Question

 #include <iostream>
 #include <string>


 class Date
 {
   public:
    Date(int, int, int);
    Date(std::string, int, int);
    void print();
    void printFullDate();
    int getMonth();
    int getDay();
    int getYear();
    void setMonth(int);
    void setDay(int);
    void setYear(int);


    private:
    int mm,dd,yy;
    std::string mstr;

 };

这是我的类Date

的头文件

以下是实施

#include <iostream>
#include "Date.h"

using namespace std;

Date::Date(int mm, int dd, int yy)
{
    if(mm < 1 || mm > 12 )
     {
        cout << "Please Enter a Valid Month (1-12)";
        cin >> mm;
     }

    if(mm == 1 || mm == 3 || mm == 5 || mm == 7 || mm == 8 || mm == 10 || mm == 12)
        {
            if(dd < 1 || dd > 31)
            {
                cout << "Please Enter a Valid Date For the Month Entered(1-31)";
                cin >> dd;
            }
        }

    if(mm == 4 || mm == 6 || mm == 9 || mm == 11)
    {
        if(dd < 1 || dd >30)
        {
            cout << "Please Enter a Valid Date for the Month Entered(1-30)";
            cin >> dd;
        }
    }

    if ( (yy % 4 == 0 && yy % 100 != 0) || ( yy % 400 == 0))
    {
        if(mm == 2)
        {
            if( dd < 1 || dd > 29)
            {
                cout << "Please Enter a Valid Date for the Month Entered(1-29)";
                cin >> dd;
            }
        }


    }
    else 
    {
        if(mm == 2)
        {
            if(dd < 1 || dd > 28)
            {
                cout << "Please Enter a Valid Date for the Month Entered(1-28)";
                cin >> dd;
            }
        }
    }   

    if (yy < 1)
    {
        cout << "Please Enter a Valid Date of the era AD";
        cin >> yy;
    }

    switch(mm) 
    {
        case 1:
        mstr = "January";
        break;

        case 2:
        mstr = "February";
        break;

        case 3:
        mstr = "March";
        break;

        case 4:
        mstr = "April";
        break;

        case 5:
        mstr = "May";
        break;

        case 6:
        mstr = "June";
        break;

        case 7:
        mstr = "July";
        break;

        case 8:
        mstr = "August";
        break;

        case 9:
        mstr = "September";
        break;

        case 10:
        mstr = "October";
        break;

        case 11:
        mstr = "November";
        break;

        case 12:    
        mstr = "December";
        break;

    }


}

Date::Date(string mstr, int dd, int yy)
{

}

void Date::print()
{
    cout << "MM/DD/YYYY: " << mm << "/" << dd << "/" << yy << endl;
}

void Date::printFullDate()
{
    cout << "Month DD, YYYY: " << mstr << " " << dd << ", " << yy << endl;
    cout << "**********" << endl << endl;
}

void Date::setDay(int day)
{
    dd = day;
}

void Date::setMonth(int month)
{
    mm = month;
}

void Date::setYear(int year)
{
    yy = year;
}

int Date::getDay()
{
    return dd;
}

int Date::getMonth()
{
    return mm;
}

int Date::getYear()
{
    return yy;
}

当我调用函数Date（int，int，int）时，它会很好地运行。但是，当我调用print函数时，变量不会保留构造函数中指定的值。当构造函数更正一个月，一天或一年时，该数据不会在打印时输出。而是输出原始未更改的值。我相信一旦传递给构造函数的变量应该对整个类保持不变。我搞不清楚了。任何帮助将不胜感激。

Answer 1

那是因为你的构造函数的参数......

Date::Date(int mm, int dd, int yy)

...是具有相同名称的类成员变量的不同变量。我通常将成员命名为尾随下划线，例如mm_, dd_, yy_ - 然后在构造函数的末尾，您可以像...一样分配给它们

mm_ = mm; dd_ = dd; yy_ = yy; mstr_ = mstr;

重载构造函数和变量传递的麻烦

1 个答案: