Compilation error

[llewelly@198.dsl.xmission.com]

On Mon, 21 Feb 2000, Jose Miguel A.C.Pires wrote:

> *This message was transferred with a trial version of CommuniGate(tm) Pro*
> Hello
> 
> I'm trying to compile this simple program
> 
> #include <stdio.h>
> #include <math.h>
> 
> int main(void)
> {
>   float r=2;
> 
>   printf("A raiz de %2.0f e' %.6f", r, sqrt(r));
> 
>   return 0;
> }
> 
> but i get the following errors.
> 
> /tmp/cca110161.o: In function `main':
> /tmp/cca110161.o(.text+0x17): undefined reference to `sqrt'
> 

Add -lm to your link line:

$gcc foo.c -lm

(-lm means 'link libm.[so,a] . libm is the math library.')