How do I convert an ATL/MFC CString to a QString?

Question

Given the encoding of the project is probably Unicode (but not for sure) what is the best way of converting ATL::CString to QString?

What I have thought of is this:

CString c(_T("SOME_TEXT"));
//...
std::basic_string<TCHAR> intermediate((LPCTSTR)c);
QString q;

#ifdef _UNICODE 
q = QString::fromStdWString(intermediate);
#else
q = QString::fromStdString(intermediate);
#endif

Do you think that it works? Any other ideas?

Answer 1

You don't need the intermediate conversion to a std::string . The CString class can be treated as a simple C-style string; that is, an array of characters. All you have to do is cast it to an LPCTSTR .

And once you have that, you just need to create the QString object depending on whether the characters in your CString are of type char or wchar_t . For the former, you can use one of the standard constructors for QString , and for the latter, you can use the fromWCharArray function .

Something like the following code (untested, I don't have Qt installed anymore):

CString c(_T("SOME_TEXT"));
QString q;

#ifdef _UNICODE 
q = QString::fromWCharArray((LPCTSTR)c, c.GetLength());
#else
q = QString((LPCTSTR)c);
#endif

Edit: As suggested in the comments, you have to disable "Treat wchar_t as a built-in type` in your project's Properties to get the above code to link correctly in Visual Studio ( source ).

For _UNICODE , I believe you could also use the fromUtf16 function :

CString c(_T("SOME TEXT"));
QString q = QString::fromUtf16(c.GetBuffer(), c.GetLength());