C# summer training for FCIS, 2010. Lecture 1

1. Introduction to C#
FCIS
Summer training 2010, 1st year.
Mohamed Samy

2. Aims of this course

This course is an introduction to:

The Event-driven programming model

Writing GUI applications

Object oriented programming

The C# language

While learning, these resources will help you:

The lecture

The labs

The C# reference, released in parts

...but you need to practice, or all this will be
worthless

Seriously :(

3. Tools

This course uses Visual C# Express edition
(which is a free download from Microsoft)
− http://www.microsoft.com/express/Windows/

4. New ideas about programming...

Event-driven programming

Object oriented programming

Better for modeling

Objects have state and behavior (attributes and
methods).

Classes, subclasses.

Interface vs. implementation.

5. Event-driven programming
Normal program Event-driven program
main( ) main( )
{ {
doSubtask1( ); on event1 do { … }
doSubtask2( ); on event2 do { … }
doSubtask3( ); on event 3 do { … }
waitForEvents( );
}
}

6. Event-driven programming
Examples of events:

Keyboard and mouse actions.

Typing in a text box.

Renaming a file.

Arrival of data from the network.

Adding an item to a collection.

...

7. OOP – Modeling the problem

A word processor can use objects to represent:
− Paragraphs and pages
− Toolbars and dialogs
− Graphical objects

8. OOP – Modeling the problem

A strategy game can use objects to represent:
− Units and buildings
− Teams
− Strategies and algorithms

9. OOP – Modeling the problem

A desktop operating system can use objects
to represent:
− Files and folders
− Hardware devices

10. What's an Object?

An object has state and behavior.

It represents state via attributes and behavior
via methods.

It has an interface and an internal
implementation. Separating the interface from
the implementation is encapsulation.

Multiple object types can have the same
interface, thus opening the door for
polymorphism.

11. Objects and classes

Classes describe the common attributes and
behavior of related objects.

You can do OOP without classes, but most
OOP languages have them.

A C# class has fields (data members, member
variables) and methods (member functions).

Fields and methods can be static or non-
static.
− Non-static methods are also called instance methods or
object methods. Same for fields.

Classes can be superclasses or subclasses.
Superclasses provide abstraction over types.

12. Let's do some programming

"X owns Y" program

The bouncing head program

13. What can be done with objects?

Creating new objects

Reading and writing fields

Reading and writing properties

Calling methods.

14. GUI without the designer
using System.Windows.Forms;
class Program
{
static void Main()
{
Form f;
f = new Form();
f.Text = "A simple program";
f.SetBounds(20, 20, 400, 400);
Application.Run(f); // for the main form only!!
}
}

15. Namespaces

C# (actually, .net) program elements are
organized into namespaces.

To access an element in another namesoace,
either use its full name nsName.elementName
or import all the names from the namespace
with using ...;

To define your own namespaces, you can do
this:

namespace MyNS
{
class ABC { ... }
class DEF { … }
}

16. Instantiation

The declaration
Form f;
Tells the compiler the type of ' f ', but it does not
create a new object.

The only way to create an object is with new
f = new Form( );

New does 3 things
− Allocate memory for the object
− Initialize the object
− Return a reference to the object as the value of the new
expression.

Note: A reference is a number that's used to access
an object. It's similar (but not the same) to pointers.

17. Setting properties

The statement
f.Text = "A simple program";
is the setting of a property (properties looks like
member variables, but act like functions).

You can also set member variables with the same
syntax. Member variables work mostly like C++'s
structs.

18. Setting properties / calling methods

The statement
f.SetBounds(20, 20, 400, 400);
Is a method call. In this case SetBounds is an
instance method since it needs an object reference
' f ' to be called.

The statement
Application.Run(f);
Is calling the static method Run defined in the class
Application. It is a static method since it doesn't
need an object reference; but only a class name.

19. Terminology
Related names Element
Instance Object
Data member, Member variable,
Field
attribute
Member function Method
Class method Static method
Instance method, object method. Non-static method
Note
While the names are conceptually related, they do not necessarily
have the exact same meaning.

20. Next time...

Reference types, Arrays, foreach...

Graphics

Handling KB events

Remember to download the reference!