1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
|
From: "Klaus Eichner" <klaus_gb@yahoo.com>
Date: Sat, 26 Jul 2003 14:53:23 +0100
Newsgroups: comp.lang.c++
Subject: Re: enum count
"Clive" <clive@clive.clive> wrote in message
news:3f21e5cc$0$23611$5a62ac22@freenews.iinet.net.au...
> If you have an enum, is there any way during execution to find the number
of
> values in the enum?
> Say I have,
>
> enum great { five, ten, fifteen };
>
> How could I get the number 3 from that?
You could get the number 3 from 'great' with your own, user-defined
'Enum_Info' template:
cout << "The number of values in enum great is "
<< Enum_Info<great>::number_of_elements
<< endl;
The 'Enum_Info' template is defined as follows.
Suppose you have the following enums:
enum great { five, ten, fifteen };
enum greater { none, one, fourtytwo, fourtythree, fourtyfour };
enum even_greater { minusone, minustwo, minusthree, minusfour, minusfive,
minussix, minusseven };
You could build a template class 'Enum_Info' which uses specialisation to
register the number of elements in each enum
template <class T> class Enum_Info { };
template <> class Enum_Info<great> { static const int number_of_elements =
3; };
template <> class Enum_Info<greater> { static const int number_of_elements =
5; };
template <> class Enum_Info<even_greater> { static const int
number_of_elements = 7; };
$Id$
|
