Syntax
' c-char ' (1) u8 ' c-char ' (2) (since C++17) u ' c-char ' (3) (since C++11) U ' c-char ' (4) (since C++11) L ' c-char ' (5) ' c-char-sequence ' (6)
where.
c-char is either a character from the basic source character set minus single-quote ('), backslash (\), or the newline character, escape sequence, as defined in escape sequences universal character name, as defined in escape sequences
c-char-sequence is a sequence of two or more c-cha