extern keyword

what is the extern keyword for.

extern allows you to use global variables defined in one file( remember they have file scope) in another file. For example:

Code:

---

//file 1
int Cats = 5
void printcats(){
        cout<<Cats;
}

//file 2

extern int Cats //declare variable in current file
void ShowCats(){
        cout<<Cats;
}

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