用C#软件编写的图书馆管理系统，图书馆书本信息等基本信息-Software written in C# library management system, library books, information and other basic information

OC写的一个关于三角函数的计算器功能 关于分类以及协议， Programming in OC书上的 chapter11中的第四题-The functions sin(), cos(), and tan() are part of the C Standard Library (as scanf () is). These functions are declared in the system header file math.h, which is automatically impo