character literal in C++
There are five kinds of character literals: * Ordinary character literals of type char, for example 'a' * UTF-8 character literals of type char (char8_t in C++20), for example u8'a' * Wide-character literals of type wchar_t, for example L'a' * UTF-16 character literals of type char16_t, for example u'a' * UTF-32 character literals of type char32_t, for example U'a'