From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Berthelot <davidb@Magma-DA.COM>
To: nimrod99@dingoblue.net
Cc: gcc-help@gcc.gnu.org
Subject: Re: Problem with header files.
Date: Fri, 03 Aug 2001 16:43:00 -0000
Message-id: <3B6B3680.C121BA1C@magma-da.com>
References: <01080409411301.19611@Hand_Of_God>
X-SW-Source: 2001-08/msg00043.html

Ok I think it's quite easy: you forgot to specify the library for
linking, you should do:

gcc trial.c -lm

libm is the math library, when referring to a library you put -l
(instead of lib),
so -lm link with the math library.

David

Matt R wrote:

> Dear GCC Gurus,
> I have a problem getting GCC to refer to header files.
> For example the following program....
> ------------Code Begins Here------------
> #include <stdio.h>
> #include <math.h>
>
> main() {
>     float uno;
>     float  duo;
>     uno=7.778;
>     duo=sqrt(uno);
>     printf("sqrt of %f is %f \n", uno, duo);
> }
>
> ------------Code Ends Here--------------
> Produces the following message at compile time...
>
> [fakeuser@fakehost BeginC]$ gcc trial.c
> /tmp/ccBm2UFL.o: In function `main':
> /tmp/ccBm2UFL.o(.text+0x1b): undefined reference to `sqrt'
> collect2: ld returned 1 exit status */
>
> __________________________________________
>
> What is going on?  I would really appreciate your advice on this
> one.  I have to admit to being a newbie to C programing.
> I have installed glibc 2.2.12 (full install), and gcc 2.9.6-85, and
> am using RedHat 7.0 distro.  The original versions of glibc gave the
> same errors.
>
> Looking forward to your advice...otherwise I will end up doin my
> iminent assignments on DOS....a fate worse than death.
>
> Matt Redding