1. // 003_异步IO_扩展版API.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
    2. //
    4. #include <iostream>
    5. #include <windows.h>
    6. #include <stdio.h>
    8. struct MyOverlapped : public OVERLAPPED {
    9.     MyOverlapped()
    10.     {
    11.         // 将OVERLAPPED部分填充为0
    12.         memset(this, 0, sizeof(OVERLAPPED));
    13.         pBuff = NULL;
    14.     }
    15.     char *pBuff;
    16.     ~MyOverlapped() {
    17.         if (pBuff) {
    18.             delete pBuff;
    19.         }
    20.     }
    21. };
    24. VOID WINAPI ioProc(
    25.     _In_    DWORD dwErrorCode,/*错误码,*/
    26.     _In_    DWORD dwNumberOfBytesTransfered,/*实际完成的字节数*/
    27.     _Inout_ LPOVERLAPPED lpOverlapped/*重叠结构体,传入到ReadFile那个*/
    28.     )
    29. {
    30.     MyOverlapped* pOv = (MyOverlapped*)lpOverlapped;
    31.     printf("读取偏移:[%d]的IO任务完成, 实际读取到的字节数:%d"
    32.            "读取到的内容是:%s",
    33.            pOv->Offset,
    34.            pOv->InternalHigh,
    35.            pOv->pBuff);
    36. }
    38. int main()
    39. {
    40.     HANDLE hFile = INVALID_HANDLE_VALUE;
    41.     hFile = CreateFile(
    42.         L"003_异步IO_扩展版API.cpp",
    43.         GENERIC_READ,/*读写方式:只读*/
    44.         FILE_SHARE_READ,/*共享方式: 共享读*/
    45.         NULL,/*安全描述符*/
    46.         OPEN_EXISTING,/*创建标志:存在时才打开*/
    47.         FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,/*文件属性和标志:正常属性|重叠IO标志 */
    48.         NULL);
    50.     MyOverlapped* ov = new MyOverlapped;
    51.     ov->Offset = 0;
    52.     ov->pBuff = new char[100];
    53.     memset(ov->pBuff, 0, 100);
    54.     ov->hEvent = NULL;
    55.     ReadFileEx(hFile, ov->pBuff, 50, ov, ioProc);
    57.     while ( 1 )
    58.     {
    59.         SleepEx(30, TRUE);
    60.     }
    61. }