convert string to enum
Author
sorry <correction>
Hi everyone.¨
can someone help me to get an idea how to convert
a string to enum type.
exempel
enum CAVE
{
ROCK = 1,
STONE = 2
};
and then when i read in a string from lets say a textfile like
ifstream fin("info.txt",ios_base::in);
char str[20];
fin >> str;
and try to convert it like
unsigned int MyFlag = CAVE(str);
but it dosent work...
what should i do?
im newbie so i hope someone has a clue, what to handle with this kind of problem.
most gratefully
voy
At runtime the identifiers used to designate enums don't exist. If you want a mapping between strings and enums you have to implement it manually. One approach is to use a std::map. Ex:
std::map<std::string, CAVE> CAVE_map; CAVE_map["ROCK"] = ROCK; CAVE_map["STONE"] = STONE; CAVE value = CAVE_map[str];
You could simply use a switch statment or series of if, else ifs.
enum pets{ CAT, DOG, FISH, HAMSTER, SNAKE }int MyPet;std::ifstream File(FileName);std::string Enum;File >> Enum;if(Enum == "CAT")MyPet= CAT;if(Enum == "DOG")MyPet= DOG;....Quote:Original post by Grain
You could simply use a switch statment or series of if, else ifs.
It's illegal to do a switch statement on strings in C++.
Quote:Original post by Grain
You could simply use a switch statment or series of if, else ifs.
That won't work in C++. If you really want to avoid using a std::map then you can use a parrallel array.
(pseudo code):
enum CAVE{ ROCK = 0; STONE, CHEESE, LAST_CAVE = CHEESE}string[LAST_CAVE] CAVE_STRS = { "Rock", "Stone", "Cheese" };stringToEnum(string str){ for (int i=0; i<LAST_CAVE; i++) { if (str.equals(CAVE_STRS) return i; } // Not found! assert (false);}The only snag being that you have to be careful to keep your enum and string array in sync, otherwise you'll convert wrongly.
yes,
good idea,
But it seems that string class dosent include the member equals ??
and second,
it proberly gonna work for numbers that is in serie. like 0 1 2 3 4 and so on.
good idea,
But it seems that string class dosent include the member equals ??
and second,
it proberly gonna work for numbers that is in serie. like 0 1 2 3 4 and so on.
Quote:Original post by Anonymous Poster
yes,
good idea,
But it seems that string class dosent include the member equals ??
Like I said, that's only pseudo code, at least put some effort in yourself. [razz] If you're using std::string IIRC it has an overloaded == operator. Else, strcmp.
Quote:it proberly gonna work for numbers that is in serie. like 0 1 2 3 4 and so on.
Well unless you're deliberatly messing with it, enums always are. If you need values that start other than zero, add an offset (similar to LAST_CAVE). If you need non-continuous enum values then you're going to have to go with a std::map.
like i said before...
im newbie so please be patient, thats explain why i have to ask
about members like equals. seems logic?
http://www.gamedev.net/community/forums/images/icons/icon91.gif
http://www.gamedev.net/community/forums/images/icons/icon91.gif
thanks for the advice anyway.
I think i found a solution in the end.
and it ends up in something like
(also a pseudo code)
enum CAVE
{
MAP1 = 12,
MAP2 = 45
};
int convertStr2Enum(char *str)
{
if (strcmp(str,"MAP1")==0)
return MAP1;
if (strcmp(str,"MAP2")==0)
return MAP2;
// nothing
return -1;
}
im newbie so please be patient, thats explain why i have to ask
about members like equals. seems logic?
http://www.gamedev.net/community/forums/images/icons/icon91.gif
http://www.gamedev.net/community/forums/images/icons/icon91.gif
thanks for the advice anyway.
I think i found a solution in the end.
and it ends up in something like
(also a pseudo code)
enum CAVE
{
MAP1 = 12,
MAP2 = 45
};
int convertStr2Enum(char *str)
{
if (strcmp(str,"MAP1")==0)
return MAP1;
if (strcmp(str,"MAP2")==0)
return MAP2;
// nothing
return -1;
}
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