basic_istream& unget();
The unformatted input function puts back the previous element in the stream, if possible, as if by calling
rdbuf()->
sungetc
()
. If rdbuf
()
is a null pointer, or if the call to sungetc
returns T::
eof
()
, the function calls
setstate
(badbit)
. In any case, it returns *this
.