C++ Thread, shared data

Question

I have an application where 2 threads are running... Is there any certanty that when I change a global variable from one thread, the other will notice this change? I don\'t

Answer 1

Chris Jester-Young pointed out that:

This only work under Java 1.5+'s memory model. The C++ standard does not address threading, and volatile does not guarantee memory coherency between processors. You do need a memory barrier for this

being so, the only true answer is implementing a synchronization system, right?