good() Returns true if the stream is OK (goodbit is “set”)
eof() Returns true if end-of-file was hit (eofbit is set)
fail() Returns true if an error has occurred (failbit or badbit is set)
bad() Returns true if a fatal error has occurred (badbit is set)
rdstate() Returns the currently set flags
clear() Clears all flags
clear(state) Clears all and sets state flags
setstate(state) Sets additional state flags