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std:: once_flag

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定义于头文件 <mutex>
class once_flag ;
(C++11 起)

类 std::once_flag 是用于 std::call_once 的辅助结构体。

一个类型为 std::once_flag 的对象被传递给多个对 std::call_once 的调用时，可使这些调用相互协调，从而保证其中只有一个调用能够实际运行至完成。

std::once_flag 既不可复制也不可移动。

目录

成员函数

std::once_flag:: once_flag

constexpr once_flag ( ) noexcept ;

构造一个 once_flag 对象。内部状态被设置为指示尚未调用任何函数。

参数

(无)


参见

(C++11)
即使被多个线程调用也仅执行函数一次
(函数模板)
C 文档 for once_flag