std::atomic_ref<T>:: operator+=,-=
|
|
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| Member functions | ||||
|
(C++26)
|
||||
|
Operations for arithmetic types
(except
bool
and pointer-to-object)
|
||||
|
atomic_ref::operator+=
atomic_ref::operator-=
|
||||
|
Operations for integral types
(except
bool
and pointer-to-object)
|
||||
|
(C++26)
|
||||
|
(C++26)
|
||||
|
Operations for integral types
(except
bool
)
|
||||
| Constants | ||||
|
Provided only when
T
is an arithmetic type other than
cv
bool
or a pointer-to-object type
|
||
|
value_type operator
+
=
(
difference_type arg
)
const
noexcept
;
|
(1) | (constexpr since C++26) |
|
value_type operator
-
=
(
difference_type arg
)
const
noexcept
;
|
(2) | (constexpr since C++26) |
Atomically replaces the current value referenced by
*
ptr
with the result of computation involving the previous value and
arg
. These operations are read-modify-write operations.
- For signed integral types, arithmetic is defined to use two’s complement representation. There are no undefined results.
- For floating-point types, the floating-point environment in effect may be different from the calling thread's floating-point environment. The operation need not be conform to the corresponding std::numeric_limits traits but is encouraged to do so. If the result is not a representable value for its type, the result is unspecified but the operation otherwise has no undefined behavior.
-
For pointer types, the result may be an undefined address, but the operation otherwise has no undefined behavior.
- If std:: remove_pointer_t < T > is not a complete object type, the program is ill-formed.
These overloads participate in overload resolution only if std:: is_const_v < T > is false .
Contents |
Parameters
| arg | - | the argument for the arithmetic operation |
Return value
The resulting value (that is, the result of applying the corresponding binary operator to the value referenced by
*
ptr
immediately preceding the effects of the corresponding member function).
Notes
Unlike most compound assignment operators, the compound assignment operators for
atomic_ref
return a copy of the stored value instead of a reference to
arg
.
Example
|
This section is incomplete
Reason: no example |
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 | compound assignment operators were meaningless for const T |
constrained to accept only non-const
T
|
See also
|
atomically adds the argument to the value stored in the referenced object and obtains the value held previously
(public member function) |
|
|
atomically subtracts the argument from the value stored in the referenced object and obtains the value held previously
(public member function) |
|
|
atomically increments or decrements the referenced object by one
(public member function) |
|
|
atomically performs bitwise AND, OR, XOR with the referenced value
(public member function) |