Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: %p and different pointer representations
Message-ID: <16112@mimsy.UUCP>
Date: 24 Feb 89 21:02:55 GMT
References: <9382@bloom-beacon.MIT.EDU> <234@mstan.Morgan.COM>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 21

In article <234@mstan.Morgan.COM> dff@Morgan.COM (Daniel F. Fisher) writes:
>To what type should a pointer argument be cast when passing it to
>fprintf() for printing using the %p conversion specifier?

Put it this way: `%p' prints one (void *).

>First Example: In an IBM-PC implementation with small-data,
>large-code, the data pointers (int *), (char *), etc. are all 16
>bits., but function pointers (int (*)()), etc. are all 32 bits.
>So if I wish to print a function pointer, I cannot cast it to a
>data pointer without losing information.

Yes.  Moreover, since sizeof(void *)==sizeof(char *)==2, when you
print a pointer-to-function using %p and a (void *) cast (on that
machine in that model), you will lose some information.

I think this is what is known as an oversight (and goes to show why
standards committees should avoid inventions)....
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris