非静态类成员不是常量表达式。尝试以下操作：

 静态constexpr int = 1； 
 

I am using gcc with the -std=c++11 flag. In my class definition I have the following:

private:
   const int   January     = 1,
               February    = 2,
               March       = 3,
               ...

In my implementation I have a switch statement.

switch (currentMonth)
{
   case January:
      returnString = "January";
      break;
   case February:
      returnString = "February";
      break;
   case March:
      returnString = "March";
      break;
   ...

This seems like it should work since the months are constant; however, gcc gives me

calendar.cpp:116:12: error: ‘this’ is not a constant expression

on each case of the switch statement..Why is this wrong?

Non-static class members aren't constant expressions. Try this:

static constexpr int January = 1;