C++ Convert string (or char*) to wstring (or wchar_t*)

Question

string s = \"おはよう\";
wstring ws = FUNCTION(s, ws);

How would i assign the contents of s to ws?

Searched google and used some techniques but

Answer 1

From char* to wstring:

char* str = "hello worlffffd";
wstring wstr (str, str+strlen(str));

From string to wstring:

string str = "hello worlffffd";
wstring wstr (str.begin(), str.end());

Note this only works well if the string being converted contains only ASCII characters.