Re: pow function working unexpectedly

[Nicolas Blais]

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 = 2; // I tried these as doubles too since the pow function
> takes doubles
>      int y = 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.

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