Path: utzoo!utgpu!watserv1!watmath!att!dptg!mtunh!netnews
From: netnews@mtunh.ATT.COM (netnews dptg)
Newsgroups: comp.lang.c
Subject: Re: IsUnsigned() function?
Message-ID: <2936@mtung.ATT.COM>
Date: 20 Jul 90 04:12:28 GMT
References: <1990Jul16.214155.5087@Neon.Stanford.EDU>
Reply-To: rdh@mtung.ATT.COM (Ralph Hayon)
Organization: AT&T Bell Laboratories, Middletown, NJ, USA
Lines: 37

How about this:

	IsUnsigned (a) 
	int a;
	{
		return( !(a >> ((sizeof(int)*8)-1)));
	}

The only real assumption that this function makes is that
there are 8 bits in a byte (a fair assumption I think).

If you don't care about portability (I do, though) and like to make
more assumptions (like the size of the int on your system)
you can make it even shorter:

4 byte int:

	IsUnsigned (a) 
	int a;
	{
		return( !(a >> 31));
	}

2 byte int:

	IsUnsigned (a) 
	int a;
	{
		return( !(a >> 15));
	}

BTW: What you have experienced says much more about Microsoft than
     about yourself. Don't let it eat you.

Ralph Hayon
AT&T Bell Laboratories, 
Middletown, NJ