Converting to values in an Enum Type

Hi,


I am trying to define a card class for a card game and am having trouble connecting the values provided to the constructor to some predefined enum types.


If I defined two enum types to be:

Code:

enum Rank {Two, Three, [..other cards..] Jack, Queen, King, Ace};
enum Suit {Spades, Diamonds, Clubs, Hearts};

And a constructor which took in two chars representing the rank and the suit (because the user would enter it this way via standard input):

Code:

Card (Rank r, Suit s);

e.g. Card(J,D) -> Is internally equivalent to Card(Jack, Diamonds)


How do I make that connection?


I am also given:

Code:

string Card::RankName = "23456789TJQKA";
string Card::SuitName = "SDCH";

Any help would be much appreciated!

All sorts of ways. Probably the simplest is to create a second constructor that accepts two char's and does the mapping. With C++-11 you can use a delegating constructor. If your compiler does not support delegating constructors, simply use a (private) helper function that can implement the common details from both constructors.

If you're happy to expose the user of your class to the need for mapping (which is rarely a good idea, and more indicative of a lazy programmer than anything else) create a helper function so they can create a Card using Card(MapRank('J'), MapSuit('D'));

Actually doing the mapping (eg switch statements, or by using std::map's) is implementation detail.

One easy way to do the conversion from char to enum value is

Code:

Rank rankFromChar(char r) {
    return static_cast<Rank>(RankName.find(r));
}

Since RankName is a string, you can find the position of r in the string, and cast that index to an enum value.

This is without error checking. You may also want to make sure the position isn't std::string::npos, which would mean the character wasn't found....