Xref: utzoo comp.sys.ibm.pc:44492 comp.lang.c:25952
Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!mailrus!iuvax!maytag!watstat!dmurdoch
From: dmurdoch@watstat.waterloo.edu (Duncan Murdoch)
Newsgroups: comp.sys.ibm.pc,comp.lang.c
Subject: Re: TC bug in sizeof()?
Message-ID: <1522@maytag.waterloo.edu>
Date: 15 Feb 90 20:25:28 GMT
References: <1519@maytag.waterloo.edu>
Sender: daemon@maytag.waterloo.edu
Reply-To: dmurdoch@watstat.waterloo.edu (Duncan Murdoch)
Organization: U. of Waterloo, Ontario
Lines: 22

In article <1519@maytag.waterloo.edu> I asked:
>
>As illustrated in the program below, if a structure is an odd size, and
>is compiled with Word alignment, the sizeof function rounds the size up
>one byte.  
>
>Is this a bug?

Thanks to several people who told me that it isn't a bug, but a necessary
property so that relations like sizeof(array) = sizeof(element)*(number of
elements) hold.  

One more question then:  Originally this came up because my friend wanted
to read fixed (odd) sized records from a file, using 

  while (fread(&structure,sizeof(structure),1,data)!=0)
  { ... }

Obviously sizeof() isn't the right thing to use here.  What's the recommended
way to declare that a structure is "packed", and find out its packed size?

Duncan Murdoch