在同步调用中ReadFile中lpNumberOfBytesRead参数有用吗?
函数原型:
BOOL ReadFile(
HANDLE hFile, // handle to file
LPVOID lpBuffer, // data buffer
DWORD nNumberOfBytesToRead, // number of bytes to read
LPDWORD lpNumberOfBytesRead, // number of bytes read
LPOVERLAPPED lpOverlapped // overlapped buffer
);
我想读一个比较大的文件,每次调用完读函数ReadFile的时候用判断lpNumberOfBytesRead是否和nNumberOfBytesToRead
相等吗?换句话说,调用ReadFile时会出现lpNumberOfBytesRead和nNumberOfBytesToRead不相等的情况吗?在实际情况中,
我发现只要文件够长,ReadFile总会读完指定的长度。哪微软设计pNumberOfBytesRead参数有什么用啊?