Path: utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!sun-barr!decwrl!megatest!djones
From: djones@megatest.UUCP (Dave Jones)
Newsgroups: comp.lang.c
Subject: Re: sizeof(struct) and padding
Message-ID: <14309@goofy.megatest.UUCP>
Date: 25 Oct 90 03:49:44 GMT
References: <1229@sun13.scri.fsu.edu>
Organization: Megatest Corporation, San Jose, Ca
Lines: 15

From article <1229@sun13.scri.fsu.edu>, by mayne@sun10.scri.fsu.edu (William (Bill) Mayne):

> 
> The $64K question is: How do I portably get the actual size of
> a structure without padding when I need that rather than
> what sizeof() tells me?

You don't. When you write structures directly to disc, it is non-portable,
period -- whether or not you write the tail-padding. Different machines will
have different internal padding, even different data formats. For most
kinds of data, text (ASCII or EBCDIC) is the perfect solution. Use fprintf()
or get fancy with a library package. I think there are some public domain
ones. Somebody will also mention Sun's XDR, which may work well for you,
particularly if your machine uses the same data-representations that Sun
machines do.