From -7294935280017716058 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,13991629fd9cd1db X-Google-Attributes: gidf78e5,public From: fjh@mundook.cs.mu.OZ.AU (Fergus Henderson) Subject: Re: [was Re: Exploding integers] Date: 1997/01/21 Message-ID: <5c182m$2o5@mulga.cs.mu.OZ.AU>#1/1 X-Deja-AN: 211407745 references: <32DDD024.CEE@mds.rmit.edu.au> <5bo4qs$djf@lyra.csx.cam.ac.uk> <5boke5$r82@mpscomm.usin.com> <9701172338.aa27862@SMOKEY.ARL.MIL> <5bu8us$1f1@lyra.csx.cam.ac.uk> <32E2C09E.41C6@wizard.net> <5c0ptt$i8m@lyra.csx.cam.ac.uk> x-original-date: 21 Jan 1997 02:01:58 GMT organization: Comp Sci, University of Melbourne x-auth: PGPMoose V1.1 PGP comp.std.c++ newsgroups: comp.std.c++ originator: austern@isolde.mti.sgi.com nmm1@cus.cam.ac.uk (Nick Maclaren) writes: >James Kuyper writes: >|> Nick Maclaren wrote: >|> ... >|> > I don't suppose that there is any chance of fixing ? And I DO >|> > mean "fixing" - the current one is of little use except for checking >|> > that your own version corresponds with the compiler's idea of reality. >|> ... >|> Could you expand on that? What doesn't it do right? > >Except for FLT_RADIX, none of the the values are required to be >constant expressions. This problem is at least partially fixed in the C++ numeric_limits template. The draft C++ standard specifies the following: | 18.2.1 Numeric limits [lib.limits] | | 3 For all members declared static const in the numeric_limits template, | specializations shall define these values in such a way that they are | usable as integral constant expressions. All members of numeric_limits that have an integral type are specified as static const, so they must be integral constant expressions. However, the members of numeric_limits which are functions that return float, namely min(), max(), epsilon(), round_error(), infinity(), quiet_NaN(), signaling_NaN(), and denorm_min(), are not constant expressions. Still, in C++ it's probably not so important, since in C++ the initializer for a global const doesn't have to be a constant expression. | 18.2.1.1 Template class numeric_limits [lib.numeric.limits] | namespace std { | template class numeric_limits { | public: | static const bool is_specialized = false; | static T min() throw(); | static T max() throw(); | static const int digits = 0; | static const int digits10 = 0; | static const bool is_signed = false; | static const bool is_integer = false; | static const bool is_exact = false; | static const int radix = 0; | static T epsilon() throw(); | static T round_error() throw(); | | static const int min_exponent = 0; | static const int min_exponent10 = 0; | static const int max_exponent = 0; | static const int max_exponent10 = 0; | | static const bool has_infinity = false; | static const bool has_quiet_NaN = false; | static const bool has_signaling_NaN = false; | static const bool has_denorm = false; | static const bool has_denorm_loss = false; | static T infinity() throw(); | static T quiet_NaN() throw(); | static T signaling_NaN() throw(); | static T denorm_min() throw(); | | static const bool is_iec559 = false; | static const bool is_bounded = false; | static const bool is_modulo = false; | | static const bool traps = false; | static const bool tinyness_before = false; | static const float_round_style round_style = round_toward_zero; | }; | } -- Fergus Henderson | "I have always known that the pursuit WWW: | of excellence is a lethal habit" PGP: finger fjh@128.250.37.3 | -- the last words of T. S. Garp. --- [ comp.std.c++ is moderated. To submit articles: Try just posting with your newsreader. If that fails, use mailto:std-c++@ncar.ucar.edu comp.std.c++ FAQ: http://reality.sgi.com/austern/std-c++/faq.html Moderation policy: http://reality.sgi.com/austern/std-c++/policy.html Comments? mailto:std-c++-request@ncar.ucar.edu ]