Date: Tue, 11 Apr 2006 19:12:44 -0400 From: Nicolas Blais <nb_root@videotron.ca> To: freebsd-questions@freebsd.org Cc: Jonathan Herriott <herriojr@gmail.com> Subject: Re: pow function working unexpectedly Message-ID: <200604111912.44611.nb_root@videotron.ca> In-Reply-To: <6a56d69c0604111607l5fba5939pfc6461a99a2ceab3@mail.gmail.com> References: <6a56d69c0604111554o587ce2c5ha1ff4ea20bbab0a4@mail.gmail.com> <200604111857.43171.nb_root@videotron.ca> <6a56d69c0604111607l5fba5939pfc6461a99a2ceab3@mail.gmail.com>
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--nextPart3251652.0iaCXq90ey Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline 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 bug. > > > 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 funct= ion > > > 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 gcc > > > (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 (f= rom=20 variables or functions), then the compiler could care less if it was linked= =20 with the math library or not. If your software DOES use a variable or a call from math.h (pow in this cas= e),=20 then linking with the math library is a must. Hope this answers your question, if it doesn't, post a test2.c with what yo= u=20 meant and I'll answer best I can. Nicolas. =2D-=20 =46reeBSD 7.0-CURRENT #1: Sat Apr 8 21:33:25 EDT 2006 =20 root@clk01a:/usr/obj/usr/src/sys/CLK01A=20 PGP? : http://www.clkroot.net/security/nb_root.asc --nextPart3251652.0iaCXq90ey Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (FreeBSD) iD8DBQBEPDfs4wTBlvcsbJURAlzHAKCcBTPjfzGM7OXI+hPcSaLknEbG7ACcCU4c DZNU5HINFCE7xCiG8F9MGGE= =c9oa -----END PGP SIGNATURE----- --nextPart3251652.0iaCXq90ey--
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