QT GUI编程的第二个典型界面编程实例，适合初学者学习了解qt的界面编程-The QT GUI programming typical interface programming examples, suitable for beginners to learn to understand the qt interface programming

特别漂亮的Qt按钮实例，当所做界面不需要window自带的关闭和最大化按钮时使用，-Particularly beautiful Qt button instance, when the interface is done without window maximize button comes off and use,

QT 入门实例，用来计算圆的面积，适合初学者的源程序。