1. Lecture 04 Components of Programming Languages, Part III
COS220 Concepts of PLs AUBG, COS dept
Lecture 04
Components of Programming Languages, Part III
(Selected Data Structures)
Reference: R.Sebesta, Chapters 5, 6
8/22/2018
Assoc. Prof. Stoyan Bonev

2. Assoc. Prof. Stoyan Bonev
Lecture Contents:
Structures as opposed to Arrays
Presentation in C++, VB, C#, Java
List
Abstract Data Entities
Stack
Queue
Deque
Binary Tree
8/22/2018
Assoc. Prof. Stoyan Bonev

3. Structures as opposed to Arrays
Array: a collection of data items of the same type.
Simple data type: Data type used to store a single value.
Structure: A collection of simple variables.
Arrays are data structures to store a collection of data items of the same type.
Structures as opposed to arrays, are data structures to store collections of related data items that have different types. The individual component of a structure is called a member.
8/22/2018
Assoc. Prof. Stoyan Bonev

4. Assoc. Prof. Stoyan Bonev
Structures in C++ l
8/22/2018
Assoc. Prof. Stoyan Bonev

5. Structure definition (declaration)
structure specifier – no storage occupying sample
struct Person {
char name[20];// string name;
char gender;
int age;
float grade; };
8/22/2018
Assoc. Prof. Stoyan Bonev

6. Structure definition (declaration)OR
8/22/2018
Assoc. Prof. Stoyan Bonev

7. Structure definition (declaration)
Applying typedef reserved word
typedef struct {
char name[20];// string name;
char gender;
int age;
float grade;
} Person;
8/22/2018
Assoc. Prof. Stoyan Bonev

8. Structure definition (declaration)
structure specifier – applying struct reserved word.
struct Date {
int day, month, year; };
Template only which does not occupy storage /memory cells/.
8/22/2018
Assoc. Prof. Stoyan Bonev

9. Referencing a structure type
How to define a structure as a variable to be a scalar, an array or a pointer?
Date a, b;
Date c[20];
Date *ptr1;
8/22/2018
Assoc. Prof. Stoyan Bonev

10. Referencing a structure type
How to define a structure as a variable to be a scalar, an array or a pointer?
Person John, Mary;
Person ClsCos220a[23];
Person *ptr2;
8/22/2018
Assoc. Prof. Stoyan Bonev

11. Initializing structure variables
Date today = { 25, 09, 2014 };
Person peter = {“Miller”,‘m’, 19, 3.48 };
8/22/2018
Assoc. Prof. Stoyan Bonev

12. Accessing structure members
Direct component selection operator . (period)
a.day=26;
b.month=11;
c[10].year=2014;
Indirect component selection operator ─>
ptr1 = &a; ptr1─>month = 3;
8/22/2018
Assoc. Prof. Stoyan Bonev

13. Structures within structures
struct Dimension
{ int feet; float inches; };
struct Room
{ Dimension length, width; };
Room kitchen;
kitchen.length.feet = 12;
kitchen.length.inches = 2.4;
kitchen.width.feet = 10;
kitchen.width.inches = 1.8;
8/22/2018
Assoc. Prof. Stoyan Bonev

14. Functions returning structures
struct Point { int x; int y; };
Point makepoint( int xpar, int ypar) {
Point temp;
temp.x = xpar; temp.y = ypar;
return temp; }
void main()
{ Point a, b;
a = makepoint(0,0);
b = makepoint(350, 200); …
8/22/2018
Assoc. Prof. Stoyan Bonev

15. Passing structure variables as arguments to functions
struct Point { int x; int y; };
struct Rect { Point pt1, pt2; };
bool isPtinRect( Point p, Rect r) {
return p.x>=r.pt1.x && p.x<=r.pt2.x &&
p.y>=r.pt1.y && p.y<=r.pt2.y ; }
8/22/2018
Assoc. Prof. Stoyan Bonev

