- check if a state is ok
while(cin >> word)
// ok: read successful
-
condition states are constants defined in
ios_baseas public membersios_base::badbit: corrupted.- set when the error involves the loss of integrity of the stream, which is likely to persist even if a different operation is attempted on the stream.
- indicates a system-level failure, such as an unrecoverable read or write error.
- usually not possible to use a stream once badbit has been set.
ios_base::failbit: failed.- set by an operation when the error is related to the internal logic of the operation itself; further operations on the stream may be possible.
- is set after a recoverable error, such as reading a character when numeric data was expected.
- often possible to correct such problems and continue using the stream.
ios_base::eofbit: hit end-of-file.ios_base::goodbit: not in an error state.- indicating none of the other bits is set.
-
Note
- At least one of
failbitandbadbitis set when an error occured during an input operation. - Failing to read due to reaching the end-of-file sets both
eofbitandfailbit. fail()is a synonym ofios::operator!
- At least one of
-
checks
s.bad():eofbitis set.s.fail():failbitorbadbitis set.s.eof():eofis set.s.good(): none of above three states is set.s.is_open():s.clear(): reset all condition values in the stream to valid state.
-
operation on flags
- retrieve :
basic_ios::rdstate - set :
basic_ios::setstate
- retrieve :
-
about types:
std::ios_base::iostateis type for stream error state flags
References: