1. Chapter 5: Programming with C#
Microsoft®
Chapter 5: Programming with C#
Visual C# 2008

2. Overview Using Arrays Using Collections Using Exception Handling
Using Interfaces (optional)
Using Delegates and Events (optional)

3. Lesson: Using Arrays What Is an Array? How to Create an Array
How to Initialize and Access Array Members
How to Iterate Through an Array Using the foreach Statement
How to Use Arrays as Method Parameters
How to Index an Object

4. What Is an Array?
A data structure that contains a number of variables called elements of
the array
All of the array elements must be of the same type
Arrays are zero indexed
Arrays are objects
Arrays can be:
Single-dimensional, an array with the rank of one
Multidimensional, an array with a rank greater than one
Jagged, an array whose elements are arrays
Array methods

5. How to Create an Array
​Declare the array by adding a set of square brackets to end of the variable type of the individual elements
Syntax
type[] array-name;
Example
Int[] MyIntegerArray;
Instantiate to create
int[ ] numbers = new int[5];
To create an array of type Object
object [ ] animals = new object [100];

6. How to Initialize and Access Array Members
Initializing an array
int[] numbers = {10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0};
numbers[4] = 5;
Accessing array members
string[] animal = {"Mouse", "Cat", "Lion"};
animal[1]= "Elephant";
string someAnimal = animal[2];

7. How to Iterate Through an Array Using the foreach Statement
Using foreach statement repeats the embedded statement(s) for each element in the array
Syntax
foreach ( type identifier in expression )
statement-block
Examples
int[] numbers = {4, 5, 6, 1, 2, 3, -2, -1, 0};
foreach (int i in numbers) {
Console.WriteLine(i); }

8. How to Use Arrays as Method Parameters
Pass an array to a method
Use the params keyword to pass a variable number of arguments to a
method
public int Sum(params int[] list) {
int total = 0;
foreach ( int i in list ) {
total += i; }
return total;
...
// pe is the object providing Sum()
int value = pe.Sum( 1, 3, 5, 7, 9, 11 );

9. How to Index an Object Use this keyword, and get and set accessors
public class Zoo {
private Animal[] theAnimals;
public Animal this[int i] {
get {
return theAnimals[i]; }
set {
theAnimals[i] = value;

10. Practice: Using a foreach Statement with an Array
Hands-on Practice
In this practice, you will create an array, populate it, and use the foreach statement to print out the values in the array

11. Practice (optional): Using an Indexer
Hands-on Practice
In this practice, you will write an indexer for the Zoo class

12. Lesson: Using Collections
What Are Lists, Queues, Stacks, and Hash Tables?
How to Use the ArrayList Class
How to Use Queues and Stacks
How to Use Hash Tables

13. What Are Lists, Queues, Stacks, and Hash Tables?
Lists, queues, stacks, and hash tables are common ways to manage data
in an application
List: A collection that allows you access by index
Example: An array is a list; an ArrayList is a list
Queue: First-in, first-out collection of objects
Example: Waiting in line at a ticket office
Stack: Last-in-first-out collection of objects
Example: A pile of plates
Hash table: Represents a collection of associated keys and values
organized around the hash code of the key
Example: A dictionary

14. How to Use the ArrayList Class
ArrayList does not have a fixed size; it grows as needed
Use Add(object) to add an object to the end of the ArrayList
Use [] to access elements in the ArrayList
Use TrimToSize() to reduce the size to fit the number of elements in
the ArrayList
Use Clear to remove all the elements
Can set the capacity explicitly

15. How to Use Queues and Stacks
Queues: first-in, first-out
Enqueue places objects in the queue
Dequeue removes objects from the queue
Stacks: last-in, first-out
Push places objects on the stack
Pop removes objects from the stack
Count gets the number of objects contained in a stack or queue

16. How to Use Hash Tables
A hash table is a data structure that associates a key with an object, for
rapid retrieval
Book techBook = new Book("Inside C#", );
// ...
public Hashtable bookList; //
bookList.Add( , techBook);
Book b = (Book) bookList[ ];
// b’s title is "Inside C#”
Key
Object

