Using extern keyword to call functions

Question

I want to call functions defined in test.c from other.c.

Can I extern the function1 to call it? Also, do I have to use extern in <

Answer 1

Actually every function by default is extern :) - unless you declare them to be not :). It is enough if you have the prototype before the first call;

int xxx(int, int, float, double);  // prototype


int main(void)
{
  int x,y;
  float z;
  double v;

  xxx(x,y,z,v);

  return 0;
}

---

Function can be in the another .c file. You need to include the object file to the linking.

int xxx(int a, int b, float c, double d)
{
  int result;
  /* do something */

  return result;
}