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From: shankar@hpclscu.HP.COM (Shankar Unni)
Newsgroups: comp.lang.c++
Subject: Re: Initialization of static class members?
Message-ID: <58170034@hpclscu.HP.COM>
Date: 1 Oct 90 23:15:44 GMT
References: <114@hewey.dms.cdc.com>
Organization: Hewlett-Packard Calif. Language Lab
Lines: 42

> class butthead {
>   static int n = 2;
> 	 int c = 1;
> };
> 
> 
> Which compiler(s) is correct?  I find it a big pain to have to explicity
> initialize n & c for every constructor I may have.

This syntax is an extension to the AT&T language spec, specifically added
by g++ only.

The "official way" to initialize a static member is not in the declaration,
and not in the constructor, but in the actual definition.

A static member *must* have an actual externally-visible definition
*outside* the class body, in one compilation unit only, as in:

   // butthead.h
   
   class butthead {
      static int n;
   };
   
   // butthead.C
   
   extern int butthead::n = 0;	// definition.
   

As to initializing non-static members, use the member-initialization
syntax, as in:

   class butthead {
      int n;
      butthead() : n(0) { }
   };

Yes, you'll have to specify the initializer in each of the constructors.
-----
Shankar Unni                                   E-Mail: 
Hewlett-Packard California Language Lab.     Internet: shankar@hpda.hp.com
Phone : (408) 447-5797                           UUCP: ...!hplabs!hpda!shankar