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std::atomic::fetch_sub(3) C++ Standard Libary std::atomic::fetch_sub(3) NAME std::atomic::fetch_sub - std::atomic::fetch_sub Synopsis member only of atomic<Integral> specializations and atomic<Floating> specializations (since C++20) T fetch_sub( T arg, std::memory_order order = (1) (since C++11) std::memory_order_seq_cst ) noexcept; T fetch_sub( T arg, std::memory_order order = std::memory_order_seq_cst ) volatile (2) (since C++11) noexcept; member only of atomic<T*> partial specialization T* fetch_sub( std::ptrdiff_t arg, std::memory_order order = (3) (since C++11) std::memory_order_seq_cst ) noexcept; T* fetch_sub( std::ptrdiff_t arg, std::memory_order order = (4) (since C++11) std::memory_order_seq_cst ) volatile noexcept; Atomically replaces the current value with the result of arithmetic subtraction of the value and arg. That is, it performs atomic post-decrement. The operation is read-modify-write operation. Memory is affected according to the value of order. 1,2) For signed integral types, arithmetic is defined to use twos 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_lim- its (since C++20) 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. 3,4) The result may be an undefined address, but the operation oth- erwise has no undefined behavior. If T is not a complete object type, the program is ill-formed. It is deprecated if std::atomic<T>::is_always_lock_free is false and (since C++20) overload (2) or (4) participates in overload resolution. Parameters arg - the other argument of arithmetic subtraction order - memory order constraints to enforce Return value The value immediately preceding the effects of this function in the modification order of *this. Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Correct behavior P0558R1 C++11 arithmetic permitted on pointers to (possibly made ill-formed cv-qualified) void or function See also atomic_fetch_sub subtracts a non-atomic value from an atomic object and atomic_fetch_sub_explicit obtains the previous value of the atomic (C++11) (function template) (C++11) operator++ operator++(int) increments or decrements the atomic value by one operator-- (public member function) operator--(int) http://cppreference.com 2024.06.10 std::atomic::fetch_sub(3)
NAME | Synopsis | Parameters | Return value | See also
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