说明：  The C# programming language is a powerful and, at some nine years old, relatively mature descendant of the earlier C, C++, and Java languages. Programming with C# is lots of fun, as you’re about to find out in this book. Microsoft created C# as a major part of its .NET initiative. The company turned over the specifications for the C# language to the ECMA (pronounced “ek-ma”) international standards committee in the summer of 2000 so that any company can, in theory, come up with its own version of C# written to run on any operating system, on any machine larger than a calculator.include source code