利用进程模拟火车票售票系统，主要是为了实现进程同步和通信，其中用到了互斥变量-train ticket sale system

火车票售票系统用户为乘客、售票员、系统管理员，功能有车票查询，售票退票，用户管理，车次管理等-Train ticket booking system user for passengers, the conductor, the system administrator, functions ticket inquiries, ticket refund, user management, trips, etc.

本例程模拟火车票售票系统。为了满足乘客的需求，必须设很多的售票窗口，每个售票窗口就像一个线程，它们各自运行，共同访问相同的数据——火车票的数量。-The routine simulation of train ticket booking system. In order to meet the needs of passengers, there must be a lot of ticketing window, each ticket window is like a thread, th