小弟刚学VC 大家帮忙看看这个问题

void CDialogDlg::OnDblClickCalendar1() 
{
// TODO: Add your control notification handler code here
CString  cSelectedDate;
char*    cDay=" ";
char*    cYear=" ";
itoa(m_Calendar1.GetDay(),cDay,10);
cSelectedDate=cDay;
switch(m_Calendar1.GetMonth())
{
case 1:
cSelectedDate=cSelectedDate+"January";
break;
    case 2:
cSelectedDate=cSelectedDate+"February";
break;
case 3:
cSelectedDate=cSelectedDate+"March";
break;
case 4:
cSelectedDate=cSelectedDate+"Aprial";
break;
case 5:
cSelectedDate=cSelectedDate+"May";
break;
case 6:
cSelectedDate=cSelectedDate+"June";
break;
case 7:
cSelectedDate=cSelectedDate+"July";
break;
case 8:
cSelectedDate=cSelectedDate+"August";
break;
case 9:
cSelectedDate=cSelectedDate+"September";
break;
case 10:
cSelectedDate=cSelectedDate+"October";
break;
case 11:
cSelectedDate=cSelectedDate+"November";
break;
case 12:
cSelectedDate=cSelectedDate+"December";
break;
}
itoa(m_Calendar1.GetYear(),cYear,10);
cSelectedDate=cSelectedDate+cYear;
AfxMessageBox("You double-clicked on:"+cSelectedDate,MB_OK|
MB_INFORMATION,0);
}
下面是错误的信息---------------Configuration: Dialog - Win32 Debug--------------------
Compiling...
DialogDlg.cpp
D:\111\Dialog\DialogDlg.cpp(229) : error C2065: 'MB_INFORMATION' : undeclared identifier
执行 cl.exe 时出错.Dialog.exe - 1 error(s), 0 warning(s)大家帮帮小弟啊  先谢谢了