From owner-freebsd-chat  Sun Aug 29 18:44: 3 1999
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Date: Mon, 30 Aug 1999 01:17:51 +0100
From: Ben Smithurst <ben@scientia.demon.co.uk>
To: Mark Ovens <mark@ukug.uk.freebsd.org>
Cc: chat@freebsd.org
Subject: Re: Correct casting in ANSI C
Message-ID: <19990830011750.A37445@lithium.scientia.demon.co.uk>
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Mark Ovens wrote:

> To achieve *strict* ANSI compliance, what is the correct way to
> use cast(s) in the following code.
>
> gcc doesn't complain, even with ``-Wall'',

Or `-Wall -ansi -pedantic'.

> but Sun's ANSI C compiler
> gives a warning like "the semantics of SCONV change in ANSI C; use
> an explicit cast". Do I need to cast each int (& the literal 1000),
> or just cast the whole expression?
>
>         int i = 123, j = 57, k = 500;
>         double d;
>
>         d = i / j + k / 1000;

Hmm. I think you can just cast one part of each division, to make it do it
in floating point, or something. How about

d = (double)i / j + (double)k / 1000;

or, somewhat cleaner,

d = (double)i / j + k / 1000.0;

Otherwise it will just do an integer division (or so it appears -- I'm
not an expert at this sort of thing). It seems you need to get some
floating point into each division.

You might like to go and ask this in comp.lang.c, where all the ANSI C
experts hang out.

Incidentally, your mail came through with lines padded out to 80
characters with trailing spaces, did you break something? I don't think
it's my end, I haven't noticed it on anything else.

-- 
Ben Smithurst            | PGP: 0x99392F7D
ben@scientia.demon.co.uk |   key available from keyservers and
                         |   ben+pgp@scientia.demon.co.uk


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