MFC Library Reference
TRACE
Sends the specified string to the debugger of the current application.
TRACE(exp ) TRACE(DWORD category, UINT level, LPCSTR lpszFormat, ... )
Remarks
See ATLTRACE2 for a description of TRACE. TRACE and ATLTRACE2 have the same behavior.
This macro is available only in the debug version of MFC.
For more information, see Debugging MFC Applications.