Sending 'Messages' between objects
I know one of the great advantages of OO is the ability for objects to communicate with each other. In the past, I have not managed to do this: instead I just have each method called from main (or wherever the core of my program is), return the results, then if necessary use that info to send to another object.
My problem is: how would I send messages between objects? If each class is in a separate file, they shouldn't be directly accessible to each other. The only way I can think of is to have a pointer in every object to every other object, and send the messages to that.
Am I missing something?