利用信号量进行多线程通讯

首先在主程序中建立两个线程，然后设置信号量，每个线程循环等待符合要求的信号量，只要满足条件，则线程执行。该例为多线程通讯的简单实例，只是展示了原理-Signal was carried out using multi-threaded communication first in the main program to create two threads, and then set the semaphore for each thread to wait for the cycle to meet the requirements of the semaphores, as long as it meets the conditions, then thread implementation. The case for multi-threaded communications simple example, but demonstrates the principle of