VB & VB.Net Practical Questions

& Answers

2. Create a program that demonstrates the three states of a check box. Place a checkbox control to the form and set ThreeState property to True. Set Text property of the control to “Do you think India will defeat Australia ?”.Then select CheckStateChanged event for the checkbox to evaluate the corresponding state.

3. Write a program to change the background colors of controls in a form using For Each…Next statement.

4.  Program to initialize a System.Object array with item values and then add the entire collection to the CheckedListBox using Items.AddRange() within the Form Load function. When the Add Button is clicked, add the selected items from the CheckedListBox to the ComboBox. 

5. Create two context menu strips, one for Form control(Minimize, Maximize, Restore and Close) and another for textbox formatting (color and font).

6. Store and retrieve a text document using RichTextbox control

7. Create a customized (your own features) web browser.

8. Write procedure and code to Create a usercontrol for validating Email address.

10.Using the previous database add all student names into a ComboBox. The entire record of the student name selected  in the ComboBox, has to be displayed.

Answer to Question-1

Public Class SimpleCalculator

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _

     System.EventArgs) Handles Button1.Click

  txtResult.Text = Val(txtNum1.Text) + Val(txtNum2.Text)

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, _

    ByVal e As System.EventArgs) Handles Button2.Click

 txtResult.Text = Val(txtNum1.Text) - Val(txtNum2.Text)

    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, _

    ByVal e As System.EventArgs) Handles Button3.Click

  txtResult.Text = Val(txtNum1.Text) * Val(txtNum2.Text)

    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, _

    ByVal e As System.EventArgs) Handles Button4.Click

        txtResult.Text = Val(txtNum1.Text) / Val(txtNum2.Text)

    End Sub

End Class

Answer to Question-2

Public Class CheckBoxThreeState

    Private Sub CheckBox1_CheckStateChanged(ByVal sender As Object, _

    ByVal e As System.EventArgs) Handles CheckBox1.CheckStateChanged

        Select Case (CheckBox1.CheckState)

            Case CheckState.Unchecked

                MsgBox("No, India will not defeat Austraila ")

            Case CheckState.Checked

                MsgBox("Yes, India will defeat Austraila ")

            Case CheckState.Indeterminate

                MsgBox("Cannot Say ")

        End Select

    End Sub

End Class

Answer to Question-3

Public Class Form1

Private Sub Form1_Load(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles MyBase.Load

             For Each thisControl As System.Windows.Forms.Control _

             In Me.Controls

                thisControl.BackColor = System.Drawing.Color.LightBlue

             Next thisControl

       End Sub

End Class

Answer to Question-4

Public Class CheckedlistandCombo

  Private Sub CheckedlistandCombo_Load(ByVal sender As System.Object, _

  ByVal e As System.EventArgs) Handles MyBase.Load

        Dim ItemObject(9) As System.Object

        ItemObject(0) = "C++"

        ItemObject(1) = "Java"

        ItemObject(2) = "VisualBasic"

        ItemObject(3) = "C# Dot et"

        ItemObject(4) = "ASP.Net"

        ItemObject(5) = "PHP"

        ItemObject(6) = "XML"

        ItemObject(7) = "Flash"

        ItemObject(8) = "Photoshop"

        ItemObject(9) = "HTML"

        CheckedListBox1.Items.AddRange(ItemObject)

    End Sub

    Private Sub add()

        Dim i As Integer

        For i = 0 To (CheckedListBox1.Items.Count - 1)

            If CheckedListBox1.GetItemChecked(i) = True Then

                ComboBox1.Items.Add(CheckedListBox1.Items.Item(i))

            End If

        Next

    End Sub

    Private Sub Butto1_Click(ByVal sender As System.Object, _

    ByVal e As System.EventArgs) Handles Button2.Click

  add()

    End Sub

End Class

Answer to Question-5

Public Class Contextmenu

  Private Sub MinimizeToolStripMenuItem_Click(ByVal sender As _

  System.Object, ByVal e As System.EventArgs) Handles   

  MinimizeToolStripMenuItem.Click

        Me.WindowState = FormWindowState.Minimized

    End Sub

 Private Sub MaximizeToolStripMenuItem_Click(ByVal sender As _

 System.Object, ByVal e As System.EventArgs) Handles 

 MaximizeToolStripMenuItem.Click

        Me.WindowState = FormWindowState.Maximized

 End Sub

 Private Sub RestoreToolStripMenuItem_Click(ByVal sender As _

 System.Object, ByVal e As System.EventArgs) Handles

 RestoreToolStripMenuItem.Click

        Me.WindowState = FormWindowState.Normal

 End Sub

 Private Sub BackColorToolStripMenuItem1_Click(ByVal sender As _

 System.Object, ByVal e As System.EventArgs) Handles

 BackColorToolStripMenuItem1.Click

        ColorDialog1.ShowDialog()

