Diploma in Information Technology

Module IX: Programming with C#.NET

Rasan SamarasingheESOFT Computer Studies (pvt) Ltd.No 68/1, Main Street, Pallegama, Embilipitiya.

Contents1. Introduction to .NET Framework2. .NET Framework Platform Architecture3. Microsoft Visual Studio4. C# Language5. C#, VS and .NET Framework Versions6. Your First C# Application7. Printing Statements8. Comments in C#9. Common Type System10. Value Types and Reference Type11. Variables Declaration in C#12. Type Conversion13. Arithmetic Operators14. Assignment Operators15. Comparison Operators16. Logical Operators17. If Statement18. If… Else Statement19. If… Else if… Else Statement20. Nested If Statement21. Switch Statement22. While Loop23. Do While Loop

23. For Loop24. Arrays25. Accessing Arrays using foreach Loop26. Two Dimensional Arrays27. Classes and Objects in C#28. Inheritance in C#29. Partial Classes30. Namespaces31. Windows Forms Applications32. Using Buttons, Labels and Text Boxes33. Displaying Message Boxes34. Error Handling with Try… Catch… finally…35. Using Radio Buttons36. Using Check Boxes37. Using List Boxes38. Creating Menus39. Creating ToolStrips40. MDI Forms41. Database Application in C#42. Creating a Simple Database Application43. SQL Insert / Update / Retrieving / Delete44. SQL Command Execute Methods45. Data Sets

Introduction to .NET Framework

• The .NET Framework is a software framework developed by Microsoft that runs primarily on Microsoft Windows.

• It includes a large library and provides language interoperability across several programming languages.

• Programs written for .NET Framework execute in a software environment known as CLR.

• .NET Framework is intended to be used by most new applications created for the Windows platform.

.NET Framework Platform Architecture

Microsoft Visual Studio

• Microsoft Visual Studio is an integrated development environment (IDE) from Microsoft…

• To develop Windows Forms or WPF applications, web sites, web applications, and web services…

• For Microsoft Windows, Windows Mobile, Windows CE, .NET Framework and Microsoft Silverlight.

C# Language

C# is a general purpose, object oriented programming language developed by Microsoft within its .NET initiative led by Anders Hejlsberg.

C# Language Features

• Boolean Conditions • Automatic Garbage Collection • Standard Library • Assembly Versioning • Properties and Events • Delegates and Events Management • Easy-to-use Generics • Indexers • Conditional Compilation • Simple Multithreading • LINQ and Lambda Expressions • Integration with Windows

C#, VS and .NET Framework Versions

C# Version Visual Studio Version .NET Framework VersionC# 1.0 Visual Studio .NET 2002 .NET Framework 1.0

C# 1.2 Visual Studio .NET 2003 .NET Framework 1.1

C# 2.0 Visual Studio 2005 .NET Framework 2.0

C# 3.0 Visual Studio 2008Visual Studio 2010

.NET Framework 2.0

.NET Framework 3.0

.NET Framework 3.5

C# 4.0 Visual Studio 2010 .NET Framework 4

C# 5.0 Visual Studio 2012Visual Studio 2013 .NET Framework 4.5

Your First C# Application

using System;

namespace myspace{

class FirstApp{ static void Main() { Console.WriteLine(“Hello World!”); }}

}

Printing Statements

Console.Write(“Hello World!”); //prints a text

Console.WriteLine(“Hello World!”); //prints text and starts a new line

Console.Write(“Hello \nWorld!”); //line breaks

Console.Write(“Hello {0}”, “Esoft”); //variable displaying

Comments in C#

Single line comments

// this is a single line comment

Multiline comments

/* this is a multilinecomment*/

Common Type System

Value Types and Reference TypePredefined Value Types

sbyte -128 to 127 8 bitsbyte 0 to 255 8 bitsshort -32,768 to 32,767 16 bitsushort 0 to 65,535 16 bitsint -2,147,483,648 to 2,147,483,647 32 bitsuint 0 to 4,294,967,295 32 bitslong -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 64 bitsulong 0 to 18,446,744,073,709,551,615 64 bitschar 16 bit Unicode character 16 bitsfloat -3.4 x 1038 to + 3.4 x 1038 32 bitsdouble (+/-)5.0 x 10-324 to (+/-) 1.7 x 10308 64 bitsdecimal (-7.9 x 1028 to 7.9 x 1028) / 100 to 28 128 bitsbool Holds true or false 1 bit

