Question

我正在构建一个代码，该代码需要一个月的字符串，并且我想使用重载增加本月的时间，以便我可以得到2月。

好吧，我尝试使用switch case语句将month转换为1到12之类的数字，我增加了该值，但是现在我需要另一个switch case将数字再次转换为string。

class DayOfYear
{
    private:
        int day;
        string month;
    public:
        DayOfYear(){}
        DayOfYear(int d, string m){
            day = d;
            month = m;
            if(d > 31 && d < 1){
                cout<<"Invalid input."<<endl;
            }
        }

        string check()           //To check the month 
        {
            switch(month)
            {
                case "January":
                    return 1;
                    break;
                case "February":
                    return 2";
                    break;
                case "March":
                    return 3;
                                        break;

                                // similarly upto november


                case "December":
                    return 12;
                    break;
                default:
                    cout<<"Invalid Input.";
                    break;
            }
        }

        DayOfYear operator++(){
            DayOfYear d;
            d.day = day++;
            if(d.day>31){
                d.day = 1;
                                ++d.month;

            }
        }

我不希望回答，我希望得到方法。

Answer 1

您不能在C ++中打开std :: string。看来您想做这样的事情：

#include <string>
#include <cctype>
#include <map>

const char* intAsMonth(int index)
{
  if(index < 1 || index > 12)
    return "invalid";

  const char* const months[] = { 
     "january",
     "february",
     "march",
     "april",
     "may",
     "june",
     "july",
     "august",
     "september",
     "october",
     "november",
     "december"
   };
   return months[index - 1];
}

int monthAsInt(std::string month)
{
  // make lower case
  std::transform(month.begin(), month.end(), month.begin(),
    [](char c){ return std::tolower(c); });

  static std::map<std::string, int> months = { 
     {"january", 1},
     {"february", 2},
     {"march", 3},
     {"april", 4},
     {"may", 5},
     {"june", 6},
     {"july", 7},
     {"august", 8},
     {"september", 9},
     {"october", 10},
     {"november", 11},
     {"december", 12}
   };
   auto it = months.find(month);
   if(it == months.end())
     return -1; // did not find
   return it->second;
 }

 int nextMonth(int month)
 {
   if(++month > 12) month = 1;
   return month;
 }

 int prevMonth(int month)
 {
   if(--month < 1) month = 12;
   return month;
 }

 std::string nextMonth(const std::string& month)
 {
   return intAsMonth(nextMonth(monthAsInt(month)));
 }

 std::string prevMonth(const std::string& month)
 {
   return intAsMonth(prevMonth(monthAsInt(month)));
 }

我们如何将字符串转换为数字和可逆？

1 个答案: