string operator "" s(const char* str, size_t len);
Returns: string{str,len}
u16string operator "" s(const char16_t* str, size_t len);
Returns: u16string{str,len}
u32string operator "" s(const char32_t* str, size_t len);
Returns: u32string{str,len}
wstring operator "" s(const wchar_t* str, size_t len);
Returns: wstring{str,len}
[ Note: The same suffix s is used for chrono::duration literals denoting seconds but there is no conflict, since duration suffixes apply to numbers and string literal suffixes apply to character array literals. — end note ]