Extern functions?

Hi all,
I have these .CPP files ("Main.cpp" and "RandomFunction.cpp"):

Code:

---

/*
 * "Main.cpp"
 */

#include "RandomFunction.cpp"

int main()
{
    randomFunction();
}

---

Code:

---

/*
 * "RandomFunction.cpp"
 */

void randomFunction()
{
    // Do some stuff
}

---

But when I launch the program, the compiler gives me a linker error: "RandomFunction.obj : error LNK2005: "void __cdecl randomFunction(void)" (?randomFunction@@YAXXZ) already defined in Main.obj"

So how should I rewrite the code to fix the linker error (I think I should define somewhere the extern function)?


Thanks.

Petike

You don't include .cpp files. You include .h files (which should just contain the prototype of the function, not the function itself).

Quote:

---

Originally Posted by tabstop

You don't include .cpp files. You include .h files (which should just contain the prototype of the function, not the function itself).

---

It means you have to have (additionally) the following file

Code:

---

/*
 * "RandomFunction.h"
 */

void randomFunction();

---

and include it instead of cpp

Aha, so .CPP files should NEVER be included.

Now I can place the function prototype in some header file, let's say "RandomFunction.h".
But where can I place the WHOLE DEFINITION of that function? Because I don't want to have it in the "Main.cpp" file. Could you please write here the code?

Thanks

Petike

Quote:

---

Originally Posted by Petike

Aha, so .CPP files should NEVER be included.

Now I can place the function prototype in some header file, let's say "RandomFunction.h".
But where can I place the WHOLE DEFINITION of that function? Because I don't want to have it in the "Main.cpp" file. Could you please write here the code?

Thanks

Petike

---

in RandomFunction.cpp, just like you have it now.

OK,
Thanks you very much.

Petike

Hi again,
I would have one more question:
Should I use in the "RandomFunction.cpp" also the #include "RandomFunction.h" directive or it will be enough to use it just in the "Main.cpp" file?

It is always a good idea to include the "x.h" in "x.c" or "x.cpp".

There are two reasons:
1. You want to make sure that both declaration and definition of the function is the same. If you only have the one or the other, the compiler may not be able to spot the difference between the one in the header file and in the source. By including the header in the source, the compiler will say "Ah, I've seen this function before, let's make sure it matches".

2. In more advanced programming, it is probably necessary to do so, because you would have type declarations (structs, classes, etc) that you need to have in both places [and the goal of programming is to reduce duplication].

--
Mats

All right,
Thanks

Petike