16. Functions with structures as arguments returning structures
struct Point { int x; int y; };
Point addpoint( Point p1, Point p2) {
Point temp; // alternate version
temp.x = p1.x + p2.x; // p1.x = p1.x + p1.y;
temp.y = p1.y + p2.y; // p1.y += p2.y;
return temp; // return p1; }
void main() { Point a, b, c; a=makepoint(0,0);
b=makepoint(40, 20); c=addpoint(b,makepoint(20, 40)); }
8/22/2018
Assoc. Prof. Stoyan Bonev

17. Parallel arrays and arrays of structures
Problem: data base for COS220students
Solution based on parallel arrays:
Alternate solution: based on array of structures:
8/22/2018
Assoc. Prof. Stoyan Bonev

18. Parallel arrays and arrays of structures
Problem: data base for COS220 students
Solution based on parallel arrays:
char *name[23];int id[23];double gpa[23];
Three parallel arrays because data items with same subscript pertain the same student
name[I] = “Peter”;
id[I] = ;
gpa[I] = 3.68;
8/22/2018
Assoc. Prof. Stoyan Bonev

19. Parallel arrays and arrays of structures
Problem: data base for COS220 students
Alternate solution: based on array of structures:
struct Stud{char *name; int id; double gpa;};
Stud ar[23];
. . .
ar[I].name = “Peter”;
ar[I].id = ;
ar[I].gpa = 3.68;
8/22/2018
Assoc. Prof. Stoyan Bonev

20. Pointers to structures
struct Person { char *name, gender; int age;};
Person Mary, family[5], *ps;
for (ps=family; ps<family+5; ps++)
// or
for (ps=&family[0]; ps<=&family[4]; ps++) {
(*ps).name = … or ps->name = …
(*ps).gender = … or ps->gender = …
(*ps).age = … or ps->age = … }
8/22/2018
Assoc. Prof. Stoyan Bonev

21. Assoc. Prof. Stoyan Bonev
Struct Employee
// Definition of struct employee
struct employee {
int id;
string name;
char gender;
int numDepend;
money rate;
money totWages; };
8/22/2018
Assoc. Prof. Stoyan Bonev

22. Assoc. Prof. Stoyan Bonev
Employee variables
// Define two struct employee variables
employee organist, janitor;
8/22/2018
Assoc. Prof. Stoyan Bonev

23. Assoc. Prof. Stoyan Bonev
Anonymous structure
// Definition of anonymous structure
struct {
int id;
string name;
char gender;
int numDepend;
money rate;
money totWages; }
organist, janitor;
8/22/2018
Assoc. Prof. Stoyan Bonev

24. 9.8 Structs as Operands and Arguments
How to do arithmetic and other operations using structs
Process entire struct using programmer defined functions
Often better to pass an entire structure rather than individual elements
8/22/2018
Assoc. Prof. Stoyan Bonev

25. Struct Copy or Assignment
struct copies
Given employee structure
employee organist, janitor;
organist = janitor;
8/22/2018
Assoc. Prof. Stoyan Bonev

26. Assoc. Prof. Stoyan Bonev
Structures in VB l
8/22/2018
Assoc. Prof. Stoyan Bonev

27. Structure definition (declaration)
structure specifier
Structure Person
Dim name as String
Dim gender As Char
Dim age As Integer
Dim grade As Single
End Structure
8/22/2018
Assoc. Prof. Stoyan Bonev 27

28. The structure template
The structure should be globally defined.
It is recommended The structure template to be typed outside any Sub or Function body.
Globally defined structure template makes it visible in all Subs/Functions that follow the definition.
8/22/2018
Assoc. Prof. Stoyan Bonev

