写一个C++程序要求包括（1）类的定义，构造函数，成员函数 （2）．两个复数运算的运算符重载.重载 +、-、*、/、++、--、<<、>>等运算符 （3） double型数可以转换成复数

好的，以下是一个完整的 C++ 程序，满足您的要求：

#include <iostream>
using namespace std;

class Complex {
private:
    double real; // 实部
    double imag; // 虚部
public:
    Complex() { // 默认构造函数
        real = 0;
        imag = 0;
    }
    Complex(double r, double i) { // 带参数构造函数
        real = r;
        imag = i;
    }
    Complex(const Complex& c) { // 拷贝构造函数
        real = c.real;
        imag = c.imag;
    }
    ~Complex() { // 析构函数
        // do nothing
    }
    void setReal(double r) { // 设置实部
        real = r;
    }
    void setImag(double i) { // 设置虚部
        imag = i;
    }
    double getReal() const { // 获取实部
        return real;
    }
    double getImag() const { // 获取虚部
        return imag;
    }
    Complex operator+(const Complex& c) const { // 运算符重载 +
        return Complex(real + c.real, imag + c.imag);
    }
    Complex operator-(const Complex& c) const { // 运算符重载 -
        return Complex(real - c.real, imag - c.imag);
    }
    Complex operator*(const Complex& c) const { // 运算符重载 *
        return Complex(real * c.real - imag * c.imag, real * c.imag + imag * c.real);
    }
    Complex operator/(const Complex& c) const { // 运算符重载 /
        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);
    }
    Complex operator++() { // 运算符重载前置 ++
        real++;
        imag++;
        return *this;
    }
    Complex operator++(int) { // 运算符重载后置 ++
        Complex tmp(*this);
        real++;
        imag++;
        return tmp;
    }
    Complex operator--() { // 运算符重载前置 --
        real--;
        imag--;
        return *this;
    }
    Complex operator--(int) { // 运算符重载后置 --
        Complex tmp(*this);
        real--;
        imag--;
        return tmp;
    }
    friend istream& operator>>(istream& is, Complex& c) { // 运算符重载 >>
        is >> c.real >> c.imag;
        return is;
    }
    friend ostream& operator<<(ostream& os, const Complex& c) { // 运算符重载 <<
        os << c.real << " + " << c.imag << "i";
        return os;
    }
    explicit operator double() const { // 类型转换函数
        return real;
    }
};

int main() {
    Complex c1(1.0, 2.0);
    Complex c2(3.0, 4.0);

    // 运算符重载
    Complex c3 = c1 + c2;
    Complex c4 = c1 - c2;
    Complex c5 = c1 * c2;
    Complex c6 = c1 / c2;
    Complex c7 = ++c1;
    Complex c8 = c2++;
    Complex c9 = --c1;
    Complex c10 = c2--;
    cout << "c1 = " << c1 << endl;
    cout << "c2 = " << c2 << endl;
    cout << "c1 + c2 = " << c3 << endl;
    cout << "c1 - c2 = " << c4 << endl;
    cout << "c1 * c2 = " << c5 << endl;
    cout << "c1 / c2 = " << c6 << endl;
    cout << "++c1 = " << c7 << endl;
    cout << "c2++ = " << c8 << endl;
    cout << "--c1 = " << c9 << endl;
    cout << "c2-- = " << c10 << endl;

    // 类型转换
    double d = (double)c1;
    cout << "double(c1) = " << d << endl;

    return 0;
}

程序中定义了一个 `Complex` 类，实现了复数的加、减、乘、除、前置/后置自增/自减、输入输出运算符重载以及类型转换。在 `main` 函数中进行了测试。