▍1. C#计算器
说明: 采用窗体程序实现一简单计算器,计算器具有加减乘除以及开方功能,功能采用Dll方式封装。(A simple calculator is realized by the window program. The calculator has the functions of addition, subtraction, multiplication and division as well as square cutting. The functions are encapsulated by DLL.)