lpOverlapped
lpOverlapped is a common name used in Windows API programming to refer to a pointer to an OVERLAPPED structure, i.e., LPOVERLAPPED. This pointer is used to support asynchronous (overlapped) input/output operations in many file and device I/O functions, such as ReadFile, WriteFile, ReadFileEx, and WriteFileEx. The lpOverlapped parameter allows a caller to initiate an I/O operation without blocking the calling thread and to obtain completion status later.
The OVERLAPPED structure contains fields that the system uses to track and complete the asynchronous operation.
In typical usage, a function may return immediately with ERROR_IO_PENDING if the operation is initiated asynchronously.
See also: OVERLAPPED, LPOVERLAPPED, ReadFile, WriteFile, GetOverlappedResult, Io completion ports.