简单的C ++计算一周中的几天，有点卡住？

Question

所以这就是我想要实现的目标

这是我的代码。我现在完全陷入困境，我在这里错过了什么，就在我面前？我觉得我已经完成了所有功能，但我认为它不会正确计算它。我在这里有一些错误，我无法修复甚至尝试运行它。 谢谢你的帮助; -

#include <iostream>
#include <cmath>
#include <string>

using namespace std;

class dayType
{
public:
    void setDay(int dayNum);
    // set the day with the dayNum as parameter
    void printd(dayNum);
    // print the dayNum
    int returnDay();
    // return the day of the week
    void dayAfter();
    // return next day
    void dayBefore();
    // return previous day
    void randomDay(int dayNum);
    // function to return a day after a certain number of days


    dayType(int dayNum);
    // Constructor with parameters setting dayNum according to parameters
    dayType();
    //Default constructor

    private:
        int today;
        int yest;
        int tom;
        int dayN;

    };




    void dayType::printd(int dayNum)
    {
        if (dayNum == 1)
            cout << "Monday" << endl;

        if (dayNum == 2)
            cout << "Tuesday" << endl;

        if (dayNum == 3)
            cout << "Wednesday" << endl;

        if (dayNum == 4)
            cout << "Thursday" << endl;

        if (dayNum == 5)
            cout << "Friday" << endl;

        if (dayNum == 6)
            cout << "Saturday" << endl;

        if (dayNum == 7)
            cout << "Sunday" << endl;

    }


    void dayType::setDay(int dayNum)
    {
    today = dayNum;

    };

    int dayType::returnDay()
    {
        return today;

    };

    void dayType::printd(<#int dayNum#>);
    {
    cout << "The current day is: " << today << endl;
    }


    void dayType::dayBefore()
    {
        if(today == 0)
            yest = 6;
        else today--;
    };


    void dayType::dayAfter()
    {
        if(today == 6)
        tom = 0;

    };

    void dayType::randomDay(int dayNum)
    {
        dayN=(today+dayNum);
        today =(dayN%7);

    };

    dayType::dayType()
    {
        today = 0;
    }


    dayType::dayType(int daynum)
    {
    today = daynum;
    }
    // do I need these constructors here doing this?



            int main()

            {
                int dayWeek;

                cout << "Please enter a number for the day of the week: " << endl;
                cout << "1 - Monday" << endl;
                cout << "2 - Tuesday" << endl;
                cout << "3 - Wednesday" << endl;
                cout << "4 - Thursday" << endl;
                cout << "5 - Friday" << endl;
                cout << "6 - Saturday" << endl;
                cout << "7 - Sunday" << endl;

                while (dayWeek<= 7)

                    cin >> dayWeek;

                dayType thisDay;

                cout << "Today is: ";
                thisDay.returnDay();
                thisDay.printd(int dayNum);


                cout << "Yesterday was: ";
                thisDay.dayBefore();
                thisDay.printd(int dayNum);


                cout << "Tomorrow is: ";
                thisDay.dayAfter();
                thisDay.printd(int dayNum);

                cout << "Type a number of days from today and it will be: ";
                thisDay.randomDay(dayNum);

                return 0;
            };
        }

Answer 1

您的代码应该更像这样：

#include <iostream>
#include <cmath>
#include <string>

using namespace std;

class dayType
{
public:
    void setDay(int dayNum);
    void printd();
    // set the day with the dayNum as parameter
    void printd(int dayNum);
    // print the dayNum
    int returnDay();
    // return the day of the week
    int dayAfter();
    // return next day
    int dayBefore();
    // return previous day
    int randomDay(int dayNum);
    // function to return a day after a certain number of days


    dayType(int dayNum);
    // Constructor with parameters setting dayNum according to parameters
    dayType();
    //Default constructor

    private:
        int today;

};




void dayType::printd(int dayNum)
{
    if (dayNum == 1)
        cout << "Monday" << endl;

    if (dayNum == 2)
        cout << "Tuesday" << endl;

    if (dayNum == 3)
        cout << "Wednesday" << endl;

    if (dayNum == 4)
        cout << "Thursday" << endl;

    if (dayNum == 5)
        cout << "Friday" << endl;

    if (dayNum == 6)
        cout << "Saturday" << endl;

    if (dayNum == 7)
        cout << "Sunday" << endl;

