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std::atomic_fetch_max, std::atomic_fetch_max_explicit - cppreference.com

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Defined in header <atomic>

template< class T > T atomic_fetch_max( std::atomic<T>* obj, typename std::atomic<T>::value_type arg ) noexcept;

 (1) (since C++26)

template< class T > T atomic_fetch_max( volatile std::atomic<T>* obj, typename std::atomic<T>::value_type arg ) noexcept;

 (2) (since C++26)

template< class T > T atomic_fetch_max_explicit( std::atomic<T>* obj, typename std::atomic<T>::value_type arg, std::memory_order order ) noexcept;

 (3) (since C++26)

template< class T > T atomic_fetch_max_explicit( volatile std::atomic<T>* obj, typename std::atomic<T>::value_type arg, std::memory_order order ) noexcept;

 (4) (since C++26)

Atomically replaces the value pointed by obj with the result of std::max between the old value of obj and arg. Returns the value obj held previously. The operation is performed as if the following was executed:

1,2) obj->fetch_max(arg)

3,4) obj->fetch_max(arg, order)

If std::atomic<T> has no fetch_max member (this member is only provided for integral and pointer types except bool), the program is ill-formed.

Parameters

obj - pointer to the atomic object to modify
arg - the value to std::max with the value stored in the atomic object
order - the memory synchronization ordering

Return value

The value immediately preceding the effects of this function in the modification order of *obj.

Notes

Feature-test macro Value Std Feature
__cpp_lib_atomic_min_max 202403L (C++26) Atomic minimum/maximum

Example

See also

atomically performs std::max between the argument and the value of the atomic object and obtains the value held previously
(public member function of std::atomic<T>) [edit]
replaces the atomic object with the result of std::min with a non-atomic argument and obtains the previous value of the atomic
(function template) [edit]