What does the prefix L"..." stand for in GCC C without #including wchar?

Question

That is, why does unsigned short var= L'ÿ' work, but unsigned short var[]= L"ÿ"; does not?

Answer 1

L'ÿ' is of type wchar_t, which can be implicitly converted into an unsigned short. L"ÿ" is of type wchar_t[2], which cannot be implicitly converted into unsigned short[2].

Answer 2

L is the prefix for wide character literals and wide-character string literals. This is part of the language and not a header. It's also not GCC-specific. They would be used like so:

wchar_t some_wchar = L'ÿ';
wchar_t *some_wstring = L"ÿ"; // or wchar_t some_wstring[] = L"ÿ";

You can do unsigned short something = L'ÿ'; because a conversion is defined from wchar_t to short. There is not such conversion defined between wchar_t* and short.