29. Accessing structure members
Structure Person
Dim name As String,gender As Char, _
age As Integer, grade As Single
End Structure
Direct component selection operator
. (period)
Dim John, Mary As Person
John.name=“Petersen” :Mary.name=“Brown”
John.gender=‘m’ :Mary.gender=‘f’
John.age=19 :Mary.age=21
John.grade=3.45 :Mary.grade=3.87
8/22/2018
Assoc. Prof. Stoyan Bonev

30. Accessing structure members
Structure Person
Dim name As String, gender As Char, _
age As Integer, grade As Single
End Structure
Direct component selection operator
. (period)
Dim p(10) As Person
p(5).name = "stoyan"
p(5).gender = ‘m’
p(5).age = 59
p(5).grade = 3.55
Console.WriteLine("{0} {1} {2} {3}",_ p(5).name, p(5).gender, p(5).age, p(5).grade)
8/22/2018
Assoc. Prof. Stoyan Bonev

31. Functions returning structures
Structure Point
Dim x, y As Integer
End Structure
Sub Main()
Dim a, b As Point
a = makepoint(0, 0)
b = makepoint(350, 200)
Console.WriteLine("Point a coordinates are: {0} , {1}", a.x, a.y)
Console.WriteLine("Point b coordinates are: {0} , {1}", b.x, b.y)
Console.ReadLine()
End Sub
Function makepoint(ByVal px As Integer, ByVal py As Integer) As Point
Dim temp As Point
temp.x = px
temp.y = py
Return temp
End Function
8/22/2018
Assoc. Prof. Stoyan Bonev

32. Functions with structures as arguments returning structures
Structure Point
Dim x, y As Integer
End Structure
Sub Main()
Dim a, b, c As Point
a = makepoint(20, 30) : b = makepoint(350, 200)
c = addpoints(a, b)
Console.WriteLine("Point c coordinates are: {0} , {1}", c.x, c.y)
Console.ReadLine()
End Sub
Function makepoint(ByVal px As Integer, ByVal py As Integer) As Point
Dim temp As Point
temp.x = px : temp.y = py : Return temp
End Function
Function addpoints(ByVal p1 As Point, ByVal p2 As Point) As Point
temp.x = p1.x + p2.x
temp.y = p1.y + p2.y
Return temp
8/22/2018
Assoc. Prof. Stoyan Bonev

33. Assoc. Prof. Stoyan Bonev
Structure Employee
‘ Definition of structure employee
Structure employee
Dim id As Integer
Dim name, gender As String
Dim Salary As Single
End Structure
‘ Definition of two employee variables
Dim organist, janitor As employee
8/22/2018
Assoc. Prof. Stoyan Bonev

34. Accessing Members of a structure
Members are accessed using the member access operator, a period .
For structure variable s and member variable m to access m you would use the following:
Console.Writeline(“{0}”, s.m)
8/22/2018
Assoc. Prof. Stoyan Bonev

35. Accessing Members of a structure
organist.id = 1234
organist.name = “Noel Goddard”
organist.gender = ‘F’
organist.salary = 500.6
organist.salary = organist.salary + 100
organist.salary += 50
8/22/2018
Assoc. Prof. Stoyan Bonev

36. Structures as Operands and Arguments
How to do arithmetic and other operations using structures
Process entire structure using programmer defined functions
Often better to pass an entire structure rather than individual elements
8/22/2018
Assoc. Prof. Stoyan Bonev

37. Structure Copy or Assignment
structure copies
Given employee structure
Dim organist, janitor As employee
organist = janitor
8/22/2018
Assoc. Prof. Stoyan Bonev

38. Structures within structures
Structure Dimension
Dim feet As Integer, inches As Double
End Structure
Structure Room
Dim length, width As Dimension
Dim kitchen As Room
kitchen.length.feet = 12
kitchen.length.inches = 2.4
kitchen.width.feet = 10
kitchen.width.inches = 1.8
8/22/2018
Assoc. Prof. Stoyan Bonev

