Printing enum name as string

[vinodar]

Hi dears,

Since sometime now I am thinking how can it be made possible to convert an enum name as a string, given the enum value. This is especially useful if you use enums as error values and want to trace these out as strings.

Conside the following

enum enMyErrorValue
{
  ERROR_INVALIDINPUT = 0,
  ERROR_NULLINPUT,
  ERROR_INPUTTOOMUCH,
  ERROR_IAMBUSY
}

//I want a function as follows
void vPrintError(enMyErrorValue enError)
{
//YOUR CODE HERE;-)
}
void main()
{
 vPrintError((enMyErrorValue)1);
}
//which should output as below

 vPrintError(enMyErrorValue enError)
"ERROR_NULLINPUT"

Hope you got my idea..

Thanks,
vinod

[Duthomhas]

You can use the preprocessor to do that iff you explicitly name the enum. For example:

#define stringify( name ) # name

enum enMyErrorValue
  {
  ERROR_INVALIDINPUT = 0,
  ERROR_NULLINPUT,
  ERROR_INPUTTOOMUCH,
  ERROR_IAMBUSY
  };

const char* enMyErrorValueNames[] = 
  {
  stringify( ERROR_INVALIDINPUT ),
  stringify( ERROR_NULLINPUT ),
  stringify( ERROR_INPUTTOOMUCH ),
  stringify( ERROR_IAMBUSY )
  };

void vPrintError( enMyErrorValue enError )
  {
  cout << enMyErrorValueNames[ enError ] << endl;
  }

int main()
  {
  vPrintError((enMyErrorValue)1);
  }

The stringify() macro can be used to turn any text in your code into a string, but only the exact text between the parentheses. There are no variable dereferencing or macro substitutions or any other sort of thing done.

For example, you could say:

int main()
  {
  cout << stringify( Hello world! ) << endl;  // (leading and trailing whitespace is ignored)
  }

Hope this helps.

[vinodar]

Thanks Duoas. In this way there s an overhead in code size because of the const string array:-(

Just wondering whether there could be also another way to accomplish the goal without this overhead!

[jsmith]

There is no way to avoid the overhead. Somewhere in your executable there must exist the enum values as strings in order to be able to print them.

[Zaita]

Instead of using an enum. Create another file called "Translations.h" or something. Inside each of them have something like

#define ERROR_IAMBUSY "I am busy" 

This is a common technique that is used when writing multi-language software. You put all of the strings used in your program in this file (not just errors) so the translators only have to work on 1 file to translate your application :)