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From: jmartin@secola.Columbia.NCR.COM (John Martinez)
Newsgroups: comp.lang.c++
Subject: use of const within a class to dimension arrays (can do?)
Message-ID: <359@secola.Columbia.NCR.COM>
Date: 19 Jun 91 17:23:10 GMT
Reply-To: jmartin@secola.Columbia.NCR.COM (John V. Martinez)
Distribution: comp.lang.c++
Organization: NCR NPD Columbia
Lines: 48

Is there any way to use a const within a class as the size of an array
which is also a member of the class?


Consider the following sample code:
(if anybody cares, it's in BC++ under DOS, but I think this is a _language_
 problem.... )
// ************************************
class Minimal {
   static const int ARRAY_SIZE;
   static int array[ARRAY_SIZE];   // "error - constant expression required"
				   //  (within the brackets, presumably)
};
const int Minimal::ARRAY_SIZE=10;
// ************************************


This generates an error, presumably because ARRAY_SIZE, while const, doesn't
count as _really_ constant until it is given a value.

Obviously there are ways to define the array I want - I could allocate it
dynamically, I could use #define for the ARRAY_SIZE, etc. but I'm trying to
find a "well-behaved" solution to what ought to be really easy to do in the
language, but isn't. I am _trying_ to follow these rules:

1) Don't use #define if you can use a const (type-checking, etc.)
2) Don't make things visible where they shouldn't be; in this case, ARRAY_SIZE
   is specific to the implementation of Minimal and no where else, so ideally,
   it shouldn't be visible to any other other code.
3) Use "constants" (loosely defined to include #defined values) instead of
   hardcoded values whenever possible and especially if the value will be
   referenced all over and is likely to be modified as the program evolves.
4) In general, if you can do something just as easily without using the heap,
   do it that way.


So, is there any "nice" way to do what I want to do, or do I have to "cheat"?

Thanks.

-(--John
jmartin@secola.Columbia.NCR.COM (upper/lower case IS significant!)

-- 
John V.Martinez
NCR Network Products Division
jmartin@secola.Columbia.NCR.COM
(803)739-7671 vplus:633-7671