Need some help with #define

Question

In the #define what does the L mean ?

#define NT_DEVICE_NAME      L"\\Device\\SIOCTL"

Answer 1

It means that the string is a unicode (UTF-16) encoded string. A UTF-16 string is a sequence of 16 bit words, rather than 8 bit characters. Windows's native format for strings is UTF-16. See here for more information about unicode: http://www.unicode.org/

Answer 2

That the string should be of type wchar_t[].