unit ulist;
interface

type
	P2Clist=^T2Clist;
	T2Clist=record
		key:integer;
		pprev,pnext:p2Clist;
	end;

function createElement2C(key:integer):p2Clist;
procedure addfirstelement2C(var PH:p2Clist; p:p2Clist);
procedure addlastelement2C(var PH:p2Clist; p:p2Clist);
procedure InsertElementAfter2C(pEl:p2Clist; p:p2Clist);
procedure InsertElementBefore2C(pEl:p2Clist; p:p2Clist);
function deleteElement2C(pEl:p2Clist):p2Clist;
function deletefirstElement2C(var pH:p2Clist):p2Clist;
procedure disposeList2C(var pH:p2Clist);
function countElements2C(pH:p2Clist):integer;

type
 TlistAction2C=procedure(key:integer);
procedure listAction2CForward(ph:p2Clist; proc:TListAction2C); 
procedure listAction2CBackward(ph:p2Clist; proc:TListAction2C); 
  
implementation

function createElement2C(key:integer):p2Clist;
 begin
 end;
 
procedure addfirstelement2C(var PH:p2Clist; p:p2Clist);
 begin
 end;
 
procedure addlastelement2C(var PH:p2Clist; p:p2Clist);
 begin
 end;
 
procedure InsertElementAfter2C(pEl:p2Clist; p:p2Clist);
 begin
 end;
 
procedure InsertElementBefore2C(pEl:p2Clist; p:p2Clist);
 begin
 end;
 
function deleteElement2C(pEl:p2Clist):p2Clist;
 begin
 end;
 
function deletefirstElement2C(var pH:p2Clist):p2Clist;
 begin
 end;
 
procedure disposeList2C(var pH:p2Clist);
 begin
 end;
 
function countElements2C(pH:p2Clist):integer;
 begin
 end;
 
procedure listAction2CForward(ph:p2Clist; proc:TListAction2C); 
 begin
 end;
 
procedure listAction2CBackward(ph:p2Clist; proc:TListAction2C); 
 begin
 end;

end.