ATOMIC_FLAG_INIT
From cppreference.com
Defined in header <atomic>
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#define ATOMIC_FLAG_INIT /* implementation-defined */ |
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Defines the expression which can be used to initialize std::atomic_flag to clear (false) state with the statement std::atomic_flag v = ATOMIC_FLAG_INIT;. It is unspecified if it can be used with other initialization contexts.
If the flag has static storage duration, this initialization is static.
This is the only way to initialize std::atomic_flag to a definite value: the value held after any other initialization is unspecified.
Example
Run this code
#include <atomic> std::atomic_flag static_flag = ATOMIC_FLAG_INIT; // static initialization, // guaranteed to be available during dynamic initialization of static objects. int main() { std::atomic_flag automatic_flag = ATOMIC_FLAG_INIT; // guaranteed to work // std::atomic_flag another_flag(ATOMIC_FLAG_INIT); // unspecified }
See also
(C++11) |
the lock-free boolean atomic type (class) |