From:	Vik Heyndrickx <Vik DOT Heyndrickx AT rug DOT ac DOT be>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Separating two 8bit numbers from 16bit
Date:	Tue, 21 Apr 1998 14:33:57 +0200
Organization:	University of Ghent, Belgium
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Message-ID:	<353C9235.51E1@rug.ac.be>
References:	<6hi14m$e2o$1 AT hiisi DOT inet DOT fi>
NNTP-Posting-Host:	eduserv1.rug.ac.be
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Henri Ossi wrote:
> Now I'm trying to store a 16bit number as two ASCII characters to my file.
> So, I was wondering, if there's a fast way to separate a 16bit number to two
> 8bit numbers?
> 
> I know, that I can do this easily with inline asm (and I also can do it),
> but is there a fast and short way to do this in C?

If it has to be portable (my pref.):

  unsigned short w;
  unsigned char b0, b1;

  w = value;

  b0 = w % 256;
  b1 = w / 256;
  dowrite (b1);
  dowrite (b2);

If it doesn't have to be portable to big endian machines:

  union
  {
    unsigned short w;
    unsigned char b[2];
  } u;

  u.w = value;  
  dowrite (u.b[0]);
  dowrite (u.b[1]);

The second method is slightly faster.

Note: don't write these characters to a text file but to a binary file.

This question actually belongs in comp.lang.c

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