Chapter 7: Queue data structure

DATA STRUCTURE
Chapter 7: Queue
Prepared & Presented by
Mr. Mahmoud R. Alfarra
2011-2012
College of Science & Technology
Dep. Of Computer Science & IT
BCs of Information Technology
http://mfarra.cst.ps

Out Line
 What is Queue data structure?
 EnQueue operation
 DeQueue operation
 Clear the Queue
 Print all data of Queue
 Search about data
 Queue Class
 Types of Queue
2

What is Queue data
structure?
 Queues are used to prioritize operating system
processes and to simulate events in the real
world, such as teller lines at banks and the
operation of elevators in buildings.
 A queue is a data structure where data enters at
the rear of a list and is removed from the front of
the list.
 Queues are an example of a first-in, first-out
(FIFO) data structure.
3
Mohame
d
Ghadeer
Ali
Ahmed
Hussam
Rear Front

Queue Operations
 The two primary operations involving queues
are adding a new item to the queue and
removing an item from the queue.
 The operation for adding a new item is called
Enqueue, and the operation for removing an
item from a queue is called Dequeue.
 The other primary operation (The Peek
method) to perform on a queue is viewing the
beginning
 item.
4

What is Queue data
structure?
5

Element of Queue
6
‫البيانات‬ ‫تراكيب‬ ‫مساق‬
‫إعداد‬ ‫العلمية‬ ‫المادة‬
/
‫أ‬
.
‫ا‬ َّ‫الفــر‬ ‫رفيق‬ ‫محمود‬
 Exactly as linked list and stack …

1- Element of Queue
(customer)
7
/
‫أ‬
.
1. class Customer {
2. public int parts;
3. public int amount;
4. public String name;
5. public Customer next;
6. public Customer() {
7. parts = 0;
8. amount = 0;
9. name = "no name"; }
10. public Customer(int parts, int amount, String name) {
11. this.parts = parts;
12. this.amount = amount;
13. this.name = name; } }

2- Class Queue of customer
8
/
‫أ‬
.
1. class QueueOfCustomer {
2. public Customer Front;
3. public Customer Rear;
4. public int length;
5. public QueueOfCustomer()
6. {
7. Front = null;
8. Rear = null;
9. length = 0;
10. }
11.}

EnQueue Operation
9
Mohame
d
Ghadeer
Ali
Rear Front
Ahmed
New item
1
2
X

EnQueue Operation
10
1. public void InQueue(Customer addCus)
2. {
3. Customer newc = addCus;
4. if (Front == null)
5. {
6. Front = newc;
7. Rear = newc;
8. newc.next = null;
9. }
10. else
11. {
12. newc.next = Rear;
13. Rear = newc;
14. }
15. length++;
16. Console.WriteLine("The new Object is added: "+length);
17. }

DeQueue operation
11
Mohame
d
Ghadeer
Ali
Rear Front
Ahmad
current

DeQueue operation
12
1. public void DeQueue() {
3. Console.WriteLine("The Queue is Empty!!");
4. else
5. {
6. Customer current;
7. Customer pre_current = Rear;
8. for (current = Rear; current.next != null; current =
current.next)
9. pre_current = current;
10. Front = pre_current;
11. length--;} }

Peek Operation
13
Front.name
front.salary
…
Front

Peek Operation
14
/
‫أ‬
.
1. public void Peek()
2. {
4. Console.WriteLine("The Queue is empty");
5. else
6. Console.WriteLine("The Data of the first is:n "+
7. Front.name +"n "+Front.amount+"n "+Front.parts);
8. }

Clear the Queue
15
1. public void Clear()
2. {
3. if (Rear == null)
4. Console.WriteLine("The Queue is Empty!!");
5. else
6. Rear = null;
7. Length = 0;
8. }

Print all data of Queue
16
Mohame
d
Ghadeer
Ali
Rear Front
Ahmed
current current current current

Print all data of Queue
17
/
‫أ‬
.
1. public void PrintAll()
2. {
3. Customer current;
4. for (current = Rear; current != null; current = current.next)
5. {
6. Console.WriteLine(" ========================== ");
7. Console.WriteLine("The Data of the element is:n " +
8. current.name + "n " + current.amount + "n " + current.parts);
9. Console.WriteLine(" ========================== ");
10. }
11. }

Search about data
18
Mohame
d
Ghadeer
Ali
Rear Front
Ahmed
current current current current

Search about data
19
/
‫أ‬
.
1. public void SearchByAmount(int amount)
2. {
3. Customer current = Rear;
4. bool flag = false;
5. while (current != null)
6. {
7. if (current.amount == amount)
8. {
9. flag = true;
10. break;
11. }
12. current = current.next;
13. }
14. if (flag == true)
15. Console.WriteLine("The element is exist!! ");
16. else
17. Console.WriteLine("The element does not exist!! ");
18. }

Queue Class
 Class of Queue available in collection space of
.Net.
20
Practice : develop a full
application using class of Queue

Types of Queue
 Linear queue
 Circular queue
 Double ended queue

Thank You …
22
Remember that: question is the key of knowledge

Ahl Eljanna 

َ
‫ه‬َ‫ن‬َ
‫و‬ ٍ
‫َّات‬‫ن‬َ
‫ج‬ ِ
‫ِف‬ َ
‫ني‬ِ
‫َّق‬‫ت‬ُ
‫ْم‬‫ل‬‫ا‬ َّ
‫ن‬ِ‫إ‬
ٍ
‫ر‬
)::(
ِ
‫ع‬ ٍ
‫ق‬ْ
‫د‬ِ
‫ص‬ ِ
‫د‬َ
‫ع‬ْ
‫ق‬َ
‫م‬ ِ
‫ِف‬
َ
‫د‬ْ‫ن‬
ٍ
‫ر‬ِ
‫د‬َ‫ت‬ْ
‫ق‬ُ
‫م‬ ٍ
‫يك‬ِ‫ل‬َ
‫م‬
)::(
23

Chapter 7: Queue data structure

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