# std::atomic_ref<T>::operator+=,-=,&=,|=,^=

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< cpp‎ | atomic‎ | atomic ref

member only of `atomic_ref<Integral>` and `atomic_ref<Floating>` template specializations |  |
T operator+=( T arg ) const noexcept; | (1) |
member only of `atomic_ref<T*>` template specialization |  |
T* operator+=( std::ptrdiff_t arg ) const noexcept; | (1) |
member only of `atomic_ref<Integral>` and `atomic_ref<Floating>` template specializations |  |
T operator-=( T arg ) const noexcept; | (1) |
member only of `atomic_ref<T*>` template specialization |  |
T* operator-=( std::ptrdiff_t arg ) const noexcept; | (1) |
member only of `atomic_ref<Integral>` template specialization |  |
T operator&=( T arg ) const noexcept; | (3) |
T operator|=( T arg ) const noexcept; | (4) |
T operator^=( T arg ) const noexcept; | (5) |

Atomically replaces the current value of the referenced object with the result of computation involving the previous value and `arg`. These operations are read-modify-write operations.

1) Performs atomic addition. Equivalent to return fetch_add(arg) + arg;.
2) Performs atomic subtraction. Equivalent to return fetch_sub(arg) - arg;.
3) Performs atomic bitwise and. Equivalent to return fetch_and(arg) & arg;.
4) Performs atomic bitwise or. Equivalent to return fetch_or(arg) | arg;.
5) Performs atomic bitwise exclusive or. Equivalent to return fetch_xor(arg) ^ arg;.

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 `T*` types, the result may be an undefined address, but the operations otherwise have no undefined behavior. The program is ill-formed if `T` is not an object type.

### 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 immediately preceding the effects of the corresponding member function).

### Notes

Unlike most compound assignment operators, the compound assignment operators for `atomic_ref` do not return a reference to their left-hand arguments. They return a copy of the stored value instead.

### See also

operator++operator++(int)operator--operator--(int) | atomically increments or decrements the referenced object by one (public member function)

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