What is `CString`?

Question

Why do I see some code using CStrings declared differently.

Some use this format

char a_c_string []; 

While others use

CString another_c_string; 

Is there a difference? All the references I have found on CStrings declare it as I did in the first example, I have only seen it done the other way on forums and the like where people are giving examples.

Answer 1

CString is neither a C nor a C++ type. It appears to be a Microsoft invention that is essentially an alternative to std::string:

• CString objects can grow as a result of concatenation operations.
• CString objects follow "value semantics." Think of a CString object as an actual string, not as a pointer to a string.
• You can freely substitute CString objects for const char* and LPCTSTR function arguments.
• A conversion operator gives direct access to the string's characters as a read-only array of characters (a C-style string).

I recommend ignoring it, so that:

(a) people know what you are talking about;
(b) your code is portable;
(c) you are writing C++ that everybody can rationalise about according to the worldwide-accepted ISO C++ standard that many, many people spend many, many hours arguing about for this express purpose (y'know, as opposed to a few guys in a room in one company's office).

It will only be available when you are programming with Microsoft Visual C++, which is substantially limiting.

Answer 2

Many GUI frameworks have their own string class. e.g. QT has the QString, wxWindows has wxString. In this case MFC has the CString. It's then convenient and makes sense to use CString when in the context of MFC gui code because then you're already heavily dependent on Visual C++ and code portability will not be envisaged. I'd be careful of blanket statements saying to ignore it because it's non-standard - it all depends on the context.