17. Practice: Creating and Using Collections
Hands-on Practice
In this practice, you will use the ArrayList class

18. Lesson: Using Exception Handling
How to Use Exception Handling
How to Throw Exceptions

19. How to Use Exception Handling
Exception handling syntax
try {
// suspect code }
catch {
// handle exceptions
finally {
// always do this

20. How to Throw Exceptions
Throw keyword
Exception handling strategies
Exception types
The predefined common language runtime exception classes
Example: ArithmeticException, FileNotFoundException
User-defined exceptions

21. Practice: Using Exception Handling
Hands-on Practice
In this practice, you will use throw and catch an exception

22. Lesson: Using Interfaces (optional)
What Is an Interface?
How to Use an Interface
How to Work with Objects That Implement Interfaces
How to Inherit Multiple Interfaces
Interfaces and the .NET Framework

23. What Is an Interface? Is a reference type that defines a contract
Specifies the members that must be supplied by classes or
interfaces that implement the interface
Can contain methods, properties, indexers, events
Does not provide implementations for the members
Can inherit from zero or more interfaces

24. How to Use an Interface
An interface defines the same functionality and behavior to unrelated
classes
Declare an interface
Implement an interface
interface ICarnivore {
bool IsHungry { get; }
Animal Hunt();
void Eat(Animal victim); }

25. How to Work with Objects That Implement Interfacesis
if ( anAnimal is ICarnivore ) {
ICarnivore meatEater = (ICarnivore) anAnimal;
Animal prey = meatEater.Hunt();
meatEater.Eat( prey ); } as
ICarnivore meatEater = anAnimal as ICarnivore;
if ( meatEater != null ) {
Animal prey = meatEater.Hunt();
meatEater.Eat( prey ); }
// is and as with an object
if ( prey is Antelope ) { ... }

26. How to Inherit Multiple Interfaces
Class Chimpanzee : Animal, ICarnivore, IHerbivore { … }
Interfaces should describe a type of behavior
Examples:
Lion is-a-kind-of Animal; Lion has Carnivore behavior
Shark is-a-kind-of Animal; has Carnivore behavior
Derive Lion and Shark from abstract class Animal
Implement Carnivore behavior in an Interface

27. Interfaces and the .NET Framework
Allows you to make your objects behave like .NET Framework objects
Example: Interfaces used by Collection classes
ICollection, IComparer, IDictionary, IDictionary Enumerator,
IEnumerable, IEnumerator, IHashCodeProvider, IList
public class Zoo : IEnumerable {
. . .
public IEnumerator GetEnumerator() {
return (IEnumerator)new ZooEnumerator(
this ); }

28. Practice: Using Interfaces
Hands-on Practice
In this practice, you will implement the ICloneable interface

29. Lesson: Using Delegates and Events
How to Create a Delegate
What Is an Event?
How to Write an Event Handler

30. How to Create a Delegate
Zoo Keeper 1
Schedule lion
CheckClaws
Zoo Keeper 1
Schedule lion
CheckClaws
Medical Center
ScheduleApointment
Calls
ProcessNextPatient
Delegate
AppointmentType
Lion
CheckClaws
Antelope
CheckHooves

31. What Is an Event? Mouse and keyboard Property MouseDown, MouseUp,
MouseMove,
MouseEnter,
MouseLeave,
MouseHover
KeyPress,
KeyDown,
KeyUp
Property
FontChanged
SizeChanged
CursorChanged

32. How to Write an Event Handler
Declare events using delegates
System.EventHandler is declared as a delegate
button1.Click += new System.EventHandler(button1_Click);
Event handler is called when the event occurs
EventArgs parameter contains the event data
private void button1_Click(object sender, System.EventArgs e) {
MessageBox.Show( e.ToString() ); }

33. Practice: Declaring and Calling a Delegate
Hands-on Practice
In this practice, you will create and use a delegate

34. Review Using Arrays Using Collections Using Exception Handling
Using Interfaces
Using Delegates and Events

35. Lab 5:1: Using Arrays
Exercise 1: Sorting Numbers in an Array

36. Lab 5.2 (optional): Using Indexers and Interfaces
Exercise 1: Writing the Check Pick-up Application
Exercise 2: Using Interfaces

37. Lab 5.3 (optional): Using Delegates and Events
Exercise 1: Working with Events and Delegates