Using WCHAR in a Win32 Dll

The problem is the syntax for a string literal. The type WCHAR is the character type wchar_t; the string literal for this type should be prefixed with "L":

WCHAR string[] = L"MyWideCharString";

[EDIT]
You can also use portable declaration style:

_TCHAR string[] = _T("MyWideCharString");

Here, _TCHAR and _T are just macro which works depending the definition of _UNICODE. They make type declaration either char or w_char and the string literal either L-prefixed or not, which allows you to switch from non-Unicode (ANSI) to Unicode version of the same code. This way, the type declarations and string literal using the macro remain consistent in either case.

See http://msdn.microsoft.com/en-us/library/dybsewaf(v=VS.100).aspx[^].

Null-terminated portable string types based on _TCHAR are LPTSTR and LPCTSTR, see
http://stackoverflow.com/questions/321413/lpcstr-lpctstr-and-lptstr[^].

—SA