CS4443 - Modern Programming Language - I Lecture (1)

CS4443
MODERN PROGRAMMING LANGUAGE – I
Mr. Dilawar
Lecturer,
Computer Science Faculty,
Bakhtar University
Kabul, Afghanistan.

Course Objectives
• After successfully completing this course, you will be able to:
• Understand the solid concept of .NET technology.
• Learn, implement and use the C# programming skills.

Course Outline
• Introducing C#
• C# Language Fundamentals
• Introduction to OOP
• Classes and Objects
• Inheritance and Polymorphism
• Structures, Enumeration, Garbage Collection & Nested Classes
• Abstract Classes & Interfaces

Course Outline
• Arrays, Collections & String Manipulation
• Exception Handling
• Generics
• Working with Delegates and Events
• C# Language Enhancements

Text Books to Follow
• Beginning C# 6.0 Programming with a Visual Studio 2015,
Benjamin Perkins, Wrox Publishers.
• Professional C# 6 and .NET Core 1.0 by Christian Nagel, Wrox
Publishers.

Lecture Outline
• The C# language
• The .NET Architecture and .NET Framework
• CLR, MSIL, JITers, FCL, CLS, CTS and GC
• C# compare to C++
• Development Environment
• Console Applications and Windows Form Application
• Working with First Hello World Program in C#
• Understanding namespaces, using keyword, class keyword, main() method
and comments in C#

The C# Language
• It is an OOP language and has its core, many similarities to Java, C++
and VB.
• It combines the power and efficiency of C++, the simple and clean OO design
of Java and the language simplification of VB.
• To understand more clearly, Let’s have discussion on .NET framework
first.

The .NET Architecture and .NET Framework
• To understand clearly about the mentioned concepts let’s first have a
look on some terms.
• Common Language Runtime (CLR)
• Microsoft Intermediate Language (MSIL) code
• Just In Time Compilers (JITers)
• Framework Class Library (FCL)
• Common Language Specification (CLS)
• Common Type System (CTS)
• Garbage Collection (GC)

• Common Language Runtime (CLR)
• Also called .NET runtime in short.
• It is a framework layer that resides above
the OS and handles the execution of all the
.NET application.
• Or simply, CLR is used to run .NET programs.
• The program goes through the CLR while
executing.

• Microsoft Intermediate Language (MSIL) Code
• In .NET complaint language, the source code is not directly converted into
binary code.
• It is converted to an intermediate code known as MSIL.
• MSIL code is interpreted by CLR.
• MSIL is OS and hardware-independent code that is later converted to
executable code (native code).
• Cross language relationships are possible as MSIL code is similar for each .NET
language.

• Microsoft Intermediate Language (MSIL) Code

• Just In Time Compilers (JITers)
• When IL code needs to be executed, the CLR invokes the JIT compiler.
• The JIT generates the native code (.exe or .dll) from IL.
• Generates machine specific and OS specific code.
• The just-in-time part of the name reflects the fact that CIL code is compiled
only when it is needed.
• The CLR reuses the same copy without re-compiling.

• Framework Class Library(FCL)
• FCL is a huge framework (or Base) Class Library (FCL) for common, usual tasks.
• FCL contains thousands of classes to provide access to Windows API and
common functions like string manipulation, common data structures, IO,
streams, threads, security, network programming, windows programming,
web programming, data access etc…
• It is simply the largest standard library ever shipped with any development
environment or programming languages.
• The classes in FCL can be used in program as any other class.

• Earlier, we used the term ‘.NET Complaint Language’ and stated that all the
.NET complaint languages can make use of CLR and FCL.
What makes a language a
.NET complaint language?

• The answer is the Common Language Specification (CLS).
• Microsoft has released a small set of specifications that each language should
meet to qualify as a .NET complaint language.
• CLS basically addresses language design issues and lays down certain
standards.
• For instance, there shouldn’t be any global function declarations, no pointers, no
multiple inheritance and things like that.
• The more you keep your code inside the boundary of CLS, it is guaranteed to
be usable in any other .NET language.

