虽然Windows下可视化开发工具如VC、Delphi、C＋＋ Builder等都有专用的定时器控件Timer，而且使用很方便，可以实现一定的定时功能，但最小计时精度仅为55ms，且定时器消息在多任务操作系统中的优先级很低，不能得到及时响应，往往不能满足实时控制环境下的应用。不过Microsoft公司在Win32 API函数库中已经为用户提供了一组用于高精度计时的底层函数，如果用户使用得当，计时精度可到1ms。这个计时精度、对于一般的实时系统控制完全可以满足要求。现将由C＋＋ Builder 4.0提供的重新封装后的一组与时间相关的主要接口函数（函数名、参数、功能与Win32 API基本相同）说明如下：

-visual development tools such as Visual C + +, Delphi, C + + Builder and others all have dedicated Timer timer control, but it is convenient. can achieve a timing function, but only the minimum time of 55 ms accuracy. Timer news and multi-task operating system in the low priority that is not to respond in a timely manner, often fail to meet the real-time control environment applications. However, Microsoft Corporation in the Win32 API function has been to provide the user with a group for high-precision the bottom was a time function, if the user is properly utilized, time accuracy can be a ms. Accuracy this time, and for most of the real-time control system can meet the requirements. Now by C + + Builder 4.0 for the re-packaging of a group associated with the time the main interface funct