Predefined Reference Typesstring Represents a string of Unicode characters 20+ bitsobject Represents a general purpose type 8+ bits

Variable Declaration in C#

Variable declarationtype variable_list;

Variable declaration and initializationtype variable_name = value;

Variable Declaration in C#

int a, b, c; // declares three ints, a, b, and c.

int d = 3, e, f = 5; // declares three more ints, initializing d and f.

bool z = 5>2; // declares and initializes z.

double pi = 3.14159; // declares an approximation of pi.

char x = 'x'; // the variable x has the value 'x'.

Type Conversion

• Implicit Conversion – No special syntax is required because the

conversion is type safe and no data will be lost.

• Explicit Conversion– Require a cast operator, and information might be

lost in the conversion.

• Conversions with helper classes– To convert between non-compatible types.

Implicit Conversion

int x = 123;double y = x;

Explicit Conversion

double y = 123.5;int x = (int)y;

Conversions with helper classes

String x = "123";int y = Int.Parse(x);int z = Convert.ToInt32(x);

Arithmetic Operators

Operator Description Example+ Addition X + Y will give 60

- Subtraction X - Y will give -20

* Multiplication X * Y will give 800

/ Division Y / X will give 2

% Modulus Y % X will give 0

++ Increment Y++ gives 41

-- Decrement Y-- gives 39

X = 20, Y = 40

Assignment Operators

Operator Example

= Z = X + Y will assign value of X + Y into Z

+= Z += X is equivalent to Z = Z + X

-= Z -= X is equivalent to Z = Z - X

*= Z *= X is equivalent to Z = Z * X

/= Z /= X is equivalent to Z = Z / X

%= Z %= X is equivalent to Z = Z % X

Comparison Operators

Operator Example

== (X == Y) is false.

!= (X != Y) is true.

> (X > Y) is false.

< (X < Y) is true.

>= (X >= Y) is false.

<= (X <= Y) is true.

X = 50, Y = 70

Logical Operators

Operator Name Example

&& AND (X && Y) is False

|| OR (X || Y) is True

! NOT !(X && Y) is True

X = True, Y = False

If Statement

if(Boolean_expression){ // Statements will execute if the Boolean

expression is true}

Boolean Expression

Statements

True

False

If… Else Statement

if(Boolean_expression){ // Executes when the Boolean expression is true}else{ // Executes when the Boolean

expression is false}

Boolean Expression

Statements

True

False

Statements

If… Else if… Else Statementif(Boolean_expression 1){ // Executes when the Boolean expression 1 is true}else if(Boolean_expression 2){ // Executes when the Boolean expression 2 is true}else if(Boolean_expression 3){ // Executes when the Boolean expression 3 is true}else { // Executes when the none of the above condition is true.}

If… Else if… Else Statement

Boolean expression 1

False

Statements

Boolean expression 2

Boolean expression 3

Statements

Statements

False

False

Statements

True

True

True

Nested If Statementif(Boolean_expression 1){ // Executes when the Boolean expression 1 is true if(Boolean_expression 2) { // Executes when the Boolean expression 2 is true }}

Boolean Expression 1

True

False

StatementsBoolean Expression 2

True

False

Switch Statement

switch (value) { case constant: // statements break; case constant: // statements break; default: // statements break; }

