codice:
 #include <windows.h>

 DWORD GetFileDimension( LPCSTR szFileName )
 {
   HANDLE hFile;
   DWORD  dwSize;

   hFile = CreateFile( szFileName, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL );

   if ( !hFile )
     return ( -1 );


   dwSize = GetFileSize( hFile, NULL );
   CloseHandle( hFile );

   return ( dwSize );
 }



 ....

 GetFileDimension( "C:\\WINDOWS\\file.ext" );