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Article #2116Re: numeric_limits<float>::max
From: Jim Blandy
Date: Fri, 10 May 2002 16:55
Date: Fri, 10 May 2002 16:55
55 lines
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3058 bytes
This sounds like a real bug. However, we really can't work on something without a way to reproduce the behavior ourselves. So if you do come up with a small test program, at the very least we'll included it in our test suite, to remind us that the bug is there. Gabriel Zachmann <zach@cs.uni-bonn.de> writes: > I have a funny problem with gdb (GNU gdb Red Hat Linux (5.1-1)): > > In a C++ program I have the following two lines: > > float v = -numeric_limits<float>::max(); > fprintf(stderr,"v=%f\n", v ); > > When I run the program I always get the output > > v=-340282346638528859811704183484516925440.000000 > > However, when I run the program in gdb I sometimes get this > > 375 float v = -numeric_limits<float>::max(); > (gdb) > 376 fprintf(stderr,"v=%f\n", v ); > (gdb) > v=nan > > ^^^ > > Unfortunately, I seem to be unable to produce a small example program > exhibiting this behavior. > > I compile the program with g++ 3.0.4 using these options: > > -march=i686 -ansi -fno-default-inline -ffor-scope > -g3 -ggdb3 -Wall -W -Wpointer-arith > -Wcast-qual -Wcast-align -Wconversion -Woverloaded-virtual -Wsign-compare > -Wnon-virtual-dtor -Woverloaded-virtual -Wfloat-equal -Wmissing-prototypes > -Wunreachable-code -Wno-reorder -D_GNU_SOURCE > > Does anybody have any idea what might cause this differing behavior? > > Thanks a lot in advance, > Gabriel. > > > -- > /---------------------------------------------------------------------\ > | The mind -- what is it? | > | It is the sound of the breeze | > | Blowing through the pines in the picture. (Ikkyu) | > | | > | zach@cs.uni-bonn.de __@/' Gabriel.Zachmann@gmx.net | > | web.informatik.uni-bonn.de/~zach __@/' www.gabrielzachmann.org | > \---------------------------------------------------------------------/
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f5053,928e9af52e3d56e8 X-Google-Attributes: gidf5053,public X-Google-ArrivalTime: 2002-05-10 09:55:59 PST x-uunet-gateway: mr1.ash.ops.us.uu.net from bug-gdb to gnu.gdb.bug; Fri, 10 May 2002 16:55:57 GMT Sender: jimb@zwingli.cygnus.com Subject: Re: numeric_limits<float>::max References: <slrnadnki9.6qe.zach@fuji.informatik.uni-bonn.de> From: jimb@redhat.com (Jim Blandy) Date: 10 May 2002 11:55:48 -0500 Message-ID: <np3cx06iy3.fsf@zwingli.cygnus.com> User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.1 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Approved: bug-gdb-request@mail.gnu.org Newsgroups: gnu.gdb.bug Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!newsfeed.stanford.edu!bloom-beacon.mit.edu!nycmny1-snh1.gtei.net!cpk-news-hub1.bbnplanet.com!news.gtei.net!nntp.abs.net!uunet!dca.uu.net!ash.uu.net!spool0901.news.uu.net!wendy-fate.uu.net!bug-gdb Lines: 55