C++ sort string in comparator function

[dynastysaint]

Hello there i am currently using a comparator function in STL map for sorting date of string data type in ascending value. My dates are in this format for e.g. 15OCT1990, 13SEP1980 and etc. I am using substring to split up the string so i can compare day, month, year separately. So now i have problem comparing the month portion because alphabetically "FEB" comes before "JAN". I have been thinking for hours but couldn't come up with a solution. Please advice what can i add to my current code, thanks!

struct sortMapDaily: public std::binary_function <bool, std::string, std::string>
{

  bool operator() (const std::string& lhs, const std::string& rhs)
  {

     if(lhs.substr(5,4) < rhs.substr(5,4))
     {
         return true;

     }
     else if (lhs.substr(5,4) == rhs.substr(5,4) && lhs.substr(2,3) < rhs.substr(2,3))
     {

         return true;
     }
     else if (lhs.substr(5,4) == rhs.substr(5,4) && lhs.substr(2,3) == rhs.substr(2,3) && lhs.substr(0,2) < rhs.substr(0,2))
     {
         return true;

     }
     else
     {
         return false;
     }


  }
};

[Zhuge]

You may want to make a map that associates the month name with the month number so that you can compare those. Then just look up the name and sort based on that value.

[dynastysaint]

Like this?
map<string,int>compareMonth;
compareMonth["JAN"] = 1;
compareMonth["FEB"] = 2;


But how do i pass the value to the condition lhs.substr(2,3) < rhs.substr(2,3) so that it knows "JAN" is less than "FEB"?

[Zhuge]

If lhs/rhs.substr(2,3) is the name of the month, then you can just check the same way you assigned: compareMonth[lhs.substr(2,3)] will return 1 if lhs.substr(2,3) is "JAN" and so on.