说明：  在开发过程中，我们常常会遇到ASCII、Unicode以及MBCS等不同类型的字符串，而且还需要经常进行转换操作。本文先介绍字符的编码方式、各种基本字符串类型，然后说明相关的帮助类，如CComBSTR、_bstr_t、CString和basic_string等，最后讨论在它们之间以及和其他的数据类型的转换方法。
(In the development process, we often encounter ASCII, Unicode and MBCS and other different types of strings, but also frequently change operation. This article first introduces the character encoding of basic string type, and then explain the relevant helper class, such as CComBSTR, _bstr_t, CString and basic_string, etc. Finally, and between them and other data types of conversion methods.)