c++ - CreateFile/WriteFile 没有破坏旧文件的内容

Question

旧内容不会被清除。相反，数据正在被覆盖，所以我仍然看到旧内容。我没有做什么？

hFile = CreateFile(fname, // open testfile.txt
    GENERIC_WRITE, // open for reading
    0, // do not share
    NULL, // default security
    OPEN_ALWAYS, // 
    FILE_ATTRIBUTE_NORMAL, // normal file
    NULL); // no attribute template

dwBytesToWrite = buff.GetLength();
WriteFile(hFile, buff.GetBuffer(100), dwBytesToWrite, &dwBytesWritten, NULL);

Answer 1

您为 dwCreationDisposition 指定了错误的值.您需要指定 CREATE_ALWAYS。

Creates a new file, always. If the specified file exists and is writable, the function overwrites the file, the function succeeds, and last-error code is set to ERROR_ALREADY_EXISTS (183). If the specified file does not exist and is a valid path, a new file is created, the function succeeds, and the last-error code is set to zero.