получить строку от пользователя с редактированием (get a line from a user with editing)
Возвращаемое значение (Return value)
readline returns the text of the line read. A blank line returns
the empty string. If EOF is encountered while reading a line,
and the line is empty, NULL is returned. If an EOF is read with
a non-empty line, it is treated as a newline.
