Re: Using fwrite in Ada

[Martin Krischik <krischik@users.sourceforge.net>]

Makhno wrote:

> Hello,
> I want to read and write binary data from stdin/stdout, unfortunately
> Ada's usual IO routines appear to be text only and (on Win32) convert code
> 10 to codes 10 & 13.

Not at all true:

http://en.wikibooks.org/wiki/Programming:Ada:InputOutput

Sadly the articles which describe how to attach any stream type to
stdin/stdout has not been written yet :-( .

> To get round this I'm trying to use Interfaces.C_Streams, but I don't know
> enough Ada to get them working.
> How to I get a String into the fwrite function?
> I tried
> 
> procedure MainCode is
> 
>  cptr : chars_ptr;
>  Buffer : String (1..100);

Are you sure you use the right String type?

http://en.wikibooks.org/wiki/Programming:Ada:Strings

>  vptr : voids;
> 
>  begin
> 
> -- fill Buffer with binary data here
> 
>   cptr:=New_String(Buffer);
>   vptr:=voids(cptr);
> 
>   fwrite(vptr,100,1,stdout);
>  end;
> 
> But this won't compile, the compiler says that it cannot convert the
> chars_ptr to voids. Coming from a C background, I don't understand why
> something cannot be cast to void.

Read:

http://en.wikibooks.org/wiki/Programming:Ada:Subtypes#Converting_data

and

http://en.wikibooks.org/wiki/Programming:Ada:Types:access
 
> Does anybody have any idea as to how I get binary data onto stdout?

If it is truly binary data of a fixed length of 100 bytes I would suggest
Direct I/O:

http://en.wikibooks.org/wiki/Programming:Ada:InputOutput#Direct_I.2FO

But you should really read the suggested web pages.
Martin

-- 
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Ada programming at: http://ada.krischik.com