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From: "Gerd" <GerdM.O@t-online.de>
Newsgroups: comp.lang.ada
Subject: Interfacing with C - pointer problem
Date: 30 Jan 2007 06:23:37 -0800
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Date: 2007-01-30T06:23:37-08:00
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I try to call some C code, so I wrote me a simple interface, but it 
does not what I expected.

It looks like this:

  type LPSTR is access all String;

  procedure C_Func (x : LPSTR);  -- expects an address (C-pointer, 32-
bit)
  pragma Import (STDCALL, C_Func, "C_Func");

  procedure Q is
   data : aliased String := "ABC" & Ascii.Nul;

  begin
   C_Func (data'unchecked_access);
  end Q;

This does not work correct. What I found is, that data'Address is 32 
bit and LPSTR is 64 bit.

How to manage this?

I tried a "pragma Convention (C, LPSTR);" but this gives a warning. So 
what would be the right way?

Thanks in advance,
Gerd