A general introduction to C#, the history, CIL, CLR, Managed languages and how to start.

1. C# Series, Week 0
Jamshid Hashimi, CodeWeekend

2. Agenda
• What is C#?
• Why C#?
• History of C#
• What is Object?
• Object Oriented Programming
• Managed Languages
• C# Syntax
• Installing C#
• Downloading and Installing Visual Studio

3. What is C#
• C# (pronounced "C-sharp") is an object-oriented programming
language from Microsoft that aims to combine the computing power
of C++ with the programming ease of Visual Basic. C# is based on C++
and contains features similar to those of Java.
• Designed by: Microsoft
• Developed by: Microsoft
• First Appeared at: 2000, 15 years ago
• Stable Release: 5.0
• Development Team Lead by: Anders Hejlsberg

4. Why C#?
• Modernized Language
• C# is a modernized version of C++
• It was C, then C++. Now it C#
• Type-safety
• You can not use uninitialized variables
• You can not walk past the end of an array
• Object Oriented
• C# goes to another level, even simple data types can be treated as Objects.
• Simplified Syntax
• C++ is powerful but not easy. C# is type safe, for example C# does away with Pointers. C# do not
allow direct memory manipulation, so pointers are not needed.
• Header files have also been removed from C#. The namespace and reference operators, :: and ->
respectively, have been replaced with a single operator, the period (.).
• int and bool data types are completely different now!
• C# removes memory management issues by using .NET garbage collection scheme.

5. Why C#?
• XML Comments
• Comments can be source code independent
• Not Just Microsoft
• Mono
• The power to be unsafe
• You can directly access to memory
• If you want to drive without a seatbelt, you are free to do so.
• Is a general purpose language
• Dev Productivity

6. History of C#
• January 1999: Anders Hejlsberg formed a team to build a new
language, named Cool, which stood for “C-like Object Oriented
Language”.
• July 2000, PDC: Language name changed to C#
• Anders Hejlsberg:
• C# Principle designer and lead architect
• Also designed Turbo Pascal and Delphi
• Stated: Flaws in other languages (e.g. C++, Java, Delphi, and Smalltalk) drove
the fundamentals of CLR, which, in return drove the design of C#.
• “It is not a clone of Java, it is much closer to C++ in its design”
• To many programmers, C# is Microsoft’s answer to Java.

7. History of C#
• The name
• Inspired by musical notation where a sharp indicates that the written note
should made a semitone higher in pitch.
• C++, means C incremented and C#, means C++ incremented. (# is made by
four +)

8. What is Object?
• Object is the foundational piece of object oriented programming language.
• An object typically makes a concept.
• An object is something e.g. customer
• An object has data e.g. customer’s first name
• An object performs action
• Make a customer preferred
• Color a car
• Change customer’s name
• Object is a thing
• To define a thing we need to talk about its characteristics.

9. What is Object?
• Suppose you are a Personnel Manager for a company and need to hire
someone in an important position.
• You select one resume, Jane
• You are Jack
• You call her
• Arrange an interview, she will fly to your location
• You two never met before, so started asking few questions from each other: height,
hair type, cloth color and briefcase color
• Without realizing it, you used objects in the course of your conversation
• You created a Person class. A class is a template used to describe an object.
• A class is an abstraction or simplification of some object your observe in the real
world.
• Objects has two basic components:
• Properties that describe the object
• Methods, or actions, that you want to associate with the object

10. What is Object?

11. Object Oriented Programming
• To be object oriented, a language is designed around the concept of
objects.
• Objects have certain properties as exhibits certain behaviors.
• It means language generally includes support for:
• Encapsulation
• Inheritance
• Polymorphism

12. Object Oriented Programming
• Encapsulation
• The wall around code
• I don’t want you to get confused
• I just want you get in touch with me with the Windows and Doors.
• A customer has a first name, but you don’t care how that’s stored. You just
want to get in and extract the information needed.
• We encapsulate to keep our code secure.

13. Object Oriented Programming
• Inheritance
• Fundamentally based on the idea of code reuse.
• You create behaviors, others can use it through inheritance channel.
• The quality you get from your parents 

14. Object Oriented Programming

15. Object Oriented Programming
• Polymorphism
• from Greek πολύς, polys, "many, much" and μορφή, morphē, "form, shape"
• Objects can appear in different shapes, forms.
• Instead of sticking with the concept of “many shapes”, perhaps the definition should
be amended to mean “many messages.”
• In essence Polymorphism means that you can send the same message to a group of
different classes and that each class will know how to respond correctly to that
message.
• clsBuilding – base class, RemoveSnow() - virtual
• clsApartment – RemoveSnow() - override
• clsCommercial – RemoveSnow() – override
• myApt.RemoveSnow()
• myComm.RemoveSnow()
• myHome.RemoveSnow() – We don’t have a RemoveSnow method for our clsHome object.
Still it outputs.

16. Managed Languages
• Managed language depends on services provided by a runtime
environment
• C# is one of many programming languages which it compiles into managed
code. (others are: F#, C++, VB and more..)
• Managed runtime in .NET is called Common Language Runtime (CLR)
• Common Language Runtime (CLR) provides:
• Automatic Memory Management
• Exception Handling
• Standard Types
• Security

17. Managed Languages
• Managed Code
• Managed code is a code that has its execution managed by .NET framework
Common Language Runtime (CLR)
• When you compile C# code to .exe, it is compiled to Common Intermediate
Language (CIL), bytecode.
• Whenever you run a CIL executable, it is executed on Microsoft Common
Language Runtime (CLR) virtual machine.
• You must have the .NET runtime installed on any client machines where your
program will be running.
• C# do not compiles directly to machine code. It compiles to CIL (bytecode).
CLR executes the bytecode to machine code.

18. C# Syntax
• C# syntax is based on C and C++ syntax
• Identifiers are names of classes, methods, variables and so on
• Console, Writeline, AcceptDetails(), GetArea(), length, width, Display and so
on.
• Keywords are compiler reserved words
• Public, class, string, get, set, void and so on.
• Using keyword is used to include namespaces inside our program.

19. C# Syntax

20. C# Syntax

21. C# Syntax

22. Thank You! 