• Common Type System (CTS)
• CTS defines the basic data types that IL understands.
• Each .NET complaint language should map its data types to these standard data types.
• Makes it possible for the 2 languages to communicate with each other by passing/receiving
parameter's to and from each other.
• E.g. CTS defines a type, Int32, an integral data type of 32 bits (4 bytes) which is mapped by
C# through int and VB.NET through its Integer data type.

• Garbage Collection (GC)
• CLR also contains the Garbage Collector (GC), which runs in a low-priority
thread and checks for un-referenced, dynamically allocated memory space.
• It finds some data that is no longer referenced by any variable/reference, it
re-claims it and returns it to the OS.
• The standard Garbage Collector frees the programmer from keeping track of
dangling data.

• The .NET framework is the
combination of layers of CLR, FCL,
Data and XML classes and our
Windows, Web applications, and Web
Services.
• The .NET framework consists
primarily of a huge library of code
that you use from your client
languages such as C# using OOP
techniques.

• This library is categorized into different modules.
• E.g. one module contains the building blocks for Windows applications,
another for network programming, and another for Web development.
• Part of the .NET library defines some basic types – CTS.
• A type is representation of data.
• It also includes the CLR, which is responsible for the execution of all
applications developed using the .NET library.

Applications You Can Write with C#
• Console Application
• Desktop Application
• Windows Store Application
• Using WPF.
• Cloud/Web Applications
• Web APIs
• WCF
• Distributed applications.

C# Compare to C++
Do it Yourself…..!!!

Development Environment
• You can either go with VS or VCE.

Console and Windows Forms Application
• Console applications are those that don’t make use of the
graphical Windows environment.
• You won’t have to worry about buttons, menus, interaction with the
mouse pointer and so on.
• Desktop applications are applications that have the look and feel
of standard Windows applications, including the familiar icons to
maximize, minimize, and close an application.
The lab will demonstrate the creation of applications.

Working with First Hello World Program in C#

Understanding the Hello World Program
• Namespaces in C#
• A namespace is simply a logical collection of related classes in C#.
• E.g. Bundle all related database activity classes into a single namespace.
• C# doesn’t allows two classes having the same name in the program.
• Namespaces are used.
• The namespace may contain classes, events, exceptions, delegates and even
other namespaces called internal namespaces.
• Written in the body of namespace.
• Similar to packages in Java and namespaces in standard C++.

• Namespaces in C#

• The using Keyword
• It allows us to use the classes in the namespace specified.
• In the previous example, the use keyword allows us to access the classes
available in the System namespace.
• It allows us to access the classes in the referenced namespaces, not in
internal/child namespaces.
• We use dot operator and name of child namespace to access the classes of child.
• E.g. using System.Collections;

• The class Keyword
• All our C# programs contains at least one class.
• The Main() method resides in one of these classes.
• Classes are a combination of data (fields) and functions (methods) the can be
performed on the data in order to achieve the solution to our program.
• Classes in C# are defined using the class keyword followed name of class.

• The Main() Method
• The standard signature of Main() method in C# is:
static void Main(string[] args)
• The Main() method is the entry point of our program.
• The Main() method is designated as static and it will called by CLR without
making any object of HelloWorld class.
• The method is also declared as void, which describe no value return.
• string[] args is the list of parameters that can be passed to main while
executing the program from command line.

• Printing on the Console
Console.WriteLine(“Hello World”);
• Here we called WriteLine(), a static method of the Console class
defined in the System namespace.
• This method takes a string (enclosed in double quotation marks) and its
parameters and prints it on the console window.

• Comments
• Line, Block, and Documentation comment

More Interactive HelloWorld Application

Summery
• The C# language
• The .NET Architecture and .NET Framework
• CLR, MSIL, JITers, FCL, CLS, CTS and GC
• C# compare to C++
• Development Environment
• Console Applications and Windows Form Application
• Working with First Hello World Program in C#
• Understanding namespaces, using keyword, class keyword, main() method
and comments in C#

CS4443 - Modern Programming Language - I Lecture (1)

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