Boost C++ 库

...世界上备受推崇且设计精湛的 C++ 库项目之一。 — Herb Sutter 和 Andrei Alexandrescu, C++ Coding Standards

windows::basic_overlapped_handle::is_open - Boost C++ 函数库

windows::basic_overlapped_handle::is_open

确定句柄是否已打开。

bool is_open() const;