std::atomic_ref<T>::operator++,++(int),--,--(int)
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std::atomic_ref
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atomic_ref::operator++atomic_ref::operator++(int)atomic_ref::operator--atomic_ref::operator--(int)
Provided only when
T is an integral type other than cv bool or a pointer-to-object typevalue_type operator++() const noexcept;
(1)
(since C++20)
value_type operator++( int ) const noexcept;
(2)
(since C++20)
value_type operator--() const noexcept;
(3)
(since C++20)
value_type operator--( int ) const noexcept;
(4)
(since C++20)
Atomically increments or decrements the current value of the referenced object. These operations are read-modify-write operations.
1) Performs atomic pre-increment. Equivalent to return fetch_add(1) + 1;.
2) Performs atomic post-increment. Equivalent to return fetch_add(1);.
3) Performs atomic pre-decrement. Equivalent to return fetch_sub(1) - 1;
4) Performs atomic post-decrement. Equivalent to return fetch_sub(1);.
- For signed integral types, arithmetic is defined to use two’s complement representation. There are no undefined results.
- For pointer-to-object types, the result may be an undefined address, but the operations otherwise have no undefined behavior. The program is ill-formed if std::remove_pointer_t <T> is not a complete object type.
These overloads participate in overload resolution only if std::is_const_v <T> is false.
Contents
[edit] Return value
1,3) The value of the referenced object after the modification.
2,4) The value of the referenced object before the modification.
[edit] Notes
Unlike most pre-increment and pre-decrement operators, the pre-increment and pre-decrement operators for atomic_ref do not return a reference to the modified object. They return a copy of the stored value instead.
[edit] 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 3508 (P3323R1) |
C++20 | increment and decrement operators were meaningless for const T | constrained to accept only non-const T
|
[edit] See also
atomically adds the argument to the value stored in the referenced object and obtains the value held previously
(public member function) [edit]
(public member function) [edit]
atomically subtracts the argument from the value stored in the referenced object and obtains the value held previously
(public member function) [edit]
(public member function) [edit]