While Loop

while(Boolean_expression){ // Statements}

Boolean Expression

Statements

True

False

Do While Loop

do{ // Statements}while(Boolean_expression);

Boolean Expression

Statements

True

False

For Loop

for(initialization; Boolean_expression; update){ // Statements}

Boolean Expression

Statements

True

False

Update

Initialization

Arrays

10 30 20 50 15 35

0 1 2 3 4 5

Size = 6

Element Index No

An Array can hold many values in a same data type under a single name

A single dimensional array

Building a Single Dimensional Array

// creating an ArrayDataType[] ArrayName = new DataType[size];

// assigning valuesArrayName[index] = value;ArrayName[index] = value;……..

Building a Single Dimensional Array

char[] letters = new char[4];

letters[0] = ‘O’;letters[1] = ‘P’;letters[2] = ‘Q’;letters[3] = ‘R’;

0 1 2 3

O P Q R

0 1 2 3

letters

letters

Values in an Array can access by referring index number

Building a Single Dimensional Array

// creating an array using array initializerDataType[] ArrayName = {element 1, element 2,

element 3, … element n};

int[] marks = {10, 20, 30, 40, 50}; 10 20 30 40

0 1 2 3

intArr

50

4

Accessing Arrays using foreach Loop

// creating an Arrayint[] marks = {10, 29, 30, 40, 50, 70};

// accessing array elementsforeach(int n in marks){System.Console.WriteLine(n);}

Two Dimensional Arrays

5 10 15

25 50 75

0 1 2

0

1

int[,] myMatrix = new int[2,3];

myMatrix[0,0] = 5;myMatrix[0,1] = 10;myMatrix[0,2] = 15;myMatrix[1,0] = 25;myMatrix[1,1] = 50;myMatrix[1,2] = 75;

Rows Columns

Column Index

Row Index

Two Dimensional Arrays

Using array initializer…

int[,] myMatrix = new int[2,3] {{5,10,15},{25,50,75}};

int[,] myMatrix = {{5,10,15},{25,50,75}};

Or

Classes and Objects in C#

Method

Student

nameage

Register()

class Student{

public String name;public int age;

public Student(){}

public void Register(){Console.WriteLine(“Registered!”);}

}

Attributes

Constructor

C# Objects

Student st = new Student(); //creating an object //Assigning values to Attributesst.name = “Roshan”; st.age = 20;

//calling methodst.Register();

Inheritance in C#class Animal{//attributes and methods}

class Lion : Animal{//attributes and methods}

class Cat : Animal{//attributes and methods}

Animal

Lion Cat

Partial Classespartial class Student{public int age;}

partial class Student{public String name;}

partial class Student{public String address;

public void Register(){Console.Write("Student Registered");}}

Partials of the same class

Namespaces

• Namespace is an organization construct.

• It’s a group of collected types.

• It’s helping to understand how the code base is arranged.

• Namespaces are not essential for C# programs.

namespace esoft{

class ditec{

}

class dise{

}

}

Importing Namespaces

Importing Namespace by using “using” directiveusing System.Linq;

Importing Namespace with alias directiveusing ns = System.Linq;

Direct accessing NamespacesSystem.Console.WriteLine(“hello”);

Windows Forms Applications

• A Windows Forms application is an event-driven application supported by Microsoft's .NET Framework.

• This model provides object-oriented, extensible set of classes that enable you to develop rich Windows applications.

