Message-Id: <199604120528.BAA00833@mail-e2b-service.gnn.com>
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Date: Fri, 12 Apr 1996 01:33:00
From: Jethro Wright <Jetman AT gnn DOT com>
To: djgpp AT delorie DOT com
Subject: Re: A Proper Cast for a Funtio


>> Or perhaps my comparison routine returns a long or char value.  No 
>> prob, the cast is safe and there *is* an implicit conversion (ie.
>> truncation or sign extension), but *I* know it's safe for the compiler 
>> to do.
>
>Unsafe, at least for the case that your fn returns a char.  Actually,
>there is NO implicit convertion.  What will happen is that something
>is viewed as some other type of thing.  This is never regarded as a
>convertion:  your fn is returning a char, so the compiled code puts
>the return value in AL, and returns.  Qsort() is expecting an int,
>so it checks EAX.  Anyway, the high-order 24 bits of EAX could be
>garbage, it could be neither signed, nor unsigned extended.


	Wang:  Good point, as I overlooked that possibility.  Truth is, 
I don't really use fn ptr coercion all that much, but decided to ask 
this time, since I've had a couple of occasions to use such a thing in
that past couple of months and this was as good a time as any to learn 
about this bit of C obscurity....   Jet



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 The continued survival of the human race, despite its own stupidity,
 is the strongest argument for the existence of a benevolent God.
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