In programming, a variable that can be used by all modules and functions in the program. The common practice is to keep global variables to a minimum, because they can be manipulated by any ...

I read that by default, a Microsoft dll always gives each program a private copy of global variables. So that function not working would make sense, but I defined my variable in a shared data segment.

Global variables A global variable places greater demand on system resources - it needs to be retained in memory (RAM) throughout the entire execution of a program.