基本内容

ReadFileEx

说明

与ReadFile相似，只是它只能用于异步读取文件操作，异步操作完成后会调用指定的回调函数

返回值

返回非零表示成功，返回零表示失败，并可用GetLastError得到错误代码

Windows版本：Windows XP / Windows Vista / Windows 7

Windows 2000 Server / Windows Server 2003 / Windows Server 2008

DLL依赖：kernel32.dll

C中声明

BOOL ReadFileEx(

HANDLE hFile, //文件的句柄

LPVOID lpBuffer, //用于接收数据的缓冲区

DWORD nNumberOfByteToRead, //允许接收的最大字节数

LPOVERLAPPED lpOverlapped, //一个OVERLAPPED结构的指针

LPOVERLAPPED_COMPLETION_ROUTINE lpCompletionRoutine //异步读取完成后调用的回调函数

);

VB中的声明

Declare Function ReadFileEx Lib "kernel32" Alias "ReadFileEx" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToRead As Long, lpOverlapped As OVERLAPPED, ByVal lpCompletionRoutine As Long) As Long