ATOMIC_VAR_INIT
From cppreference.com
| Defined in header <atomic>
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| #define ATOMIC_VAR_INIT(value) /* implementation-defined */ |
(since C++11) (deprecated in C++20) |
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Expands to an expression which can be used to initialize an std::atomic object that can be initialized from value. If the atomic object has static storage duration, this initialization is constant initialization.
[edit] Notes
Accessing the variable during initialization from another thread, even through an atomic operation, is a data race (it may happen if the address is immediately passed to another thread with a std::memory_order_relaxed operation)
This macro is primarily provided for compatibility with C; it behaves the same as the constructor of std::atomic.
[edit] Example
Run this code
#include <atomic> #include <iostream> int main() { std::atomic<int> a = ATOMIC_VAR_INIT(1); // std::atomic<int> a(1); // C++-only alternative std::cout << "Initialized std::atomic<int> as: " << a << '\n'; }
Output:
Initialized std::atomic<int> as: 1
[edit] See also
| (C++11)(deprecated in C++20) |
non-atomic initialization of a default-constructed atomic object (function template) |
| constructs an atomic object (public member function of std::atomic<T>)
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| C documentation for ATOMIC_VAR_INIT
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