void clear( int nState = 0 );
nState
If 0, all error bits are cleared; otherwise bits are set according to the following masks (ios enumerators) that can be combined using the bitwise-OR (|) operator:
| Value | Meaning |
| ios::goodbit | No error condition (no bits set) |
| ios::eofbit | End of file reached |
| ios::failbit | A possibly recoverable formatting or conversion error |
| ios::badbit | A severe I/O error |
Sets or clears the error-state flags. The rdstate function can be used to read the current error state.