{ Renata Lara }
{ CSCI 3333.01 }
{ Feb. 5, 1998 }
{ This program implements List ADT in a linked structure. }
PROGRAM LlistADT;
USES help1380; { Links to file help1380 which contains WinCrt. }
TYPE
comparisonType = ( less, greater, equal);
ListElementType = integer;
NodePtrType = ^NodePtr;
NodePtr = RECORD
info : ListElementType;
next : NodePtrType;
END;
list_type = RECORD
length : integer;
data : NodePtrType;
currentItem : NodePtrType;
END;
VAR
list : list_type;
ElementPtrType : NodePtrType;
newElement : ListElementType;
ans : char; { loop control }
PROCEDURE create_list(var L:list_type);
BEGIN
L.data := NIL;
L.length := 0;
writeln;
writeln('List created');
writeln;
writeln(logfile); { LOGFILE }
writeln(logfile, 'List created'); { LOGFILE }
writeln(logfile);
END;
PROCEDURE destroy_list(var L:list_type);
VAR
temp : list_Type;
BEGIN
L.length:=0;
while L.data <> NIL do
begin
temp.data := L.data;
L.data := L.data^.next;
dispose(temp.data);
end;
writeln;
writeln('List Destroyed');
writeln;
writeln(logfile); { LOGFILE }
writeln(logfile, 'List Destroyed'); { LOGFILE }
writeln(logfile);
END;
FUNCTION length (L:list_type) : integer;
BEGIN
length := L.length
END;
FUNCTION empty(L:list_type) : boolean;
BEGIN
if L.data = NIL then
empty := true
else
empty := false
END;
FUNCTION full(L:list_type) : boolean;
BEGIN
full := false
END;
FUNCTION compare(num1, num2 : ListElementType): ComparisonType;
BEGIN
if num1 < num2 then
compare := less
else if num1 > num2 then
compare := greater
else
compare := equal;
END;
PROCEDURE insert(var L:list_type; newElem:ListElementType);
VAR
NewNode : NodePtrType;
PredLoc : NodePtrType;
location: NodePtrType;
MoreToSearch : boolean;
BEGIN
location := L.data;
PredLoc := NIL;
MoreToSearch := location <> NIL;
L.length := L.length + 1;
{* Find insertion point *}
while MoreToSearch do
case compare (newElem, location^.info) of
greater :
begin
PredLoc := location;
location := location^.next;
MoreToSearch := location <> NIL;
end;
less : MoreToSearch := false;
end;{ case compare }
New(NewNode);
NewNode^.Info := newElem;
{* insert new node into the list *}
if PredLoc = NIL then
begin
NewNode^.Next := L.data;
L.data := NewNode
end{if then}
else {* inserting at the middle or at the end *}
begin
NewNode^.Next := PredLoc^.Next;
PredLoc^.Next := NewNode
end{else}
END;
PROCEDURE print (L: list_type);
VAR temp: list_type;
BEGIN
write('Printed List: ');
write(logfile, 'Printed List: '); { LOGFILE }
while L.data <> NIL do
begin
temp.data := L.data;
write(Temp.data^.info, ' ');
write(logfile, Temp.data^.info, ' ');
L.data := L.data^.next;
end;
writeln;
writeln(logfile);
END;
PROCEDURE rev_print(L:list_type);
VAR
temp : list_type;
BEGIN
if L.data <> NIL then
begin
temp.data := L.data;
L.data := L.data^.next;
rev_print(L);
write(Temp.data^.info, ' ');
write(logfile, Temp.data^.info, ' ');
end;
writeln;
writeln(logfile);
END;
BEGIN
{***} setup_logfile; { initialize the logfile }
writeln('Initializing program...');
create_list(List);
repeat
write('Please enter the new element as an integer: ');
readln(NewElement);
write(logfile, 'Please enter the new element as an integer: ');
writeln(logfile, NewElement); { LOGFILE }
insert(List, NewElement);
writeln;
writeln(logfile); { LOGFILE }
print(list);
writeln;
write('Would you like to enter another element? (Y/N)');
readln(ans);
writeln;
writeln(logfile); { LOGFILE }
write(logfile, 'Would you like to enter another element? (Y/N)');
writeln(logfile, ans); { LOGFILE }
writeln(logfile); { LOGFILE }
writeln;
writeln(logfile); { LOGFILE }
until (ans = 'N') or (ans = 'n');
write('Reverse List: ');
write(logfile, 'Reverse List: '); { LOGFILE }
rev_print(List);
writeln;
writeln(logfile); { LOGFILE }
destroy_list(List);
{***} display_logfile;
{***} holdscreen;
{***} close_logfile { closes logfile }
END.