Using Button, Labels and Text Boxes

private void button1_Click(object sender, EventArgs e){ label2.Text = "Welcome " + textBox1.Text;}

Displaying Message Boxes

MessageBox.Show("Hello World","MessageBox Demo",MessageBoxButtons.YesNo,MessageBoxIcon.Information);

MessageBox.Show("Hello World“);

Error Handling with Try… Catch… finally…

try{//Protected code }catch (Exception ex){//Catch block}finally{//The finally block always executes}

Using Radio Buttons

private void button1_Click(object sender, EventArgs e){ if (radioButton1.Checked) { MessageBox.Show("You have chosen Black"); } else { MessageBox.Show("You have chosen White"); } }

Using Check Boxes

private void button1_Click(object sender, EventArgs e){ if (checkBox1.Checked) { MessageBox.Show("You have accepted Terms of Agreement"); } else { MessageBox.Show("You haven't accepted Terms of Agreement"); } }

Using List BoxesStatements for each button click events

listBox1.Items.Add(textBox1.Text);

listBox1.Items.AddRange(new String[] { “America", “Japan", “India" });

listBox1.Items.Insert(0, textBox1.Text);

listBox1.Items.Remove(listBox1.SelectedItem);

listBox1.Items.RemoveAt(int.Parse(textBox1.Text));

listBox1.Items.Clear();

listBox1.Sorted = true;

Creating Menus

private void newToolStripMenuItem_Click(object sender, EventArgs e){ MessageBox.Show("You have clicked New Menu item!");}

Creating ToolStrips

private void newToolStripButton_Click(object sender, EventArgs e){ MessageBox.Show("You have clicked newToolStripButton!");}

MDI Forms

private void document1ToolStripMenuItem_Click(object sender, EventArgs e){ Document_One form1 = new Document_One(); form1.MdiParent = this; form1.Show();}

Database Application in C#

Application DataBase

Insert, Update, Retrieving and Delete Processes

Creating a Simple Database Application

Creating a simple database application involved with following steps.

1. Import the namespaces2. Creating a SQL Connection3. Open SQL Connection4. Create a SQL Command5. Execute the SQL Command6. Extract data from SQL Data Reader7. Clean up the environment

Creating a Simple Database Applicationusing System;using System.Data.SqlClient;

class Program{static void Main(string[] args) { SqlConnection con = new SqlConnection("Data Source=.\\SQLEXPRESS; Initial Catalog=esoftdb; Integrated Security=yes"); con.Open(); SqlCommand cmd = new SqlCommand("SELECT * FROM tblStudent", con); SqlDataReader rd = cmd.ExecuteReader(); while (rd.Read()) { Console.Write(rd["id"].ToString() + " "); Console.Write(rd["name"].ToString() + " "); Console.WriteLine(rd["address"].ToString()); } rd.Close(); con.Close(); Console.ReadLine();}}

1

2

345

6

7

SQL Insert / Update / Retrieving / Delete

Inserting Data into Database

SqlCommand cmd = new SqlCommand(“INSERT tblStudent VALUES(1, ‘Roshan’, ‘Colombo’)", con);

Updating Data in Database

SqlCommand cmd = new SqlCommand(“UPDATE tblStudent SET address=‘kandy’ WHERE id=1", con);

Retrieving Data from Database

SqlCommand cmd = new SqlCommand("SELECT * FROM tblStudent", con);

Deleting Data in Database

SqlCommand cmd = new SqlCommand(“DELETE FROM tblStudent WHERE id=1", con);

SQL Command Execute Methods

• ExecuteNonQuery() : Executes a Transact-SQL statement against the connection and returns the number of rows affected.

• ExecuteReader() : Sends the CommandText to the Connection and builds a SqlDataReader.

• ExecuteScalar() : Executes the query, and returns the first column of the first row in the result set returned by the query.

int n = cmd.ExecuteNonQuery();

SqlDataReader rd = cmd.ExecuteReader();

String name= cmd.ExecuteScalar();

Data Sets

Represents an in-memory cache of data.

SqlConnection con = new SqlConnection("Data Source=.\\SQLEXPRESS; Initial Catalog=esoftdb; Integrated Security=yes");SqlCommand cmd = new SqlCommand("SELECT * FROM tblStudent", con);SqlDataAdapter da = new SqlDataAdapter(cmd);DataSet ds = new DataSet();da.Fill(ds, “tblStudent”);

The End

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