using iostate = T2;
| Element | Effect(s) if set | 
| badbit | indicates a loss of integrity in an input or output sequence
 (such as an irrecoverable read error from a file); | 
| eofbit | indicates that an input operation reached the end of an input sequence; | 
| failbit | indicates that an input operation failed to read the expected characters,
 or that an output operation failed to generate the desired characters. |