How to make variable accessible to all application?

[Mafioso]

Hi, I've got many classes and all of them needs one variable, how can I declare that variable so it can be accessible to all my classes?

[Athar]

By declaring it a header file that is included by all translation units, for example.

[Mafioso]

Create a header with global variables and then include it in all program headers? It throws an error C2086: 'int i' : redefinition every time I include global variable header

[Athar]

I hope you aren't planning to create a global variable called i of all things.
If it's not a constant, you'll have to declare it in the header as extern int not_i_please; and instantiate it in one of your translation units.