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Returns whether the shared_future object is currently associated with a shared state or not.
For default-constructed shared_future objects, this function returns false (unless assigned a valid shared_future).
Shared futures obtain valid shared states either from a future or shared_future object (on construction or assigning them). Unlike future objects, they retain the same shared state association and validity until destroyed (or assigned).
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>
<future>
classes
-
futureC++11
-
future_errorC++11
-
packaged_taskC++11
-
promiseC++11
-
shared_futureC++11
-
enum classes
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future_errcC++11
-
future_statusC++11
-
launchC++11
-
functions
-
asyncC++11
-
future_categoryC++11
-
shared_future
-
shared_future::~shared_futureC++11
-
shared_future::shared_futureC++11
member functions
-
shared_future::getC++11
-
shared_future::operator=C++11
-
shared_future::validC++11
-
shared_future::waitC++11
-
shared_future::wait_forC++11
-
shared_future::wait_untilC++11
-
- Reference
- <future>
- shared_future
- valid
public member function
<future>
std::shared_future::valid
bool valid() const noexcept;
Check for valid shared state
For default-constructed shared_future objects, this function returns false (unless assigned a valid shared_future).
Shared futures obtain valid shared states either from a future or shared_future object (on construction or assigning them). Unlike future objects, they retain the same shared state association and validity until destroyed (or assigned).
Parameters
noneReturn value
true if the object is associated with a shared state.false otherwise.Data races
The shared_future object is accessed.Exception safety
No-throw guarantee: never throws exceptions.See also
- shared_future::get
- Get value (public member function)
- shared_future::wait
- Wait for ready (public member function)
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Spotted an error? contact us