自己练习编写的对话框程序，实现了像XP下，简单的计算器功能，可以使用连加、减、乘除、开方、求算数平方根等功能，适合VC++入门者参考-Practice writing their own dialog procedure to achieve such as XP, a simple calculator, you can use even the addition, subtraction, multiplication and division, square root, find the