用c++定义Festival类作为基类,包含属性Name,行为Add,Del,查找指定名字的节日是否存在,定义派生类DateFestival类,新增属性和行为:Date,修改日期.定义派生类WeekDayFestival类,新增属性和行为:节日是几月的第几个星期几,可进行修改

好的，下面是用C++定义的Festival类作为基类的示例代码：

#include <iostream>
#include <string>

class Festival {
protected:
    std::string Name;

public:
    void Add() {
        std::cout << "Festival added." << std::endl;
    }

    void Del() {
        std::cout << "Festival deleted." << std::endl;
    }

    bool Find(const std::string& name) {
        if (Name == name) {
            std::cout << "Festival found." << std::endl;
            return true;
        }

        std::cout << "Festival not found." << std::endl;
        return false;
    }
};

class DateFestival : public Festival {
private:
    std::string Date;

public:
    void ModifyDate(const std::string& newDate) {
        Date = newDate;
        std::cout << "Date modified: " << Date << std::endl;
    }
};

class WeekDayFestival : public Festival {
private:
    std::string WeekDay;

public:
    void SetWeekDay(const std::string& weekDay) {
        WeekDay = weekDay;
        std::cout << "Week day set: " << WeekDay << std::endl;
    }

    void ModifyWeekDay(const std::string& newWeekDay) {
        WeekDay = newWeekDay;
        std::cout << "Week day modified: " << WeekDay << std::endl;
    }
};

int main() {
    // Example usage
    DateFestival dateFestival;
    dateFestival.Add();
    dateFestival.Find("New Year");  // Festival not found.
    dateFestival.ModifyDate("January 1st");

    WeekDayFestival weekDayFestival;
    weekDayFestival.Add();
    weekDayFestival.SetWeekDay("Sunday");
    weekDayFestival.Find("Christmas");  // Festival not found.
    weekDayFestival.ModifyWeekDay("Friday");

    return 0;
}

这个示例代码定义了一个基类`Festival`，它包含一个属性`Name`和三个行为：`Add()`、`Del()`和`Find()`。然后派生了两个类`DateFestival`和`WeekDayFestival`，分别新增了属性和行为。

`DateFestival`类新增了一个属性`Date`，并添加了一个行为`ModifyDate()`用于修改日期。

`WeekDayFestival`类新增了一个属性`WeekDay`，并添加了两个行为`SetWeekDay()`用于设置星期几，并且`ModifyWeekDay()`用于修改星期几。

在主函数中，我们可以看到对这些类的使用示例。你可以根据需要进行修改和补充。