if you use CFile Class, try CFile::Seek(-1,CFile::current)

try ??????????*.dll

Anyway,thanks a lot for your replies.

Erverthing is ok today! I don't know why

I derived a new class named CMySocket from CSocket. Then generate another class named CCollectorInfo (in order to store the information of Collector),I defined a CMySocket pointer in this class. Already included the header file of CMySocket I got error messages as follow: --------------------Configuration: SaroTransfer - Win32 Debug-------------------- Compiling... MySocket.cpp c:\documents and settings\administrator\×ÀÃæ\sarotransfer\collectorinfo.h(22) : error C2143: syntax error : missing ';' before '*' c:\documents and settings\administrator\×ÀÃæ\sarotransfer\collectorinfo.h(22) : error C2501: 'CMySocket' : missing storage-class or type specifiers c:\documents and settings\administrator\×ÀÃæ\sarotransfer\collectorinfo.h(22) : error C2501: 'pSocket' : missing storage-class or type specifiers Error executing cl.exe. SaroTransfer.exe - 3 error(s), 0 warning(s) Thanks of any help!