Friday, April 28, 2006

The history of CString...

CString really wasn't always as likeable as it is today. If one were to compare the CString of Visual Studio 7.x and better with the class supplied by MSVC 6.0, one might not be wrong in judging the erstwhile version as relatively inflexible, and restrictive.

What made CString of yesterday "inflexible"?

1.Only for MFC-folks!

Yes... CString with MSVC 6.0 was notoriously connected to MFC Projects as if other project types didn't have any need for a TCHAR String Wrapper Class! One reason for it would be the linker error one would get for using this class in a non-MFC Project.

2. Need to use a CString? Convert to TCHAR!

CString is a string wrapper for TCHAR strings. In doing so, it came with a good number of helpful member methods. However, the implementation of this class in MSVC 6.0 was such that if a programmer needed to make use of the utility member methods, he would need to convert his string data type to TCHAR - back and forth.

This "restriction" automatically excluded programmers using ANSI strings (char*) in UNICODE builds from using this class, and ditto for those using UNICODE strings (WCHAR*) in non-UNICODE builds from using this class - as in both these cases, the strings in question aren't TCHAR strings - the type that CString wraps.

What makes CString of today "flexible" and actually more "likeable"?

1. Use it in any project type - even in a console application!

Yes... All the programmer needs to do is to include the following header -
#include <atlstr.h>
2. Don't change your String Type to suit CString! Choose the right CString instead!

With Visual Studio 7.x and better, CString is actually a specialization of template Class CStringT for type T as TCHAR.

Additionally, there exist two useful specializations of CStringT -
  1. CStringA that specializes CStringT for type char, and
  2. CStringW that specilizes CStringT for type wchar_t.
Hence, CString is actually CStringA for a non-UNICODE build and is a CStringW for a UNICODE build.

The existence of CStringA and CStringW gives the programmer, the flexibility to use the utility member methods supplied by CStringT even when their strings aren't of type - TCHAR.