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Sets a new value for the stream's internal error state flags.
The current value of the flags is overwritten: All bits are replaced by those in state; If state is goodbit (which is zero) all error flags are cleared.
In the case that no stream buffer is associated with the stream when this function is called, the badbit flag is automatically set (no matter the value for that bit passed in argument state).
Note that changing the state may throw an exception, depending on the latest settings passed to member exceptions.
The current state can be obtained with member function rdstate.
In this example,
Concurrent access to the same stream object may cause data races.
It throws an exception of member type failure if the resulting error state flag is not goodbit and member exceptions was set throw for that state.
Reference
C library:
- <cassert> (assert.h)
- <cctype> (ctype.h)
- <cerrno> (errno.h)
-
<cfenv> (fenv.h)C++11
- <cfloat> (float.h)
-
<cinttypes> (inttypes.h)C++11
- <ciso646> (iso646.h)
- <climits> (limits.h)
- <clocale> (locale.h)
- <cmath> (math.h)
- <csetjmp> (setjmp.h)
- <csignal> (signal.h)
- <cstdarg> (stdarg.h)
-
<cstdbool> (stdbool.h)C++11
- <cstddef> (stddef.h)
-
<cstdint> (stdint.h)C++11
- <cstdio> (stdio.h)
- <cstdlib> (stdlib.h)
- <cstring> (string.h)
-
<ctgmath> (tgmath.h)C++11
- <ctime> (time.h)
-
<cuchar> (uchar.h)C++11
- <cwchar> (wchar.h)
- <cwctype> (wctype.h)
Containers:
-
<array>C++11
- <deque>
-
<forward_list>C++11
- <list>
- <map>
- <queue>
- <set>
- <stack>
-
<unordered_map>C++11
-
<unordered_set>C++11
- <vector>
-
Input/Output:
Multi-threading:
-
<atomic>C++11
-
<condition_variable>C++11
-
<future>C++11
-
<mutex>C++11
-
<thread>C++11
-
Other:
- <algorithm>
- <bitset>
-
<chrono>C++11
-
<codecvt>C++11
- <complex>
- <exception>
- <functional>
-
<initializer_list>C++11
- <iterator>
- <limits>
- <locale>
- <memory>
- <new>
- <numeric>
-
<random>C++11
-
<ratio>C++11
-
<regex>C++11
- <stdexcept>
- <string>
-
<system_error>C++11
-
<tuple>C++11
-
<type_traits>C++11
-
<typeindex>C++11
- <typeinfo>
- <utility>
- <valarray>
<ios>
types
manipulators
other functions
-
iostream_categoryC++11
-
basic_ios
- basic_ios::~basic_ios
- basic_ios::basic_ios
public members
- basic_ios::bad
- basic_ios::clear
- basic_ios::copyfmt
- basic_ios::eof
- basic_ios::exceptions
- basic_ios::fail
- basic_ios::fill
- basic_ios::good
- basic_ios::imbue
- basic_ios::narrow
- basic_ios::operator bool
- basic_ios::operator!
- basic_ios::rdbuf
- basic_ios::rdstate
- basic_ios::setstate
- basic_ios::tie
- basic_ios::widen
protected members
- basic_ios::init
-
basic_ios::moveC++11
-
basic_ios::set_rdbufC++11
-
basic_ios::swapC++11
public member function
<ios> <iostream>
std::basic_ios::clear
void clear (iostate state = goodbit);
Set error state flags
The current value of the flags is overwritten: All bits are replaced by those in state; If state is goodbit (which is zero) all error flags are cleared.
In the case that no stream buffer is associated with the stream when this function is called, the badbit flag is automatically set (no matter the value for that bit passed in argument state).
Note that changing the state may throw an exception, depending on the latest settings passed to member exceptions.
The current state can be obtained with member function rdstate.
Parameters
- state
- An object of type ios_base::iostate that can take as value any combination of the following state flag member constants:
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
goodbit is zero, indicating that none of the other bits is set.
Return Value
noneExample
|
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In this example,
myfile
is open for input operations, but we perform an output operation on it, so failbit
is set. The example calls then clear in order to remove the flag and allow further operations like getline to be attempted on myfile
.Data races
Modifies the stream object.Concurrent access to the same stream object may cause data races.
Exception safety
Basic guarantee: if an exception is thrown, the stream is in a valid state.It throws an exception of member type failure if the resulting error state flag is not goodbit and member exceptions was set throw for that state.
See also
- basic_ios::fail
- Check whether failbit or badbit is set (public member function)
- basic_ios::good
- Check whether state of stream is good (public member function)
- basic_ios::bad
- Check whether badbit is set (public member function)
- basic_ios::eof
- Check whether eofbit is set (public member function)
- basic_ios::rdstate
- Get error state flags (public member function)
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Spotted an error? contact us