From: "A. Sinan Unur" <asu1 AT cornell DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: if(a==0xff) warning
Date: 11 Aug 2001 19:11:55 GMT
Organization: Cornell University
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Kai Dietrich <toepferei DOT dietrich AT t-online DOT de> wrote in 
news:9l1dan$nq3$01$1 AT news DOT t-online DOT com:

> Hi!
> 
> What does that mean:
> 
> char a;
> 
> a=0xff;
> 
> if(a==0xff)foo();
> 
> 
> C:\>gcc foo.cpp -o foo.exe
> foo.cpp: In function `void main()':
> foo.cpp:598: warning: comparison is always false due to limited range of
> data type

0xff is an unsigned quantity whereas char, in this case, is signed. a check 
of limits.h in djgpp\include shows that signed char ranges from -128 to 
127. hence a can never equal 255.

> foo.cpp: In function `void main()':

incidentally, the proper return type for main is int not void.

sinan.


-- 
--------------------------------
A. Sinan Unur
http://www.unur.com/