39. Assoc. Prof. Stoyan Bonev
Example
Structure FullName
Dim firstName As String
Dim lastName As String
End Structure
Structure Student
Dim name As FullName
Dim credits() As Integer
Structure FullName
contained, or nested,
inside Student
8/22/2018
Assoc. Prof. Stoyan Bonev

40. Assoc. Prof. Stoyan Bonev
Private Sub btnGet_Click(...) Handles btnGet.Click
Dim numYears, i As Integer
Dim person As Student …
person.name.firstName = InputBox("First Name:")
person.name.lastName = InputBox("Second Name:")
End Sub
8/22/2018
Assoc. Prof. Stoyan Bonev

41. Passing structure variables as arguments to functions
Structure Point
Dim x, y As Integer
End Structure
Structure Rect
Dim pt1, pt2 As Point
Function isPtInRect( p As Point, r As Rect) As Boolean
Return p.x >= r.pt1.x AND p.x <= r.pt2.x AND _
p.y >= r.pt1.y AND p.y <= r.pt2.y
End Function
8/22/2018
Assoc. Prof. Stoyan Bonev

42. Parallel arrays and arrays of structures
Problem: data base for COS220 students
Solution based on simple scalar variables
Solution based on parallel arrays
Alternate solution: array of structures
8/22/2018
Assoc. Prof. Stoyan Bonev

43. Parallel arrays and arrays of structures
Problem: data base for COS220 students
Suppose that you want to evaluate the exam grades for 20 students and to display the names of the students whose scores are above average.
Using simple variables would mean declaring 20 variables for the students’ names and 20 variables for the students’ ids and 20 variables for the students’ scores. Very tedious!
Dim student1 As String, id1 As Integer, score1 As Double
Dim student2 As String, id2 As Integer, score2 As Double
. . .
Dim student20 As String, id20 As Integer, score20 As Double
8/22/2018
Assoc. Prof. Stoyan Bonev

44. Parallel arrays and arrays of structures
Problem: data base for COS220 students
Much easier with arrays – one array variable for the names, and one array variable for the ids, and one array variable for the scores.
Dim name(19) As String
Dim id(19) As Integer
Dim score(19) As Double
Much more convenient with array of structures
8/22/2018
Assoc. Prof. Stoyan Bonev

45. Parallel arrays and arrays of structures
Problem: data base for COS220 students
Solution based on parallel arrays:
Dim name(19) As String
Dim id(19) As Integer
Dim score(19) As Double
Three parallel arrays because data items with same subscript pertain the same student
name(I) = “Peter”
id(I) =
score(I) = 3.68
8/22/2018
Assoc. Prof. Stoyan Bonev

46. Parallel arrays and arrays of structures
Problem: data base for COS220 students
Alternate solution: array of structures:
Structure Student
Dim name As String, id As Integer
Dim score As Double
End Structure
Dim ar(19) As Student
. . .
ar(I).name = “Peter”
ar(I).id =
ar(I).score = 3.68
8/22/2018
Assoc. Prof. Stoyan Bonev

47. Assoc. Prof. Stoyan Bonev
Structures in C# l
8/22/2018
Assoc. Prof. Stoyan Bonev

48. how to declare and use structs
public struct DayOfYear {
public int day;
public int month;
public int year;
public DayOfYear(int a, int b, int c)
day = a; month = b; year = c; }
8/22/2018
Assoc. Prof. Stoyan Bonev

49. how to declare and use structs
DayOfYear today = new DayOfYear(24, 9, 2014);
DayOfYear day1;
DayOfYear daylast;
daylast = new DayOfYear();
Console.WriteLine();
Console.WriteLine("{0} {1} {2} {0} {1} {2}", today.day, today.month, today.year);
8/22/2018
Assoc. Prof. Stoyan Bonev

50. how to declare and use structs
Structs vs. Classes
Structs may seem similar to classes, but there are important differences that you should be aware of. First of all, classes are reference types and structs are value types. By using structs, you can create objects that behave like the built-in types and enjoy their benefits as well.
Heap or Stack?
When you call the New operator on a class, it will be allocated on the heap. However, when you instantiate a struct, it gets created on the stack.
8/22/2018
Assoc. Prof. Stoyan Bonev

