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From: falk@peregrine.Sun.COM (Ed Falk)
Newsgroups: comp.graphics
Subject: Re: A bug in PBM software (.pcx => pbm)
Message-ID: <140535@sun.Eng.Sun.COM>
Date: 12 Aug 90 03:31:16 GMT
References: <1990Aug7.200352.1484@ucselx.sdsu.edu>
Sender: news@sun.Eng.Sun.COM
Organization: Sun Microsystems, Mt. View, Ca.
Lines: 29

In article <1990Aug7.200352.1484@ucselx.sdsu.edu> brian@ucselx.sdsu.edu (Brian Ho) writes:
>I have find a bug (may not appear in other system) in the PBM software.
>The bug is in the program which converts a .PCX (paint brush image format)
>to a Pbm portable bitmap.
>
>The bug (very small) appear at line 102 in program "pcxtopbm.c" which is
>under /pbmplus/pbm/.  The orignal code read :
>
>    if (b & 0xC0 == 0xC0) 
>      ..
>      ..
>
>However, some system (e.g. Sun 3/50) does not like this.  It miss interpret it
>as  
>    if (b & (OxCO == 0xC0) 
>      ..
>      ..

According to "The C Programmer's Handbook" by AT&T Bell Labs, this is
the correct behavior.  If you find a compiler that *doesn't* parse
this way, contact the vendor immediately.

(personally, I think this is the wrong order of precedence, but K&R
defined it that way so that's the way it is.)

	-ed falk, sun microsystems -- sun!falk, falk@sun.com
	"What are politicians going to tell people when the
	Constitution is gone and we still have a drug problem?"
			-- William Simpson, A.C.L.U.