once_flag Structure

Represents a struct that is used with the template function call_once to ensure that initialization code is called only once, even in the presence of multiple threads of execution.

struct once_flag
{
   constexpr once_flag() noexcept;
   once_flag(const once_flag&);
   once_flag& operator=(const once_flag&);
};

The once_flag struct has only a default constructor.

Objects of type once_flag can be created, but they cannot be copied.

Header: mutex

Namespace: std

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