1. C# language
Session -3

2. Objectives
1.Understanding of the language basics to facilitate
development.
2.Basic Object Oriented Programming concepts and
C# Programming Structure.
3. Language fundamentals
4.Doing our first C# Program.
5. Hands on knowledge in Visual Studio.

3. Introduction
• C# (pronounced “See Sharp”) is a simple, modern,
object-oriented programming language.
• It was made by Microsoft Corporation, more
precisely by Anders Hejlsberg.
• It was created to use all capacities of .NET
platform. The first version appeared in 2001, last
update appeared in 2010 with the C# 4.0.
• C# has its roots in the C family of languages and
will be immediately familiar to C, C++, and Java
programmers.

4. Fundamentals of Object Oriented
Programming
• OOPs design methodology is different from
traditional language like BASIC, Pascal, C etc.
Those are called the Procedural Language.
• In OOP, the emphasis is on Data and not on
procedures.
Class
• In OOP, A class describes all the attributes of
objects,as well as the methods that implement the
behavior of member object.
• A class is only a specification of a data type.
• A class is like a blue print of the Object.

5. Fundamentals of Object Oriented
Programming(Contd..)
Objects
• They are instance of classes.
• Objects are the central idea behind OOP
technology.
• An object is a bundle of variables and related
methods.
• When an object is created memory allocation
takes place.

6. Fundamentals of Object Oriented
Programming(Contd..)
Three principles of object oriented programming
1.Encapsulation
• The ability to hide the internals details of an object
from the outside world.
2.Inheritance
• Hierarchy is used to define more specialized classes
based on a preexisting generalized class.
3.Polymorphism
• The ability to extend functionality.

7. Abstract Class:
 We can not create a object of abstract class.
 It only allows other classes to inherit from it but can't
be instantiated.
 In C# we use Abstract Keyword.
Interface
 An interface is not a class, is entity.
 An interface has no implementation; it only has the
signature.
 Just the definition of the methods without the body.

8. Partial Class Example
• public partial class MyClass
• {
• partial void DoSomethingElse();
• public void DoSomething()
• {
Console.WriteLine("DoSomething() execution
started.");
• DoSomethingElse();
• Console.WriteLine("DoSomething() execution
finished.");

9. • Console.ReadKey();
• }
• }
• public partial class MyClass
• {
• partial void DoSomethingElse()
• {
• Console.WriteLine("DoSomethingElse()
called.");
• }
• }

10. • class Program
• {
•
• static void Main(string[] args)
• {
• MyClass mm = new MyClass();
• mm.DoSomething();
• }
• }
• }

11. OutPut
• DoSomething() execution started.
• DoSomethingElse() called.
• DoSomething() execution finished.

12. C# Language Fundamentals
• Garbage collection automatically reclaims
memory occupied by unused objects.
• Exception handling provides a structured and
extensible approach to error detection and
recovery.
• Ex: try, catch & finally
• C# is case-sensitive.

13. C# Console Application
• Console applications in C# have exactly the same purpose
as regular console applications: to provide a command line
interface with the user.
• Console applications have three main input streams:
standard in, standard out and standard error.
• “Hello World” Program using C#:
using System;
class Hello
{
static void Main(String[] args)
{
Console.WriteLine("Hello, World");
}
}

14. C# Console Application in Visual
Studio

15. C# Console Application(Contd..)
• The "System.Console" class:- The main element
in a console application is the "System.Console"
class. It contains all methods needed to control the
three streams of data.
• "ReadLine" method:- The main ways of
acquiring data from the standard input stream.
"ReadLine" reads a whole line of characters from
the buffer up to the point where the first end line
character ("n") is found. It outputs its data as
"string“.

16. Working with Visual Studio
• Microsoft Visual Studio is an Integrated Development
Environment (IDE) from Microsoft.
• It can be used to develop Console applications along
with Windows Forms applications, web sites, web
applications, and web services.
• Features :
1. Code editor
2. Debugger
3. Designer
4. Other Tools

17. Code editor
• Visual Studio includes a code editor that
supports syntax highlighting and code
completion using IntelliSense for not only
variables, functions and methods but also
language constructs like loops and queries.
• Autocomplete suggestions are popped up in a
modeless list box, overlaid on top of the code
editor.

19. Debugger
• Visual Studio includes a debugger that works both as a
source-level debugger and as a machine-level debugger.
• It works with both managed code as well as native code and
can be used for debugging applications written in any
language supported by Visual Studio.
• The debugger allows setting breakpoints (which allow
execution to be stopped temporarily at a certain position).
• The debugger supports Edit and Continue, i.e., it allows
code to be edited as it is being debugged (32 bit only; not
supported in 64 bit).
• When debugging, if the mouse pointer hovers over any
variable, its current value is displayed in a tooltip ("data
tooltips"), where it can also be modified if desired.

21. Designer
• Visual Studio includes a host of visual
designers to aid in the development of
applications. These tools include:
1. Windows Forms Designer
2. Web designer/development
3. Class designer
4. Data designer

22. Windows Forms Designer
• The Windows Forms designer is used to build GUI
applications using Windows Forms.
• It includes a palette of UI widgets and controls (including
buttons, progress bars, labels, layout containers and other
controls) that can be dragged and dropped on a form
surface.
• Layout can be controlled by housing the controls inside
other containers or locking them to the side of the form.
• Controls that display data (like textbox, list box, grid view,
etc.) can be data-bound to data sources like databases or
queries.
• The designer generates either C# or VB.NET code for the
application.

24. Web designer/development
• Visual Studio also includes a web-site editor
and designer that allows web pages to be
authored by dragging and dropping Web
controls.
• It is used for developing ASP.NET
applications and supports HTML, CSS and
JavaScript.
• It uses a code-behind model to link with
ASP.NET code.

26. Class designer
• The Class Designer is used to author and edit
the classes.
• The Class Designer can generate C# and
VB.NET code outlines for the classes and
methods.
• It can also generate class diagrams from hand-
written classes.

28. Data designer
• The data designer can be used to graphically
edit typed database tables, primary and foreign
keys and constraints.
• It can also be used to design queries from the
graphical view.

32. Polymorphism in .Net
• What is Polymorphism?
Polymorphism means same operation may
behave differently on different classes.
Example of Compile Time Polymorphism:
Method Overloading
Example of Run Time Polymorphism: Method
Overriding

33. Example of Compile Time
Polymorphism
Method Overloading
- Method with same name but with different arguments is
called method overloading.
- Method Overloading forms compile-time polymorphism.
- Example of Method Overloading:
class A1
{
void hello()
{ Console.WriteLine(“Hello”); }
void hello(string s)
{ Console.WriteLine(“Hello {0}”,s); }
}

34. Run Time Polymorphism
• Method Overriding
- Method overriding occurs when child class declares
a method that has the same type arguments as a
method declared by one of its superclass.
- Method overriding forms Run-time polymorphism.
- Note: By default functions are not virtual in C# and
so you need to write “virtual” explicitly. While by
default in Java each function are virtual.
- Example of Method Overriding:

35. • Class parent
{
virtual void hello()
{ Console.WriteLine(“Hello from Parent”); }
}
Class child : parent
{
override void hello()
{ Console.WriteLine(“Hello from Child”); }
}
static void main()
{
parent objParent = new child();
objParent.hello();
}
//Output
Hello from Child.
•

36. Summery
Language basics to facilitate development.
Basic Object Oriented Programming concepts
C# Programming Structure.
Language fundamentals
Doing our first C# Program.
Hands on knowledge in Visual Studio.