Date: Tue, 11 Apr 2006 23:27:52 +0000 From: "Jonathan Herriott" <herriojr@gmail.com> To: "Nicolas Blais" <nb_root@videotron.ca> Cc: freebsd-questions@freebsd.org Subject: Re: pow function working unexpectedly Message-ID: <6a56d69c0604111627x78760975g8a8112c0d90f9ea@mail.gmail.com> In-Reply-To: <200604111912.44611.nb_root@videotron.ca> References: <6a56d69c0604111554o587ce2c5ha1ff4ea20bbab0a4@mail.gmail.com> <200604111857.43171.nb_root@videotron.ca> <6a56d69c0604111607l5fba5939pfc6461a99a2ceab3@mail.gmail.com> <200604111912.44611.nb_root@videotron.ca>
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With reference to my first example given is what I was talking about.=20 The first example properly ran with just compiling with: gcc test.c Here's the first example again: > > > > #include <stdio.h> > > > > #include <math.h> > > > > > > > > int main() > > > > { > > > > printf("%f\n", pow(2,3)); > > > > return 0; > > > > } Thanks, Jon On 4/11/06, Nicolas Blais <nb_root@videotron.ca> wrote: > On Tuesday 11 April 2006 19:07, Jonathan Herriott wrote: > > Question then. Why would it work when I don't use variables if I > > don't include the library? This question is just out of curiosity. > > > > On 4/11/06, Nicolas Blais <nb_root@videotron.ca> wrote: > > > On Tuesday 11 April 2006 18:54, Jonathan Herriott wrote: > > > > I just want to make sure I'm not being stupid before I send in a bu= g. > > > > The problem seems to be with gcc when using the pow function in the > > > > math.h library. Here's code that works: > > > > > > > > #include <stdio.h> > > > > #include <math.h> > > > > > > > > int main() > > > > { > > > > printf("%f\n", pow(2,3)); > > > > return 0; > > > > } > > > > > > > > > > > > Now, the following will not compile: > > > > > > > > #include <stdio.h> > > > > #include <math.h> > > > > > > > > int main() > > > > { > > > > int x =3D 2; // I tried these as doubles too since the pow fun= ction > > > > takes doubles > > > > int y =3D 3; > > > > > > > > printf("%f\n", pow(x,y)); > > > > return 0; > > > > } > > > > > > > > I compiled both programs using: > > > > gcc test.c > > > > > > > > The second example gives the following error: > > > > > > > > /var/tmp//ccxtkMwv.o(.text+0x45): In function `main': > > > > : undefined reference to `pow' > > > > > > > > If I comile with g++, I have no issues. Are these results that I > > > > should have? If so, why? If not, I'm going to submit the bug on g= cc > > > > (or the linker, but I'm guessing it's the same group). > > > > > > > > Thanks, > > > > Jonathan Herriott > > > > > > gcc -lm test.c works. You forgot to include the math library. > > > > > I'm not sure I get your question, but if your not using the math library > (from > variables or functions), then the compiler could care less if it was link= ed > with the math library or not. > If your software DOES use a variable or a call from math.h (pow in this > case), > then linking with the math library is a must. > > Hope this answers your question, if it doesn't, post a test2.c with what = you > meant and I'll answer best I can. > > Nicolas. > > > > -- > FreeBSD 7.0-CURRENT #1: Sat Apr 8 21:33:25 EDT 2006 > root@clk01a:/usr/obj/usr/src/sys/CLK01A > PGP? : http://www.clkroot.net/security/nb_root.asc > >
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