VC向文件追加数据

CFile::SeekToEnd

CFile::Write

之前一直用的是CFile::modeCreate|CFile::modeReadWrite，今天才发现，If the file exists already, it is truncated to 0 length(也就是，如果文件存在，会将其截断成0字节)，需要再加上CFile::modeNoTruncate——If the file being created already exists, it is not truncated to 0 length.