std::atomic_flag_clear, std::atomic_flag_clear_explicit
Defined in header <atomic> | ||
|---|---|---|
void atomic_flag_clear( volatile std::atomic_flag* obj ) noexcept; | (1) | (since C++11) |
void atomic_flag_clear( std::atomic_flag* obj ) noexcept; | (2) | (since C++11) |
void atomic_flag_clear_explicit( volatile std::atomic_flag* obj,
std::memory_order order ) noexcept;
| (3) | (since C++11) |
void atomic_flag_clear_explicit( std::atomic_flag* obj,
std::memory_order order ) noexcept;
| (4) | (since C++11) |
Atomically changes the state of the std::atomic_flag pointed to by obj to clear (false).
1,2) The memory synchronization ordering is
std::memory_order_seq_cst.
3,4) The memory synchronization ordering is
order.
If
order is one of std::memory_order_consume, std::memory_order_acquire and std::memory_order_acq_rel, the behavior is undefined.Parameters
| obj | - | pointer to std::atomic_flag to access |
| order | - | the memory synchronization ordering |
Notes
std::atomic_flag_clear and std::atomic_flag_clear_explicit can be implemented as obj->clear() and obj->clear(order) respectively.
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2138 | C++11 |
order could be std::memory_order_consume | the behavior is undefined in this case |
See also
|
(C++11) | the lock-free boolean atomic type (class) |
|
(C++11)(C++11) | atomically sets the flag to true and returns its previous value (function) |
|
(C++11) | defines memory ordering constraints for the given atomic operation (enum) |
C documentation for atomic_flag_clear, atomic_flag_clear_explicit |
|
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