Global Variables, include files and classes

Hello, it seems i've run into some problems using an API that uses global variables. To make things easier to implement I encapsulated all the code I needed into a class and then in a different program I include the class defintion and make instances of it to interface with the API. Problem is that there is a global variable in the API that it forces me to use and it just doesn't seem to be working.

How would global variables work in this sense? In my program I include the class definitions at "ctk_RAPIDobj.H" and in the "ctk_RAPIDobj.H" file I include the API's header file "RAPID.H" where the global variable is declared "extern int RAPID_num_contacts."

Although everything compiles fine it seems that the global variable never changes. I know this has to do something with the setup I'm using because if I just make a program and include "RAPID.H" and run some functions the global variable changes as expected.

I know this kind of vague but if there is some glaring thing that pops out please let me know. Thank you in advance for your help.

Is it declared like this?

Code:

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extern int RAPID_num_contacts;

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Or is it initialized?

Code:

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extern int RAPID_num_contacts= 100;

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Because if it's initialized, the compiler ignores the extern keyword and declares another variable.