哪里错了呀，初学

CTime tmx=CTime::GetCurrentTime();
CString str=tmx.Format("%Y-%m=%d");
int t=tmx.GetDay();
cout<<t<<endl;//怎么不正确

光看代码没有错啊

CTime tmx=CTime::GetCurrentTime();//错误 1 error C2065: “CTime”: 未声明的标识符 c:\documents and settings\administrator\my documents\visual studio 2010\projects\a\a\aa.cpp 27 1 a
//、、错误 2 error C2146: 语法错误: 缺少“;”(在标识符“tmx”的前面) c:\documents and settings\administrator\my documents\visual studio 2010\projects\a\a\aa.cpp 27 1 a

CString str=tmx.Format("%Y-%m=%d");
int t=tmx.GetDay();
cout<<t<<endl;//怎么不正确错误 1 error C2065: “CTime”: 未声明的标识符 c:\documents and settings\administrator\my documents\visual studio 2010\projects\a\a\aa.cpp 27 1 a