Function Prototypes

Will this compile?

      #include <stdio.h>

      int main ()
      { printf ("%e newtons\n",
                CoulombsLaw (1.6e-19, 1.6e-19, 5.3e-11));
        return 0;
      }

• types and number of arguments of functions are checked

• standard type conversion if necessary

• function return type is checked

• can be compilation warning if checks fail or conversion is not possible

• so also check compiler warnings

Will this compile?

      #include <stdio.h>

      extern double CoulombsLaw (double q1, double q2, double r);

      int main ()
      { printf ("%e newtons\n",
                CoulombsLaw (1.6e-19, 1.6e-19, 5.3e-11));
        return 0;
      }

• extern keyword says that function is external and needs to be included in the link step

• statement ends with ; where body would have been