此文档是《21天学懂C#》这本书的pdf版，非常清晰，很适合初学者-This document is the 21 days to learn C# this book PDF version, very clear, very suitable for beginners

21天学懂C#实例源代码，便于初学者比较对照学习。熟练掌握的大神不用看了(21 days to learn C # example source code)