说明：  台湾的caterpillar做的Qt学习笔记，感觉比较有用，尤其对于刚刚接触Qt编程的人来说，它能帮助你从最简单的helloworld开始一步一步的深入Qt的世界。
(A document made by caterpillar from Chinese Taipei. It is useful for the beginners who just entered the Qt world. It will teach you step by step from the helloworld.)