The document discusses linked lists and procedures for manipulating them. It defines linked lists as arrays with a non-constant size, where each element contains data and a reference to the next element. There are two types: single linked lists and double linked lists. Procedures are presented for inserting elements into and deleting elements from single linked lists in different positions.

1. Pascal Programming Language
Omar ElSabek & Fayez Ghazzawi
IT Engineering
3th year – UNKNOWN Department
programming II

2. Sets
Record
Files (Text & Binary)
Pointers
Linked Lists
Unit
Course Index :

4. So the Linked List is:
Juuust like an array with unlimited elements ,because all the
elements are reserved inside the memory in “RunTime”
So the Linked Lists were born so there is no constant size for
any array
We can say that the Linked List is an array with inconstant size

5. There are two forms for Linked Lists:
1. Single Linked Lists “SLL”
2. Double Linked Lists “DLL”

6. It has two elements:
1. TheVariable(s) with Data type(s) “the same with all the
Linked List elements”
2. The References which refers to the next element in the
Linked List
This Reference has the value of (nil) in the last element in
the Linked List

7. Program test1;
Type
L_P = ^L_R;
L_R = record
num : integer;
next : L_P;
end;
Now let’s meet with some procedures
which are used in SLL

8. It has three cases:
1. Insert an element in the first of SLL
2. Insert an element in the last of SLL
3. Insert an element anywhere else

9. Procedure Insert (var L_S: L_P; numb: integer)
Var
P,S,temp : L_P; located : boolean
Begin
new(temp);
temp^.num := numb;
temp^.next := nil;
if (L_S = nil) then
L_S := temp

10. else
begin
S := L_S;
located := false;
while (S <> nil) and (not located) do
begin
if (S^.num < numb) then
begin
P := S;
S := S^.next;
end
else
located := true;
end;

11. temp^.next := S;
if (L_S = S) then
L_S := temp
else
P^.next := temp;
end;
End.

12. It has two cases:
1. Delete the first element
2. Delete any other element

13. Procedure Delete(var L_S: L_P; numb: integer;
flag: char)
Var
S,temp : L_P; located : boolean
Begin
if (numb = L_S^.num) then
begin
flag := ‘1’;
temp := L_S;
L_S := L_S^.next;
dispose(temp);
end

14. else
begin
S := L_S;
located := false;
while (S^.next <> nil) and (not located) do
begin
if (S^.next^.num <> numb) then
S := S^.next
else
located := true;
end;

15. if (not located) then
flag := ‘2’
else
begin
flag := ‘1’;
temp := S^.next;
S^.next := temp^.next;
dispose(temp);
end;
end;
End.