NAME¶

std::atomic::atomic - std::atomic::atomic

Synopsis¶

(since
atomic() noexcept = default; C++11)
(until
C++20)
constexpr atomic() (1) (since
noexcept(std::is_nothrow_default_constructible_v<T>); C++20)
constexpr atomic( T desired ) noexcept; (2) (since
C++11)
atomic( const atomic& ) = delete; (3) (since
C++11)

Constructs a new atomic variable.

1) The default constructor is trivial: no initialization takes place
other than zero initialization of static and thread-local objects. (until C++20)
std::atomic_init may be used to complete initialization.
1) Value-initializes the underlying object (i.e. with T()). The
initialization is not atomic. (since C++20)
The program is ill-formed if std::is_default_constructible_v<T> is
false.

2) Initializes the underlying object with desired. The initialization is not atomic.
3) Atomic variables are not CopyConstructible.

Parameters¶

desired - value to initialize with

Notes¶

The default-initialized std::atomic<T> does not contain a T object,
and its only valid uses are destruction and initialization by (until C++20)
std::atomic_init, see LWG issue 2334.