04/09/2014

Week 01: Introduction

• Programming Paradigms
• Dot Net Framework Architecture
• C# Compilation and Execution
• Structure of a C# Program
• Console and Windows Applications

Outline

Programming Paradigms

• Structured Programming

• Object Oriented Programming

• Visual Programming

• Component Oriented programming

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Structured Programming

• Aimed on improving the clarity, quality, and

development time of a program

• Makes extensive use of subroutines, block

structures and loops

• ALGOL, Pascal, PL/I, C etc.

Structured Programming

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Structured Programming

Object-oriented Programming

• Programmers define the data type and the types

of operations (functions) that can be applied to
the data.

• An object includes both data and functions.

• Programmers can create relationships between

objects.

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Object-oriented Programming

Visual Programming

• Programming using meaningful visual

representation such as graphics,
drawings, animation or icons.

• Supports visual interaction

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Visual Computing
Visual
Programming
Computer
Graphics

Algorithm
Animation

Scientific
User Interfaces Visualization

End User Languages

Related Areas

• Graphical User Interfaces

• Computer Graphics
• Information Visualization / Scientific
Visualization
• End User Languages (Databases etc.)
• Special Purpose Languages (e.g. UML)
• Algorithm Animation

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.NET Framework

.NET Framework

Common Language Runtime (CLR)

• a runtime environment
• similar to Java Virtual Machine (JVM)

Framework Class Library (FCL)

• provide services for applications

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.NET Architecture

.NET is tiered and modular

.NET Framework

MicroSoft Intermediate Language (MSIL)

o CPU independent set of instructions

o All .NET languages compile into MSIL
o Similar to Java Byte Code
o Also abbreviated as IL

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C# Compilation & Execution

C# source
code
MSIL

C#
compiler
CLR

Machine
code

C# Compilation & Execution

• The C# compiler translates C# source code (.cs

files) into a special representation called
Microsoft Intermediate Language (MSIL)

• MSIL is not the machine language for any

traditional CPU, but a virtual machine

• The Common Language Runtime (CLR) then

translates MSIL format to machine code

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MSIL Advantages

o Portability between OS
.NET compliant languages are all compiled
into MSIL (portable between OS)

o Language Interoperability
Different languages can communicate easily
MSIL codes from different languages can be
linked together to form a program

Interoperability

Visual
C# VB .NET
J# .NET
Compile
into MSIL

Link the MSIL

MSIL MSIL MSIL codes

CLR generate
single application
(native code)
Windows
Native Code

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Framework Class Library

Similar to MFC for Windows Programming

FCL classes are grouped by namespaces and

exported by assemblies
o Namespace similar to Java package
o Assembly similar to .dll

FCL

Some Namespaces in FCL are

o System
o System.IO
o System.Windows.Forms
o System.Drawing

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C# Program Structure

• In C#, a program is made up of

– Program specifications (header comments,
optional)

– Library imports (optional)

– One or more class (and namespace) definitions

• A class contains one or more methods
• A method contains program statements

A Simple C# Program

// This program prints a string called "Hello, World!”

using System;

class HelloWorld
{
static void Main(string[] args)
{
Console.WriteLine(“Hello, World!”);
}
}

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Namespace

• All .NET library code are organized using namespaces

• To refer to code within a namespace,

– use qualified name (as in System.Console) or
– import explicitly (as in using System; )

using System;
class HelloWorld
class HelloWorld {
{ static void Main(string[] args)
static void Main(string[] args) {
{ System.Console.WriteLine(“Hello”);
Console.WriteLine(“Hello”); }
} }
}

Comments

– Comments are ignored by the compiler: used only

for human readers (i.e., inline documentation)

• Single-line comments use //…

// this comment runs to the end of the line

• Multi-lines comments use /* … */

/* this comment runs to the terminating

symbol, even across line breaks */

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Identifiers

• Identifiers are the words that a programmer uses

in a program

• An identifier can be made up of letters, digits, and

the underscore character, they cannot begin with a
digit

• C# is case sensitive, therefore args and Args are

different identifiers

Keywords

• Often we use special identifiers called keywords

that already have a predefined meaning in the
language
– Example: class

• A keyword cannot be used in any other way

• All C# keywords are lowercase

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C# Keywords
C# Keywords
abstract as base bool break
byte case catch char checked
class const continue decimal default
delegate do double else enum
event explicit extern false finally
fixed float for foreach get
goto if implicit in int
interface internal is lock long
namespace new null object operator
out override params private protected
public readonly ref return sbyte
sealed set short sizeof stackalloc
static string struct switch this
throw true try typeof uint
ulong unchecked unsafe ushort using
value virtual void volatile while

C# Class Structure

// comments about the class

class HelloWorld
{
class header

class body

Comments can be added almost anywhere

};

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C# Class Structure

 Each class name is an identifier

 Convention: Class names are capitalized, with

each additional English word capitalized as well
(e.g., MyFirstProgram )

 Class body starts with a left brace {

 Class body ends with a right brace }

C# Methods

Building blocks of a program

The Main() method

 Each application must have exactly one

All
programs start by executing the Main
method

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Console vs. Windows Applications

• Console Application
– No visual component
– Only text input and output
– Run under Command Prompt or DOS Prompt

• Window Application
– Forms with many different visual components
– Contains Graphical User Interfaces (GUI)
– GUI is more user friendly!

C# Console Application

using System;
Class Hello
{
static void Main(string[] args)
{
Console.Write(“Your Name Please: “);
string name = Console.ReadLine();
Console.WriteLine(“Hello “ + name);
}
}

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C# Windows Application

// Printing multiple lines in a dialog Box.

using System;
using System.Windows.Forms;

class Welcome
{
static void Main( string[] args )
{
MessageBox.Show("Welcome\n to\n C#\n programming!");
}
}

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