std::char_traits<char>:: eof, std::char_traits<wchar_t>:: eof, std::char_traits<char8_t>:: eof, std::char_traits<char16_t>:: eof, std::char_traits<char32_t>:: eof

From cppreference.com
static int_type eof ( ) ;
(constexpr since C++11)
(noexcept since C++11)

Returns a value not equivalent to any valid value of type char_type .

See CharTraits for the general requirements on character traits for X::eof .

Parameters

(none)

Return value

char_type eof ( )
char EOF
wchar_t WEOF
char8_t an implementation-defined constant that
cannot appear as a valid UTF-8 code unit
char16_t an implementation-defined constant that
cannot appear as a valid UTF-16 code unit
char32_t an implementation-defined constant that
cannot appear as a Unicode code point

Complexity

Constant.

See also

[static]
checks whether a character is eof value
(public static member function)