c++ - 试图 Cout 函数的返回

Question

我是 C++ 的新手，我在使用这段代码时遇到了问题:

string output_date(int day, int month, int year){
    string date;
    if ((day > 0 && day <= 30) && (month > 0 && month <= 12) && (year >= 2013)){
        switch (month){
          case 1: date = day + " JAN " + year; break;
          case 2: date = day + " FEB " + year; break;
          case 3: date = day + " MAR " + year; break;
          case 4: date = day + " APR " + year; break;
          case 5: date = day + " MAY " + year; break;
          case 6: date = day + " JUN " + year; break;
          case 7: date = day + " JUL " + year; break;
          case 8: date = day + " AUG " + year; break;
          case 9: date = day + " SEP " + year; break;
          case 10: date = day + " OCT " + year; break;
          case 11: date = day + " NOV " + year; break;
          case 12: date = day + " DEC " + year; break;
        }
    }
    return date;
}

当我尝试做的时候:

cout << output_date(22,12,2013);

什么也没有。我做错了什么？

Answer 1

我建议使用 stringstream 并从流中返回一个字符串:

stringstream date;
    if ((day > 0 && day <= 30) && (month > 0 && month <= 12) && (year >= 2013)){
        switch (month){
          case 1: date << day << " JAN " << year; break;
          case 2: date << day << " FEB " << year; break;
          //yadda yadda.....
        }
    }
return date.str();

为此，您需要包含 header <sstream>