I have created a library Lib that doesn't have a class. I want this library to have a variable that can be accessed from outside. The way I would go about this is to just declare them in the header file.

However, if I do this like so:

int myVariable;

with the .cpp-file containing only

#include "Lib.h"

I get this error message when compiling an empty sketch that includes this library:

multiple definition of `myVariable'

and for some weird reason

Multiple libraries were found for "Lib.h"

on top of that (although, this is something I have encountered before - when there is some error during the compilation, this error may come alongside it, even though there are no multiple libraries; it goes away when the other compilation errors are resolved aswell).

What is causing that error and how to resolve it?

I have created a library Lib that doesn't have a class. I want this library to have a variable that can be accessed from outside. The way I would go about this is to just declare them in the header file.

However, if I do this like so:

int myVariable = 1;

with the .cpp-file containing only

#include "Lib.h"

I get this error message when compiling an empty sketch that includes this library:

multiple definition of `myVariable'

and for some weird reason

Multiple libraries were found for "Lib.h"

on top of that (although, this is something I have encountered before - when there is some error during the compilation, this error may come alongside it, even though there are no multiple libraries; it goes away when the other compilation errors are resolved aswell).

What is causing that error and how to resolve it?