From: j DOT aldrich6 AT genie DOT com
Message-Id: <199604100422.AA174910158@relay1.geis.com>
Date: Wed, 10 Apr 96 04:00:00 UTC 0000
To: djgpp AT delorie DOT com
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Subject: Re: A Proper Cast for a Funtio

Reply to message 2504589    from JETMAN AT GNN DOT CO on 04/09/96  2:15PM


>in order to cast down to a smaller type) when a cast is requested.  Any
>other type cast would be inherently unsafe and dangerous, so everything
>would have to be re-coded to use some other data respresentation
>scheme.  This *must* be true, otherwise the ANSI std qsort() routine
>couldn't work.

That doesn't make any sense!  What about integer to float conversions?
If the compiler didn't do translation from one type to the other, it would
result in chaos. (Imagine reading a 4-byte integer as an 8-byte double...)

Or are you distinguishing between typecasting and promotion/demotion
in expressions?  I agree that to physically modify the data when performing
a cast on a pointer type, for example, would be insane, but that isn't the idea
anyway, is it?  Besides, functions like qsort() don't actually perform any
type-dependent operations on the lists they are passed - it's up to the
comparison function to do that.  And typecasting to const void * is meaningless
except to establish that a given piece of data is 'generic', and can actually
be anything at all.  That's the basic principle on which qsort(), etc., work.

John