}


void dayType::setDay(int dayNum)
{
    today = dayNum;

}

int dayType::returnDay()
{
   return today;

}

void dayType::printd()
{
cout << "The current day is: " << today << endl;
}


int dayType::dayBefore()
{
    int yest;
    if(today == 0)
        yest = 6;
    else
        yest = today - 1;
    return yest;
};


int dayType::dayAfter()
{
    int tom;

    if(today == 6)
        tom = 0;
    else 
        tom = today + 1;
    return tom;

};

int dayType::randomDay(int dayNum)
{
    int dayN = (today+dayNum);
    return (dayN % 7)

};

dayType::dayType()
{
    today = 0;
}


dayType::dayType(int daynum)
{
    today = daynum;
}
// do I need these constructors here doing this?



int main()

{
    int dayWeek = -1;
    int random = -1;

    cout << "Please enter a number for the day of the week: " << endl;
    cout << "1 - Monday" << endl;
    cout << "2 - Tuesday" << endl;
    cout << "3 - Wednesday" << endl;
    cout << "4 - Thursday" << endl;
    cout << "5 - Friday" << endl;
    cout << "6 - Saturday" << endl;
    cout << "7 - Sunday" << endl;

    while (dayWeek >= 7 || dayWeek < 0)

        cin >> dayWeek;

    dayType thisDay;
    thisDay.today = dayWeek;

    thisDay.printd();


    cout << "Yesterday was: ";
    thisDay.printd(thisDay.dayBefore());


    cout << "Tomorrow is: ";
    thisDay.printd(thisDay.dayAfter());

    cout << "Type a number of days : ";

    while (random < 0)

        cin >> random;

    cout << "Now we are  ";
    thisDay.printd(thisDay.randomDay(random));

    return 0;
}

当你调用这样的函数：void fonction(int a, int b)时，你可以这样调用它：fonction(1, 2);。您不必编写参数的类型。在您的课程中，仅声明您的功能所需的值。在之前的代码中，您声明了tom，yes和dayN，但您无需保留其值。

我没有测试代码，所以如果你有错误，请写下来，我会编辑这篇文章。

Answer 2

就我个人而言，我建议您使用enum而不是int来跟踪当天，以及必要的操作员，让您可以循环使用这些日子。这样您就可以更轻松地定义dayType并与之互动，轻松修复您遇到的错误。

#include <iostream>
#include <cmath>
#include <string>
#include <limits>

using namespace std;

class dayType
{
public:
    // Days enum:
    enum Days {
        D_MONDAY = 1,
        D_TUESDAY,
        D_WEDNESDAY,
        D_THURSDAY,
        D_FRIDAY,
        D_SATURDAY,
        D_SUNDAY
    };

    void setDay(int dayNum);
    // set the day with the dayNum as parameter

    void printd(int dayNum);
    // print the dayNum
    void printd();
    // Prints the current day.

    Days returnDay();
    // return the day of the week
    Days dayAfter();
    // return next day
    Days dayBefore();
    // return previous day
    Days randomDay(int dayNum);
    // function to return a day after a certain number of days


    dayType(int dayNum);
    // Constructor with parameters setting dayNum according to parameters
    dayType();
    //Default constructor

private:
    Days today;
};

// Compound assignment addition:
dayType::Days& operator+=(dayType::Days& left, int right)
{
    typedef dayType::Days Days;

    int temp = static_cast<int>(left) + right;

    // In case of adding negative numbers.
    while (temp < dayType::D_MONDAY)
        temp += dayType::D_SUNDAY;

    while (temp > dayType::D_SUNDAY)
        temp -= dayType::D_SUNDAY;

    left = static_cast<Days>(temp);

    return left;
}

// Compound assignment subtraction:
dayType::Days& operator-=(dayType::Days& left, int right)
{
    typedef dayType::Days Days;

    int temp = static_cast<int>(left) - right;

    while (temp < dayType::D_MONDAY)
        temp += dayType::D_SUNDAY;

