RegSetValueEx Only shows writes first character

Question

In the following code, RegSetValueEx is only writing the first letter of my string. I've tried changing the sizes to just about anything I can think of, and I only ever get the first string. Any help is appreciated.

LPCWSTR path = L"Test String";
size_t size = wclsen(path) * sizeof(wchar_t);

DWORD dwResult = RegSetValueEx(HKEY_LOCAL_MACHINE,
                            "SOFTWARE\\My App",
                            0,
                            REG_SZ,
                            (LPBYTE)path,
                            test);

I've tried using path.size() * sizeof(wchar_t) and any number of other sizes I could think of, but nothing seems to work right. Any ideas?

Answer 1

RegSetValueEx() expects REG_SZ data to be provided as const TCHAR*, which in your case is const CHAR* per your compiler settings - as evident by the fact that you are able to pass a char* to the second parameter, which means you are actually calling RegSetValueExA(). Since you are providing a const WCHAR* to RegSetValueExA(), the first 0x00 byte gets interpreted as a null terminator, hence only a single character value gets written.

Your options are:

1. RegSetValueExW(..., (const BYTE*) path, ...

2. CString sPath(path); RegSetValueEx(..., (const BYTE*) (LPCTSTR) sPath, ...

3. Switch project settings to Unicode build

Answer 2

Sounds like you haven't defined UNICODE/_UNICODE before compiling, so the zero-byte in your wide string is being interpreted as signaling the end of the string.

Try using RegSetValueExW (and L"SOFTWARE\\My App") instead.