Organizing files/function in header files.

Hi all,

if i have the following
a header file called "temp.h" :

Code:

---

#ifndef TEMP_H
#define TEMP_H
double to_celsius(double fahrenheit);
#endif

---

the temp.cpp file :

Code:

---

#include "temp.h"
double to_celsius(double fahrenheit){
      double celcius = (fahrenheit - 32) * 5.0 / 9.0;
      return celcius;
}

---

the main.cpp:

Code:

---

#include "temp.h"
int main() {
    cout << to_celsius(32) << endl;
    return 0;
}

---

My question, is it necessary to include the header in "temp.cpp" and "main.cpp" ? or is it enough only "main.cpp" (because it works for me when i include it only in main.cpp).

are there different cases? or is there some best practice?

any hints or links to read more about it is appreciated

You need to include the header file in main.cpp because to_celsius must be declared before it is called in the main function.

You don't need to include the header file in temp.cpp in this case, but you should because that way the compiler will warn you if there's a mismatch between the function declaration and its definition. In other cases, there may be other things declared in the header that you will want to use in temp.cpp

alright, got it, thanks a lot