Enum to String C++

Question

I commonly find I need to convert an enum to a string in c++

I always end up doing:

enum Enum{ Banana, Orange, Apple } ;

char * getTextForEnum( int enumVal )
{
  switch( enumVal )
  {
  case Enum::Banana:
    return "bananas & monkeys";
  case Enum::Orange:
    return "Round and orange";
  case Enum::Apple:
    return "APPLE" ;

  default:
    return "Not recognized..";
  }
}

Is there a better or recognized idiom for doing this?

Perhaps use `std::map` instead of enum and switch? With a bit of wrapping into an object you could make it smart enough to be reusable as an error code lookup and handler for all your apps. — AJG85, Jun 08 '11 at 15:44
One improvement is to omit the 'default:' clause whilst turning up the warning level on your compiler and treating warnings as errors. This way, if you ever extend the list of enums, the compiler will warn and fail on your switch statement, reminding you to extend the switch as well. Some people say you should always have a default, but I believe this is a scenario where the lack of can actually help you. — Brian O'Kennedy, Jun 08 '11 at 15:46

score 53 · Accepted Answer · answered Jun 08 '11 at 15:44

53

enum Enum{ Banana, Orange, Apple } ;
static const char * EnumStrings[] = { "bananas & monkeys", "Round and orange", "APPLE" };

const char * getTextForEnum( int enumVal )
{
  return EnumStrings[enumVal];
}

answered Jun 08 '11 at 15:44

Mark Ransom

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29

Works only for continuous enums. – SasQ Dec 12 '12 at 06:40
3

@SasQ, I have a more extensive answer here: http://stackoverflow.com/a/11586083/5987 Lots of other good suggestions in that thread too. – Mark Ransom Dec 12 '12 at 15:27
A better prototype would be `const char *getTextForEnum(int) const;` my friend. Best practice. – Gangai Johann Apr 12 '16 at 17:30
9

@GangaiJohann that's only if it's a member function. My practice is to make as few changes to the code presented in the question as possible, to avoid unnecessary distractions. – Mark Ransom Apr 12 '16 at 18:02
2

And there is a code generator for that: http://www.th-thielemann.de/tools/cpp-enum-to-string.html – Th. Thielemann Nov 21 '17 at 22:37
@Th.Thielemann's comment should be the answer to this question. Thanks for making that! – Kyle Jul 05 '19 at 20:39
how can I go the other way? I want an enum from a string – ekkis Nov 17 '19 at 05:43
3

@ekkis I'd use `std::map`. – Mark Ransom Nov 17 '19 at 17:44
This does not work for enums with negative values assigned. The `std::map` approach would work, though. – damb Aug 07 '21 at 21:31
What about `getTextForEnum(500)` ? I think you should add last element like *FRUITS_MAX* and then in the function compare if given argument is smaller than this new last enum. – Jacob Nov 22 '21 at 18:04

Blagovest Buyukliev · Answer 2 · 2015-05-18T08:53:48.413

24

Kind of an anonymous lookup table rather than a long switch statement:

return (const char *[]) {
    "bananas & monkeys",
    "Round and orange", 
    "APPLE",
}[enumVal];

edited May 18 '15 at 08:53

answered Jun 08 '11 at 15:46

Blagovest Buyukliev

42,498
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score 14 · Answer 3 · answered Jun 08 '11 at 15:43

14

You could throw the enum value and string into an STL map. Then you could use it like so.

   return myStringMap[Enum::Apple];

answered Jun 08 '11 at 15:43

nathan

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Enum to String C++

3 Answers3

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