Visual C ++无法将我的函数识别为类的一部分

如何解决Visual C ++无法将我的函数识别为类的一部分

我正在制作一个不错的程序，该程序可以有任何日期，并可以找到它的前一天和后一天。我已经完成了所有工作，除了调试时，我遇到了13个错误！阅读错误语句后，我发现该函数未被识别为类的一部分，但我不知道为什么。

我觉得自己了解自己在做什么，但是有些不对劲。如果有人有任何建议，请告诉我。谢谢！

我有三个文件：

主文件（Source.cpp）：

#include <iostream>
#include <iomanip>
#include <string>
#include "DateType.h"



using namespace std;
int main() {
    //Inputs
    int month,day,year;
    bool flag;
    DateType today,tomorrow,yesterday;
    do { //Registers input and checks if it can go through program
        cout << "Enter the current month (1-12): ";
        cin >> month;
        cout << "Enter the current year: ";
        cin >> year;
        cout << "Enter in today's date: ";
        cin >> day;
        today.SetDate(month,year);
        flag = today.valid_date();
    } while (!flag);

    //Equalizing all three objects
    tomorrow = today;
    yesterday = today;
    //Moving ford and back one day
    tomorrow.NextDay();
    yesterday.PreviousDay();

    //Output
    cout << "Given Date: " << today.print_Day() << endl;
    cout << "Next Date: " << tomorrow.print_Day() << endl;
    cout << "Previous Date: " << yesterday.print_Day() << endl;









    system("pause");
    return 0;
}

头文件（DateType.h）

#pragma once
#include <iostream>
#include <iomanip>
#include <string>

enum months { Jan=31,Feb = 28,March = 31,April = 30,May = 31,June = 30,July = 31,August = 31,Sept = 30,Oct = 31,Nov = 30,Dec = 31,Feb_Leap = 29 };

class DateType {
private:
    int mo;
    int day;
    int yr;
    months DaysInMonth;
    void Day_Month_Assign(); //This function does the same thing as DaysinMonth() on the assignment sheet,using the enum
public:
    DateType(); //Constructor to set mo=0,day=0,yr=1000
    void SetDate(int,int,int); //Date is set according to the incoming parameter
    void NextDay(); //Date is increased by one to get NextDay
    void PreviousDay(); //Date is decreased by one day to get Previous Day
    string print_Day(); //Returns a string value
    bool valid_date(); //Checks if an input is a valid date
};

DateType.cpp文件

#include <iostream>
#include <cstdlib>
#include "DateType.h"
#include <string>

using namespace std;

DateType::DateType() {
    mo = 0;
    day = 0;
    yr = 1000;
}

void DateType::Day_Month_Assign() {
    switch (mo) {
    case 1: DaysInMonth = Jan;
    case 2: DaysInMonth = Feb;
    case 3: DaysInMonth = March;
    case 4: DaysInMonth = April;
    case 5: DaysInMonth = May;
    case 6: DaysInMonth = June;
    case 7: DaysInMonth = July;
    case 8: DaysInMonth = August;
    case 9: DaysInMonth = Sept;
    case 10: DaysInMonth = Oct;
    case 11: DaysInMonth = Nov;
    case 12: DaysInMonth = Dec;
    }
    if ((yr % 4 == 0 && yr % 100 != 0) ||
        (yr % 400 == 0))
        DaysInMonth = Feb_Leap;
}

void DateType::SetDate(int month,int days,int year) {
    mo = month;
    day = days;
    yr = year;
    Day_Month_Assign();
}

void DateType::NextDay() {
    day++;
    if (day > DaysInMonth) { //Raises month
        day = 1;
        mo++;
        Day_Month_Assign(); //Assigns new value to enum
    }
    if (mo > 12) {
        mo = 1;
        yr++;
        Day_Month_Assign();
    }
}

void DateType::PreviousDay() {
    day--;
    //Different order than the last one
    //I need to get the days in month from enum first 
    //That will be the new day value
    if (day == 0) {
        mo--;
        Day_Month_Assign();
        day = DaysInMonth;
    }
    if (mo == 0) {
        yr--;
        mo = 12;
        Day_Month_Assign();
        day = DaysInMonth;
    }
}

string DateType::print_Day() {
    string date;
    date = (to_string(mo) + "-" + to_string(day) + "-" + to_string(yr));
    return date;
}

bool DateType::valid_date() {
    bool flag;
    if (day <= DaysInMonth && day >= 1) { //Days in Month Check
        if (mo > 0 && mo <= 12) { //Month in Year Check
            flag = true;
            cout << "Valid Date,Accepted!\n";
        }
        else {
            flag = false;
            cout << "Invalid Month!\n";
        }
    }
    else {
        flag = false;
        cout << "Invalid Date!\n";
    }
    return flag;
}

编辑：所讨论的函数是String DateType::print_Day()函数。错误如下：

主文件：

'print_Day' is not a member of 'DateType' (Called 3 Times),C2039

CPP文件：

'print_Day' is not a member of 'DateType' (Line 73,C2039)

'mo': undeclared identifier (Line 75,C2065)

'day': undeclared identifier (Line 75,C2065)

'yr': undeclared identifier (Line 75,C2065)

declaration is incompatible with " DateType::print_Day()" (declared at line 21 of Header File) (Line 73,E0147)

头文件：

'print_Day': unknown override specifier (Line 21,C3646)

syntax error: '(' (Line 21,C2059)

unexpected token(s) preceding ';' (Line 21,C2238)

这三个头文件的所有错误稍后在错误列表中再次引发。我希望这会有所帮助！

解决方法

在DateType.h中，字符串未知，因为字符串类属于std名称空间。要解决该错误，请将print_Day的定义更改为

std::string print_Day()

请勿尝试通过在页眉中添加using namespace std;来解决此问题，因为这样做不会导致问题继续下去。

关于编程风格的小注释：在DateType.cpp中，最好先包含DateType.h。这样，您将知道DateType.h没有依赖项，并且可以包含在任何cpp文件中。

,

这没有解决问题，但没有命名变量flag。给变量名称告诉您它们的作用。在这种情况下，date_is_valid尽管有点长，但更加清晰。但是您不需要它。只需进行循环测试while(!today.valid_date())。