stop a thread

How to stop(or cancel) a thread? Suppose I have a main thread and a worker thread, the worker thread does something looply,and when the main thread get a message indicating the process should exit, I want stop the worker thread,how to do that?I have read other thread library,their thread class supply a method called stop or cancel which stops the thread. Their Implementation is:the thread class has a data member indicating whether the thread should stop,and the thread function looply check the data member whether the thread should stop.Generally the data member's type is a bool or Event. Is it the best way to stop the thread? How the boost to deal with this? Thanks in advance.