Chapter 6: stack data structure

1. DATA STRUCTURE
Chapter 6: Stack
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

2. Out Line
 What is Stack data structure?
 Push operation
 Pop operation
 Retrieve the data of an element
 Clear the Stack
 Print all data of stack
 Search about data
 Stack Collection
2

3. What is the Stack?
 Stack is a dynamic linear data structure.
 Data in a stack are added and removed from
only one end of the list.
3

4. What is the Stack?
4
‫البيانات‬ ‫تراكيب‬ ‫مساق‬
‫إعداد‬ ‫العلمية‬ ‫المادة‬
/
‫أ‬
.
‫ا‬ َّ‫الفــر‬ ‫رفيق‬ ‫محمود‬
 We define a stack as a list of items that are
accessible only from the end of the list, which
is called the top of the stack.
 Elements are always removed from the top,
and inserted on the top also.
 A stack is known as a Last-in, First-out (LIFO)
data structure

5. Elements of stack
5
Top
6
1
7

6. Employee’s element for stack
6
‫البيانات‬ ‫تراكيب‬ ‫مساق‬
‫إعداد‬ ‫العلمية‬ ‫المادة‬
/
‫أ‬
.
‫ا‬ َّ‫الفــر‬ ‫رفيق‬ ‫محمود‬
1. class Employee {
2. public int salary;
3. public String name;
4. Employee next;
5. public Employee()
6. {
7. salary = 300;
8. name = "no name";
9. next = null;
10. }
11. public Employee(int salary, String name)
12. {
13. this.salary = salary;
14. this.name = name; } }

7. Stack of employees
7
1. class EmployeeStack
2. {
3. Employee Top = null;
4. int length =0;
5. //the operation of stack will be inserted here
6. }

8. Push operation
8
Top
6
Top
6
1
Top
6
1
7

9. Push operation
9
‫البيانات‬ ‫تراكيب‬ ‫مساق‬
‫إعداد‬ ‫العلمية‬ ‫المادة‬
/
‫أ‬
.
‫ا‬ َّ‫الفــر‬ ‫رفيق‬ ‫محمود‬
1. public void Push(Employee NewEmp) {
2. Employee newe = NewEmp;
3. if (Top == null) {
4. Top = newe;
5. newe.next = null; }
6. else {
7. newe.next = Top;
8. Top = newe; }
9. length++;
10. Console.WriteLine("A new Employee has been added to Stack:
"+length);
11. }

10. Pop operation
10
Top
6
1
7 Top
6
1
7

11. Pop operation
11
1. public void Pop()
2. {
3. if (Top == null)
4. Console.WriteLine("Stack is Empty!!");
5. else
6. {
7. Top = Top.next;
8. length--;
9. Console.WriteLine("Now Top Points to: " +
Top.name);
10. }
11.
12. }

12. Peek operation: to display info of top
element
12
Top
6
1
7
Top.name
Top.salary
…

13. Peek operation: to display info of top
element
13
1. public void Peek()
2. {
3. if (Top == null)
4. Console.WriteLine("The Stack is Empty!!");
5. else
6. Console.WriteLine("The Employee Data:n"+
7. "Name: "+Top.name+"nSalary: "+Top.salary);
8. }

14. Clear the Stack
14
 Clearing the stack means that the top must
points to null.
Top
6
1
7

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

16. Print all data of stack
16
Top
6
1
7
next
next
current

17. Print all data of stack
17
1. public void PrintAll()
2. {
3. Employee current = Top;
4. int x =1;
5. while (current != null)
6. {
7. Console.WriteLine("Data Of Employee # "+x+" isn "+ "Name: “ +
current.name + "nSalary: "+current.salary);
8. Console.WriteLine("==============================");
9. x++;
10. current = current.next;
11. }
12. }

18. Search about data
18
Top
6
1
7
next
next
current

19. Search about data
19
‫البيانات‬ ‫تراكيب‬ ‫مساق‬
‫إعداد‬ ‫العلمية‬ ‫المادة‬
/
‫أ‬
.
‫ا‬ َّ‫الفــر‬ ‫رفيق‬ ‫محمود‬
1. public void SearchByName(String name )
2. {
3. Employee current = Top;
4. bool flag = false;
5. while ( current != null)
6. {
7. if (name.CompareTo(current.name) == 0)
8. {
9. flag = true;
10. break;
11. }
12. current = current.next;
13. }
14. if (flag == true)
15. Console.WriteLine("Exist!!");
16. else
17. Console.WriteLine("Does not Exist!!");
18. }

20. Stack Collection
 The Stack class is an implementation of the
ICollection interface that represents a LIFO
collection, or a stack.
 The class is implemented in the .NET
Framework as a circular buffer, which enables
space for items pushed on the stack to be
allocated dynamically.
 The default constructor is called as follows:
Stack myStack = new Stack();
Practice:
develop a full
application
using stack
class

21. Thank You …
21
Remember that: question is the key of knowledge

22. Ahl Eljanna 

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‫َّم‬‫ث‬‫ال‬
22