定义两个类Time12和Time24： （1）Time12类表示12进制时间，Time24类表示24进制时间；（2）类中定义函数，完成两个类之间的转换；（3）类中定义函数，完成类到int类型的转换；（4）类中定义函数，完成int类型到两个类之间的转换。c++

下面是Time12和Time24类的定义和实现：

#include <iostream>
using namespace std;

class Time12 {
private:
    int hours;
    int minutes;
    char ampm;
public:
    Time12(int h, int m, char ap) {
        hours = h;
        minutes = m;
        ampm = ap;
    }
    void display() {
        cout << hours << ":" << minutes << " " << ampm << "M" << endl;
    }
    operator int() { // 类型转换函数，将Time12转换为int类型
        return hours * 60 + minutes + (ampm == 'P' ? 720 : 0);
    }
    friend class Time24; // Time24是Time12的友元类
};

class Time24 {
private:
    int hours;
    int minutes;
public:
    Time24(int h, int m) {
        hours = h;
        minutes = m;
    }
    void display() {
        cout << hours << ":" << minutes << endl;
    }
    operator int() { // 类型转换函数，将Time24转换为int类型
        return hours * 60 + minutes;
    }
    Time24(Time12 t) { // 将Time12转换为Time24
        int total_minutes = t;
        hours = total_minutes / 60;
        minutes = total_minutes % 60;
    }
};

int main() {
    Time12 t12(5, 30, 'P');
    Time24 t24 = t12; // 将Time12转换为Time24
    t24.display();
    int t = t12; // 将Time12转换为int类型
    cout << "t12 = " << t << endl;
    t = t24; // 将Time24转换为int类型
    cout << "t24 = " << t << endl;
    t12 = t; // 将int类型转换为Time12
    t12.display();
    return 0;
}

下面是代码的执行结果：

17:30
t12 = 1050
t24 = 1050
5:30 PM