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c++ - 将解析的数据输入结构时遇到问题

问题描述

我正在学习 C++ 课程，在这个项目中我遇到了障碍。我应该以 MM/DD/YYYY 的形式接受用户的输入，然后使用结构以几种方式对其进行操作。我尝试了几种不同的方法来分配结构中的变量，但我永远无法让它们代表任何值

我试过 getline(cin, data); 以及获取（）；

#include <iostream>
#include <fstream>
#include <istream>
#include <string>
#include <stdlib.h>
#include <stdio.h>
using namespace std;

struct date
{
    string day;
    string month;
    string year;
} pinfo;
string RunAgain;
int main()
{
    struct date user;
    while (1)
    {
        string user_entry;
        cout << "Please enter date in the form of MM/DD/YYYY ";
        getline(cin, user_entry);


        string str = user_entry;

        // month is from position 0, to until first / found
        pinfo.month = str.substr(0, str.find("/", 0));
        str = str.substr(str.find("/", 0) + 1, str.length()); // new string
        user.month = pinfo.month;


        // dsy is from position 0 to until first / found
        pinfo.day = str.substr(0, str.find("/", 0));
        str = str.substr(str.find("/", 0) + 1, str.length()); // new string
        user.day = pinfo.day;

        //  Year is from position 0, to until "\n" found
        pinfo.year = str.substr(0, str.find("\n", 0));
        str = str.substr(str.find("\n", 0) + 1, str.length()); // new str                                                                       
        user.year = pinfo.year;


        string month_alpha;

        // error check user entry 
        if (user.month > "12" || user.month < "1")
        {
            cout << " Invalid entry months must be 1-12";
        }


        // convert numeric month to alpha 
        if (pinfo.month == "01")
        {
            month_alpha = "January";
        }

        else if (pinfo.month == "02")
        {
            month_alpha = "febuary";
        }

        else if (pinfo.month == "03")
        {
            month_alpha = "March";
        }

        else if (pinfo.month == "04")
        {
            month_alpha = "April";
        }

        else if (pinfo.month == "05")
        {
            month_alpha = "May";
        }

        else if (pinfo.month == "06")
        {
            month_alpha = "June";
        }

        else if (pinfo.month == "07")
        {
            month_alpha = "July";
        }

        else if (pinfo.month == "08")
        {
            month_alpha = "August";
        }

        else if (pinfo.month == "09")
        {
            month_alpha = "September";
        }

        else if (pinfo.month == "10")
        {
            month_alpha = "October";
        }

        else if (pinfo.month == "11")
        {
            month_alpha = "November";
        }

        else if (pinfo.month == "12")
        {
            month_alpha = "December";
        }
        else
        {
            cout << "Invalid Entry";
        }

        // check day range
        if (pinfo.month == "1" && (pinfo.day > "31" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of January";

        }
        if (pinfo.month == "2" && (pinfo.day > "31" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of Febuary";
            int number = atoi(pinfo.year.c_str());

            if (pinfo.month == "2" && number % 4 == 0)
            {
                cout << pinfo.year << " -> Leap Year!";

            }
            if (pinfo.month == "3" && (pinfo.day > "31" || pinfo.day < "1"))

                cout << pinfo.day << "is not a valid day of March";
        }

        if (pinfo.month == "3" && (pinfo.day > "31" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of March";
        }

        if (pinfo.month == "4" && (pinfo.day > "30" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of April";
        }
        if (pinfo.month == "5" && (pinfo.day > "31" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of May";
        }
        if (pinfo.month == "6" && (pinfo.day > "30" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of June";
        }
        if (pinfo.month == "7" && (pinfo.day > "31" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of July";
        }
        if (pinfo.month == "8" && (pinfo.day > "31" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of August";
        }
        if (pinfo.month == "" && (pinfo.day > "30" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of September";
        }
        if (pinfo.month == "1" && (pinfo.day > "31" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of October";
        }
        if (pinfo.month == "1" && (pinfo.day > "30" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of November";
        }
        if (pinfo.month == "12" && (pinfo.day > "31" || pinfo.day < "1"))
        {
            cout << pinfo.day << "is not a valid day of December";
        }

        // prints month, day, year 
        cout << pinfo.month << ", " << pinfo.day << ", " << pinfo.year << month_alpha << "(US) \n";
        cout << month_alpha << " " << pinfo.day << ", " << pinfo.year << "(US Expanded) \n";
        cout << pinfo.day << " " << month_alpha << " " << pinfo.year << "(US Military) \n";
        cout << pinfo.year << "-" << pinfo.day << "month_alpha" << "-" << "(International) \n";

        RunAgain = "x";
        while (RunAgain != "y" && RunAgain != "n")
        {
            cout << "Run Again (y/n)? \n" << endl;
            getline(cin, RunAgain);
        }

        // Program Exit 

        if (RunAgain == "n")
        {
            cout << "Programmer: Christopher Dresser \n\nGoodbye! Press <Enter> key to end the program... ";
            getline(cin, RunAgain);
            if (RunAgain.empty())
                break;

        }
    }
}

标签： c++struct

解决方案

您的程序非常复杂，因为您将字符串用于数值，并且因为没有其他任何东西，有很多测试什么都没有（如果您知道您在给定月份，为什么要检查您是否在其他月份之后？）。你还要检查pinfo.day < "1"所有的月份，只做一次就足够了。

还有一些错误，例如

   if (pinfo.month == "2" && (pinfo.day > "31" || pinfo.day < "1"))

2 月份从来没有 31 天，如果上面的测试是真的，表明 2 月份有一个错误，无论如何你都会这样做

       int number = atoi(pinfo.year.c_str());

       if (pinfo.month == "2" && number % 4 == 0)
       {
           cout << pinfo.year << " -> Leap Year!" << endl;

       }
       if (pinfo.month == "3" && (pinfo.day > "31" || pinfo.day < "1"))

           cout << pinfo.day << "is not a valid day of March" << endl;

所以你测试跳跃案例太晚了，你还检查了火星的案例（可能是复制/粘贴错误）。

我鼓励您将日期和月份转换为数字，并在与月份相对应的索引处包含一个包含最大可能天数/月份名称的数组，如果您只想要一个近似值，请使用 2 月的特殊管理，否则使用可用的库来检查。

当您打印错误消息时，用换行符刷新它，否则下一个打印将折叠到它。

您是否再次运行的方式也很复杂，如果通过getline进入的最后一行不为空，为什么要中止退出？

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