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From: blarson@skat.usc.edu (Bob Larson)
Newsgroups: comp.os.os9,comp.lang.c
Subject: Re: Bugs in OS9/68K C-Compiler ?
Message-ID: <13117@oberon.USC.EDU>
Date: 28 Oct 88 05:23:27 GMT
Article-I.D.: oberon.13117
References: <147@fbihh.UUCP> <636@tuvie>
Sender: news@oberon.USC.EDU
Reply-To: blarson@skat.usc.edu (Bob Larson)
Organization: USC AIS, Los Angeles
Lines: 26

In article <636@tuvie> rzmul3@tuvie (Uni Leoben) writes:
>For the 'return 0 != ptr' problem : I don't know why, but 'return ptr != 0'
>works. Apparently the compiler automatically casts integers to pointers
>on comparisons but doesn't cast pointers to integers. I don't know what
>K&R says to this case. Perhaps someone with more C insight could comment
>on this.

The order of the comparison dosn't matter, 0 must be converted to the
approprate type.

char *ptr;
return 0 != ptr;

is equivelent to:

char *ptr;
return (char *)0 != ptr;

(I'm quite sure K&R, H&S, K&R-II, and the ANSI drafts all argee on this.)
[Microware is gradually converting from a K&R based compiler to an ANSI
one, when I talked to him a few years ago Kim Kempf (microware's C
compiler guru) was on the ANSI committee.]
-- 
Bob Larson	Arpa: Blarson@Ecla.Usc.Edu	blarson@skat.usc.edu
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