Variable scope issues

[DeadEli]

I am writing an application that uses multiple .cpp and .h files and I want to use the same variable in multiple files. I tried declaring it in one header and including that header to the .cpp files I need the variable in, but the compiler says that I am declaring the variable multiple times. How can I use the same variable in multiple .cpp files?

[Moschops]

Here's a thread covering the same thing: http://www.cplusplus.com/forum/beginner/59607/