"Undefined Reference" to pow and sqrt even though math.h header is there

Compiling this code tells me that there is no reference to pow() or sqrt(). The book didn't tell me under which header these functions are located but I assume they are under math.h. Am I missing something here?

Code:

---

#include <stdio.h>
#include <math.h>

double hypotenuse(double a, double b);

int main()
{
  double side1, side2;

  printf("Enter side 1: ");
  scanf("%lf", side1);
  printf("Enter side 2: ");
  scanf("%lf", side2);
  printf("%.2f\n", hypotenuse(side1, side2) );

  return 0;
}

double hypotenuse(double a, double b)
{
  return sqrt( pow(a, 2) + pow(b, 2) );
}

---

If you're using gcc as your compiler, try adding -lm to the end of your compile line to link in the math library.

> scanf("%lf", side1);
And don't forget the & either when using scanf

gcc -W -Wall -ansi -pedantic -O2 foo.c
Tells you when you make a mess of printf/scanf conversions (amongst other things)

That did it!

What does the -lm argument do?

Is there anyway to get cc to tell me if I made a mess(should I be using gcc instead of cc?)?

Thanks guys!

-l specifies an additional library to search
m is the name of the library, in this case, its libm.a

-lfoo always maps to libfoo.a on a Unix/Linux system.

> should I be using gcc instead of cc?
Maybe you already are - cc is mapped to gcc on my box.

ahh, thank you