public member function
<ios> <iostream>
Check whether failbit or badbit is set
Returns true if either (or both) the failbit or the badbit error state flags is set for the stream.
At least one of these flags is set when an error occurs during an input operation.
failbit is generally set by an operation when the error is related to the internal logic of the operation itself, and further operations on the stream may be possible. While badbit is generally 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. badbit can be checked independently by calling member function bad:
iostate value
(member constants) | indicates | functions to check state flags |
|---|
| good() | eof() | fail() | bad() | rdstate() |
|---|
| goodbit | No errors (zero value iostate) | true | false | false | false | goodbit |
|---|
| eofbit | End-of-File reached on input operation | false | true | false | false | eofbit |
|---|
| failbit | Logical error on i/o operation | false | false | true | false | failbit |
|---|
| badbit | Read/writing error on i/o operation | false | false | true | true | badbit |
|---|
eofbit, failbit and badbit are member constants with implementation-defined values that can be combined (as if with the bitwise OR operator).
goodbit is zero, indicating that none of the other bits is set.
Note that failing to read due to reaching the End-of-File sets both the eofbit and the failbit.
This function is a synonym of basic_ios::operator!.
Return Value
true if badbit and/or failbit are set.
false otherwise.
Data races
Accesses the stream object.
Concurrent access to the same stream object may cause data races.
Exception safety
Strong guarantee: if an exception is thrown, there are no changes in the stream.