CStdString:一个跨平台的字符串类实现¶

//  FILE:  StdString.h
//  AUTHOR: Joe O'Leary (with outside help noted in comments)
//
//      If you find any bugs in this code, please let me know:
//
//              jmoleary@earthlink.net
//              http://www.joeo.net/stdstring.htm (a bit outdated)
//
//      The latest version of this code should always be available at the
//      following link:
//
//              http://www.joeo.net/code/StdString.zip (Dec 6, 2003)
//
//
//  REMARKS:
//      This header file declares the CStdStr template.  This template derives
//      the Standard C++ Library basic_string<> template and add to it the
//      the following conveniences:
//          - The full MFC CString set of functions (including implicit cast)
//          - writing to/reading from COM IStream interfaces
//          - Functional objects for use in STL algorithms
//
//      From this template, we intstantiate two classes:  CStdStringA and
//      CStdStringW.  The name "CStdString" is just a #define of one of these,
//      based upone the UNICODE macro setting
//
//      This header also declares our own version of the MFC/ATL UNICODE-MBCS
//      conversion macros.  Our version looks exactly like the Microsoft's to
//      facilitate portability.

"Performance" is a fairly encompassing term. Most of the performance differences will 
come down to the performance of std::string vs CString. That depends upon your 
particular implementation of basic_string, over which I have no control

For the performance of various CString-facade functions (e.g. format), well at this point 
I am long past comparing those or worrying about it. It is not going to make a difference 
in 99% of the cases. You would have to be doing some monster-level of string processing 
for it to matter.

If that sounds like a bit of a dismissal, I suppose it is. This class is mostly meant to 
help people transition over from CString to std::string with a minimum of code-rewrite. 
To help you get off of MFC> The idea is that you can get your code running right away and 
then start refactoring any important string processing code to use basic_string properly, 
in the most efficient way you see fit. This class is not meant to be used alongside CString. 
But if it must, well you can then always use CString instead. This class coexist well with it.

-Joe

Joe's CStdString is in fact a derived class from std::string.

Anyway, bad thing - good thing: CStdString has no own members. It's a straightforward 
wrapper for one/two byte instantiations of std::basic_string with the convenience of 
most features that MFC CString offers and a wide usability. I used it on Linux more 
than 10 years ago and on Win32 where I couldn't use MFC. Joe's work on it started 1998 
with help of ~50 people within 7 years of development. I think they've managed the 
poorly side effects being in the template.

CStdString key = "hello";
char * cKey = const_cast<char *>(key.c_str());