From: gvision@ntlworld.com   
      
    wrote in message   
   news:ogvur0t6iidgaf3ipeb1rnu5vje5beh6h5@4ax.com...   
   > Hi,   
   >   
   > I understand the use of the ^ in pointers and how pointers work in   
   > TP7. I recently came accross soem code where they haev for example:   
   >   
   > T^^.next   
   >   
   > I have used it in the form of T^.next when traversing a linked list.   
   > Am just not sure how the double carets are to be used.   
      
   It simply means that T is a pointer to pointer, and double-dereferencing is   
   indeed often used by linked-list code. For example:   
      
   type   
     PDirectory = ^TDirectory;   
     TDirectory = object   
       Next: PDirectory;   
       Children: PDirectory;   
       ....;   
     end;   
      
    function  TDirectory.AddChild(D: PDirectory): Boolean;   
    var   
      PCur: ^PDirectory;   
    begin   
      if D = nil then   
      begin   
        AddChild := False;   
        Exit;   
      end;   
      PCur := @Children;   
      while (PCur^ <> nil) and (DosCompare(D^.Name^, PCur^^.Name^) = 1) do   
        PCur := @PCur^^.Next;   
      D^.Next := PCur^;   
      PCur^ := D;   
      AddChild := True;   
    end;   
      
   Note that the intial value for PCur is set to the address of the pointer   
   that contains the address of the first in the linked-list of Children. The   
   use of double-dereferencing here ellimitates the need to handle the   
   otherwise special case of dealing with the first element of the list.   
      
   > Also I have seen @ being used instead of NEW,   
      
   No you haven't. New allocates heap memory to an object and returns a pointer   
   to it. @ returns the address of an existing object.   
      
   --   
   Jay   
      
   Author of Graphic Vision   
   http://homepage.ntlworld.com/gvision/   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)