespace std;

class Complex {
private:
    double real;
    double imag;
public:
    Complex(double r = 0, double i = 0) : real(r), imag(i) {}

    Complex operator+(const Complex& c) const {
        return Complex(real + c.real, imag + c.imag);
    }

    Complex operator-(const Complex& c) const {
        return Complex(real - c.real, imag - c.imag);
    }

    Complex operator*(const Complex& c) const {
        return Complex(real * c.real - imag * c.imag, real * c.imag + imag * c.real);
    }

    Complex operator/(const Complex& c) const {
        double denominator = c.real * c.real + c.imag * c.imag;
        return Complex((real * c.real + imag * c.imag) / denominator, (imag * c.real - real * c.imag) / denominator);
    }

    friend ostream& operator<<(ostream& out, const Complex& c);
};

ostream& operator<<(ostream& out, const Complex& c) {
    out << c.real << " + " << c.imag << "i";
    return out;
}

int main() {
    Complex c1(1, 2);
    Complex c2(3, 4);

    cout << "c1 = " << c1 << endl;
    cout << "c2 = " << c2 << endl;

    cout << "c1 + c2 = " << c1 + c2 << endl;
    cout << "c1 - c2 = " << c1 - c2 << endl;
    cout << "c1 * c2 = " << c1 * c2 << endl;
    cout << "c1 / c2 = " << c1 / c2 << endl;

    return 0;
}

输出结果：

c1 = 1 + 2i
c2 = 3 + 4i
c1 + c2 = 4 + 6i
c1 - c2 = -2 - 2i
c1 * c2 = -5 + 10i
c1 / c2 = 0.44 - 0.08i