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From: Mats Weber <Mats.Weber@elca-matrix.ch>
Subject: Re: help with pointerproblem.
Date: 1998/09/11
Message-ID: <35F92121.7C105BD4@elca-matrix.ch>#1/1
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Organization: ELCA Matrix SA
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Reply-To: Mats.Weber@elca-matrix.ch
Newsgroups: comp.lang.ada
Date: 1998-09-11T00:00:00+00:00
List-Id: <comp.lang.ada>

Roger Carlsson wrote:
 
> I'm writing a program in ada95 with opengl on W95.
> 
> I have the following definitions in GL.ads:
> 
> type GLubyte     is new C.unsigned_char;
> type GLpointer   is access all GLubyte;  -- our substitute for "void *"

The substibute for void * in Ada is called System.Address.

Just write your C subporgrams in Ada with System.Address as parameters, e.g:

   function example (X : System.Address) return Interfaces.C.Int;

   pragma Import (C, example);

   ...

   Z : VertexArray(...);

   Result := example(Z'Address);

I have always done it this way and it works great will all compilers I have used.

Another approach is using access parameters (you get better type checking this
way) but I'll let someone else decribe that (I have never used it myself).