From String to Enum
Author
I was just wondering if there was a simple way to convert the content of a string into an enumerated const name (not the value, the index name) without having to go through a system of 'if' s ( I was thinking something along the lines of a cast).
C++
thanks [smile]
You can set up a map, but there's no straightforward automatic way to do it as C++ lacks reflection.
Author
Ok thanks. I only have like 5 enumerations so Using the 'if's is no problem, I will keep "maps" in mind for larger sets
It seems like id seen it done before by my c++ prof, but i dont remember. Do a little more research; seemed like it had something to do with an array of strings....
Quote:Original post by BTownTKD
It seems like id seen it done before by my c++ prof, but i dont remember. Do a little more research; seemed like it had something to do with an array of strings....
One way is a parallel array of strings to the enum:
enum SomeEnum{ eFoo = 0, eBar, eBaz}char* someEnumNames[] = { "eFoo", "eBar", "eBaz" };(please forgive the crappy psedo-code)
Then conversion involves linearly scanning though the enum names array until a match is found, at which point the array index can just be cast to the enum.
Unfortunately:
- It's fragile, enums and names must always be kept manually in sync, whereas a map does all of this for you
- Time is O(n), whereas a map would be O(log n)
- If needed the map can be sparse (ie. only a few enum strings map to an enum value). The array method requires your array to be as long as you have enums.
- You enums all need to be sequential (non-zero based is ok, but again adds fragility). A map can handle any enum values.
This creates an enum and a corresponding array of strings that are automatically kept in synch.
colors.h
and use it like this:
#define COLOR_LIST \ ENUM_OR_STRING( Black ), \ ENUM_OR_STRING( Red ), \ ENUM_OR_STRING( Green ), \ ENUM_OR_STRING( Blue ), \ ENUM_OR_STRING( Cyan ), \ ENUM_OR_STRING( Magenta ), \ ENUM_OR_STRING( Yellow ), \ ENUM_OR_STRING( White ) #define ENUM_OR_STRING( x ) x enum Colors { COLOR_LIST }; #undef ENUM_OR_STRING #define ENUM_OR_STRING( x ) #x char const * colorsNames[] = { COLOR_LIST }; colors.h
ENUM_OR_STRING( Black ), ENUM_OR_STRING( Red ), ENUM_OR_STRING( Green ), ENUM_OR_STRING( Blue ), ENUM_OR_STRING( Cyan ), ENUM_OR_STRING( Magenta ), ENUM_OR_STRING( Yellow ), ENUM_OR_STRING( White ) and use it like this:
#define ENUM_OR_STRING( x ) x enum Colors { #include "colors.h" }; #undef ENUM_OR_STRING #define ENUM_OR_STRING( x ) #x char const * colorsNames[] = { #include "colors.h" }; This topic is closed to new replies.
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