Re: VS 2005/C++/x64

From:

Norbert Unterberg <nunterberg@newsgroups.nospam>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 04 Dec 2007 23:38:30 +0100

Message-ID:

<#2Q$aZsNIHA.4272@TK2MSFTNGP06.phx.gbl>

Mark schrieb:

I don't know if this should be on another thread or not, but I thought I'd
ask - is there any way to tell if a variable is signed or unsigned with a
compile-time operator?
I'm having to 64-bit proof piles of our old code + 3rd party stuff, and I'm
trying to come up with some macros to help identify/work around variable size
boundaries.

I've come up with these macros that work okay, but the ISSIGNED() macro is a
little kludgy and requires a type name rather than an instance to work
because of the cast.

// either type or instance macros
#define SINTMAX ( s ) (0x7FFFFFFFFFFFFFFF >> ((sizeof(long long) - sizeof (
s )) * 8 )
#define UINTMAX ( s ) (0xFFFFFFFFFFFFFFFF >> ((sizeof(long long) - sizeof (
s )) * 8 )

// type-only macros
#define ISSIGNED ( s ) ( ( s ) (UINTMAX ( s )) != (UINTMAX ( s )))
#define INTMAX ( s ) (ISSIGNED ( s ) ? SINTMAX ( s ) : UINTMAX ( s ))
#define INTMIN ( s ) (ISSIGNED ( s ) ? -(SINTMAX ( s ))-1 : 0)

How about using numeric_limits? Maybe something like

#include <limits>

#define ISSIGNED(s) std::numeric_limits<s>::is_signed
#define INTMAX(s) std::numeric_limits<s>::max
#define INTMIN(s) std::numeric_limits<s>::min

Norbert