    // In case of subtracting negative numbers.
    while (temp > dayType::D_SUNDAY)
        temp -= dayType::D_SUNDAY;

    left = static_cast<Days>(temp);

    return left;
}


// Addition.  Uses compound assignment addition internally.
dayType::Days  operator+(dayType::Days left, int right)
{
    return left += right;
}

// Subtraction.  Uses compound assignment subtraction internally.
dayType::Days  operator-(dayType::Days left, int right)
{
    return left -= right;
}


// Prefix increment (++day):
dayType::Days  operator++(dayType::Days& day)
{
    return day += 1;
}

// Postfix increment (day++):
dayType::Days  operator++(dayType::Days& day, int)
{
    typedef dayType::Days Days;

    Days temp = day;
    ++day;
    return temp;
}


// Prefix decrement (--day):
dayType::Days  operator--(dayType::Days& day)
{
    return day -= 1;
}

// Postfix decrement (day--):
dayType::Days  operator--(dayType::Days& day, int)
{
    typedef dayType::Days Days;

    Days temp = day;
    --day;
    return temp;
}


void dayType::printd(int dayNum)
{
    if (dayNum == D_MONDAY)
        cout << "Monday" << endl;

    if (dayNum == D_TUESDAY)
        cout << "Tuesday" << endl;

    if (dayNum == D_WEDNESDAY)
        cout << "Wednesday" << endl;

    if (dayNum == D_THURSDAY)
        cout << "Thursday" << endl;

    if (dayNum == D_FRIDAY)
        cout << "Friday" << endl;

    if (dayNum == D_SATURDAY)
        cout << "Saturday" << endl;

    if (dayNum == D_SUNDAY)
        cout << "Sunday" << endl;
}

void dayType::printd()
{
    cout << "The current day is: ";
    printd(today);
}


void dayType::setDay(int dayNum)
{
    today = static_cast<Days>(dayNum);
};

dayType::Days dayType::returnDay()
{
    return today;
};

dayType::Days dayType::dayBefore()
{
    return today - 1;
};


dayType::Days dayType::dayAfter()
{
    return today + 1;
};

dayType::Days dayType::randomDay(int dayNum)
{
    return today + dayNum;
};

dayType::dayType()
{
    today = D_SUNDAY;
}


dayType::dayType(int daynum)
{
    today = static_cast<Days>(daynum);
}



int main()
{
    int dayWeek = 0;

    cout << "Please enter a number for the day of the week: " << endl;
    cout << "1 - Monday" << endl;
    cout << "2 - Tuesday" << endl;
    cout << "3 - Wednesday" << endl;
    cout << "4 - Thursday" << endl;
    cout << "5 - Friday" << endl;
    cout << "6 - Saturday" << endl;
    cout << "7 - Sunday" << endl;

    while (!((dayWeek > 0) && (dayWeek < 8)))
        cin >> dayWeek;

    dayType thisDay(dayWeek);

    // -----

    cout << "Today is: ";
    thisDay.printd(thisDay.returnDay());

    // -----

    cout << "Yesterday was: ";
    thisDay.printd(thisDay.dayBefore());

    // -----

    cout << "Tomorrow is: ";
    thisDay.printd(thisDay.dayAfter());

    // -----

    cout << "Type a number of days: ";

    int random;
    cin >> random;
    cin.ignore(std::numeric_limits<streamsize>::max(), '\n');

    cout << "In " << random << " days, it will be: ";
    thisDay.printd(thisDay.randomDay(random));
};

目前，这应该适用于您想要的内容，但需要注意的是，如果您想将int用作Days（例如在{{中初始化today 1}}），你必须明确地把它变成一个。 （相反，dayType::dayType(int daynum)可以隐含地用作Days，通过将int的返回值传递给dayType::returnDay()或者传递dayType::printd()来证明} Days。）

如果您想在cout之外使用Days，可以将其用作dayType（例如在运算符＆＃39;返回类型中）。您还可以使用dayType::Days将其带入当前范围，从而可以将其简化为typedef dayType::Days Days;（例如Days或dayType::Days operator++(dayType::Days& day, int)）。同样，要使用枚举值本身，请在其名称前加上dayType::Days operator--(dayType::Days& day, int)。

当你正在使用这个练习和你的问题时，作为一个学习机会，我留下了一些可以改进的地方。它目前工作正常，但有进行修改的空间，可以使其更好地工作。