c++ RegSetValueEx sets only one char value in registry - c++

Question

I'm casting (char * ) on data and i'm getting only one char value in the registry. if
i don't use the casting msvc 2010 tells me that the argument type LPCTSTR is incompatible with const char *.
can someone help me?
HKEY hKey;
LPCTSTR sk = TEXT("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run");
LONG openRes = RegOpenKeyEx(HKEY_CURRENT_USER, sk, 0, KEY_ALL_ACCESS , &hKey);
if (openRes==ERROR_SUCCESS) {
printf("Success opening key.");
} else {
printf("Error opening key.");
}
LPCTSTR value = TEXT("SomeKey");
LPCTSTR data = L"TestData\0";
LONG setRes = RegSetValueEx (hKey, value, 0, REG_SZ, (LPBYTE)data, strlen(data)+1);
if (setRes == ERROR_SUCCESS) {
printf("Success writing to Registry.");
} else {
printf("Error writing to Registry.");
}
cout << setRes << endl;
LONG closeOut = RegCloseKey(hKey);
if (closeOut == ERROR_SUCCESS) {
printf("Success closing key.");
} else {
printf("Error closing key.");
}

Answer 1

strlen(data) is probably returning a value of 1, as strlen expects a char* and L"TestData\0" is wide. Use TEXT("TestData\0") and call _tcslen(data).
Note that RegSetValueEx expects the sizeof the data, so use _tcslen(data) * sizeof(TCHAR)

Answer 2

Where are you casting data?
Either way, it looks like you may be working with wide characters, but you seem to be using "plain old" strlen - instead of wcslen or some other function intended to work with wide-character strings.

Answer 3

replace the L"TestData" by _T("TestData"); and strlen(data)+1 by tcslen(data) * sizeof(TCHAR));
so your code looks like this :
LPCTSTR value = TEXT("SomeKey");
LPCTSTR data = TEXT("TestData");
LONG setRes = RegSetValueEx(hKey, value, 0, REG_SZ, (LPBYTE)data, _tcslen(data) * sizeof(TCHAR));