51. how to declare and use structs
This example declares a struct with three members: a property, a method, and a private field. It creates an instance of the struct and puts it to use.
8/22/2018
Assoc. Prof. Stoyan Bonev

52. how to declare and use structs
using System;
struct SimpleStruct {
private int xval;
public int X
get
return xval; }
set
if (value < 100)
xval = value;
public void DisplayX()
Console.WriteLine("The stored value is: {0}", xval);
class TestClass
public static void Main()
SimpleStruct ss = new SimpleStruct();
ss.X = 5;
ss.DisplayX();
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Assoc. Prof. Stoyan Bonev

53. Assoc. Prof. Stoyan Bonev
Structures in Java
Not supported in Java!
8/22/2018
Assoc. Prof. Stoyan Bonev

54. Introduction to abstract data structures
Arrays and Lists are basic fundamental data structured entities.
Stack, Queue, Deque, Binary Tree are abstract data structured entities.
Arrays and Lists serve as building elements to create abstract data structures.
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Assoc. Prof. Stoyan Bonev

55. Assoc. Prof. Stoyan Bonev
Data Structures: List
8/22/2018
Assoc. Prof. Stoyan Bonev

56. Assoc. Prof. Stoyan Bonev
Data Structures: List
List or a linked list is a data structure that consists of a sequence of data records such that in each record or node there is a field that contains a reference (i.e., a link) to the next record in the sequence.
A linked list whose nodes contain two fields: an integer value and a link to the next node
Linked lists as well as arrays provide an easy implementation for important abstract data structures, including stacks, queues, associative arrays
8/22/2018
Assoc. Prof. Stoyan Bonev

57. Data Structures: Stack
8/22/2018
Assoc. Prof. Stoyan Bonev

58. Data Structures: Stack
stack is a last in, first out (LIFO) data structure. A stack is characterized by only two operations: push and pop. The push operation adds an item to the top of the stack,. The pop operation removes an item from the top of the stack, and returns this value to the caller.
8/22/2018
Assoc. Prof. Stoyan Bonev

59. Data Structures: Queue
8/22/2018
Assoc. Prof. Stoyan Bonev

60. Data Structures: Queue
A queue is a First-In-First-Out (FIFO) data structure. In a FIFO data structure, the first element added to the queue will be the first one to be removed.
8/22/2018
Assoc. Prof. Stoyan Bonev

61. Data Structures: Queue
A queue
A priority queue
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Assoc. Prof. Stoyan Bonev

62. Data Structures: Deque
8/22/2018
Assoc. Prof. Stoyan Bonev

63. Data Structures: Deque
double-ended queue (or shortly deque, pronounced deck) is a data structure that implements a queue for which elements can only be added to or removed from the front (head) or back (tail). It is also often called a head-tail linked list.
8/22/2018
Assoc. Prof. Stoyan Bonev

64. Data Structures: Binary Tree
8/22/2018
Assoc. Prof. Stoyan Bonev

65. Data Structures: Binary Tree
binary tree is a data structure in which each node has at most two child nodes, usually distinguished as "left" and "right". Nodes with children are parent nodes. Outside the tree, there is often a reference to the "root" node (the ancestor of all nodes)
8/22/2018
Assoc. Prof. Stoyan Bonev

66. Data Structures: Binary Tree
Traverse strategies:
Top-Down
Root
Top-Down traverse to Left sub tree
Top-Down traverse to Right sub tree
Mixed
Mixed traverse to Left sub tree
Mixed traverse to Right sub tree
Bottom-Up
Bottom-Up traverse to Left sub tree
Bottom-Up traverse to Right sub tree
8/22/2018
Assoc. Prof. Stoyan Bonev

67. Thank You for Your attention