sizeof(enum) ???

[Utumn0]

Hello gurus,

I know this question doesn't really belong to VC++ section, but here goes anyway....

I'd like to automatically detect how many elements my 'enum' data structure contains, something like

enum ENUM1 { A = -4, B, C, D, E };

printf("%d\n", MagicFunctionThatReturnsNumOfElementsInENUM1() );

??? sizeof(ENUM1) always returns 4

I guess I could write

int MagicFunctionThatReturnsNumOfElementsInENUM1()
{
return (E-A+1);
}

but then I gotta know the names of the first and last element of the enum...
Furthermore, this wouldn't work with enums like this

enum ENUM1 { A, B, C=56, D, E };

Any ideas? Is it even doable?

[kodeguruguy]

The easiest way for me whenever I need such a functionality is, the following.

enum DATA {
 A = 0,
 B,
 C,
 D,
 E,

 Total
}

This way Total will have the total number of elements, excluding Total itself. So to get the size, do the following

DATA Data;
int totalElements = Data.Total;

Just make sure you intial value is 0.

With the function you had in mind and even with my recommendation be carful with the following

int MagicFunctionThatReturnsNumOfElementsInENUM1()
{
return (E-A+1);
}

Just make sure you don't have the following type of enumeration, or else your function will give you the incorrect results

enum ENUM1 { 
 A = -4, 
 B, 
 C, 
 D = 1000000, 
 E };

Your function would return 1000001 - (-4) + 1 = 1000006, which is of course incorrect.

[Mercantilum]

From your code it is not possible imo, however if you don't mind calling a C program, or a simple Perl script...

open F, "enum.h" or die "couldnt open";

while (<F>) { print scalar (tr/,//)+1 if (/\benum\b/); }

works only with enum on a line by itself, with no 'enum'or ',' comment...