        Me.BackColor = ColorDialog1.Color

 End Sub

Private Sub ForeColorToolStripMenuItem_Click(ByVal sender As _ System.Object, ByVal e As System.EventArgs) Handles

ForeColorToolStripMenuItem.Click

        ColorDialog1.ShowDialog()

        Me.ForeColor = ColorDialog1.Color

End Sub

Private Sub ExitToolStripMenuItem_Click(ByVal sender As System.Object,_

ByVal e As System.EventArgs) Handles ExitToolStripMenuItem.Click

        Application.Exit()

End Sub

Private Sub FontToolStripMenuItem_Click_1(ByVal sender As _

System.Object, ByVal e As System.EventArgs) Handles

FontToolStripMenuItem.Click

        FontDialog1.ShowDialog()

        TextBox1.Font = FontDialog1.Font

End Sub

Private Sub ColorToolStripMenuItem_Click(ByVal sender As _ System.Object, ByVal e As System.EventArgs) Handles ColorToolStripMenuItem.Click

        ColorDialog1.ShowDialog()

        TextBox1.ForeColor = ColorDialog1.Color

End Sub

End Class

Answer to Question-6

Public Class Ritchtextbox

 Private Sub Ritchtextbox_Load(ByVal sender As System.Object, ByVal e _

 As System.EventArgs) Handles MyBase.Load

        RichTextBox1.SelectionBullet = True

        RichTextBox1.SelectionIndent = 8

        RichTextBox1.SelectionHangingIndent = 15

        RichTextBox1.SelectionRightIndent = 5

  End Sub

  Public Sub SaveMyFile()

        Dim saveFile1 As New SaveFileDialog()

        saveFile1.DefaultExt = "*.rtf"

        saveFile1.Filter = "RTF Files|*.rtf"

        If (saveFile1.ShowDialog() =  _

        System.Windows.Forms.DialogResult.OK) _

        And (saveFile1.FileName.Length > 0) Then

            RichTextBox1.SaveFile(saveFile1.FileName)

        End If

    End Sub

Public Sub LoadMyFile()

  Dim openFile1 As New OpenFileDialog()

  openFile1.DefaultExt = "*.rtf"

  openFile1.Filter = "RTF Files|*.rtf"

        If (openFile1.ShowDialog() = _

        System.Windows.Forms.DialogResult.OK) _

        And (openFile1.FileName.Length > 0) Then

            RichTextBox1.LoadFile(openFile1.FileName)

        End If

    End Sub

Private Sub cmdopen_Click(ByVal sender As System.Object, ByVal e As _ System.EventArgs) Handles cmdopen.Click

        LoadMyFile()

End Sub

Private Sub cmdsave_Click(ByVal sender As System.Object, ByVal e As _ System.EventArgs) Handles cmdsave.Click

        SaveMyFile()

End Sub

End Class

Answer to Question-7

Public Class WebBrowser

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _

  System.EventArgs) Handles Button1.Click

        WebBrowser1.Navigate(cmburl.Text)

  End Sub

  Private Sub WebBrowser1_DocumentCompleted(ByVal sender As _

  System.Object, ByVal e As       System.Windows.Forms.WebBrowserDocumentCompletedEventArgs) Handles WebBrowser1.DocumentCompleted

        cmburl.Text = WebBrowser1.Url.ToString

        cmburl.Items.Add(cmburl.Text)

    End Sub

End Class

Answer to Question-8

Create a WindowsControl application named EmailValidator which contains a textbox named txtEmail and create a public function named IsValid() with return type Boolean, as shown below.

Public Class EmailValidator

    Public Function IsValid() As Boolean

        If (txtEmail.Text <> "") Then

            If txtEmail.Text.IndexOf("@") < 0 Or _
               (txtEmail.Text.Length - 4 <> txtEmail.Text.IndexOf(".") _

               And txtEmail.Text.Length - 6 <> txtEmail.Text.IndexOf(".") _

               And txtEmail.Text.Length - 3 <> txtEmail.Text.IndexOf(".")) _   

               Then

                If txtEmail.Text.IndexOf(".") > 0 And _

                   txtEmail.Text.IndexOf(".") < _

                   txtEmail.Text.IndexOf("@") Then

                       Return True

                End If

                Return False

            End If

        End If

        Return True

    End Function

End Class

Then compile the code and test it. After that create another windows application and add the EmailValidator control on it. Then add a button control on your form and the codes in click events are shown below.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _ System.EventArgs) Handles Button1.Click

        If EmailValidator1.IsValid() = False Then

            MsgBox("INvalid EmailId")

        End If

    End Sub

Answer to Question-9

Create a SQLServer Data Base named School and having a table named Student which contains the fields Rollnumber(varchar(12)),Name(varchar(20)) and Mark(Float).

The following are the VB.NET Procedure to insert records to the table Student.

Imports System.Data

Imports System.Data.SqlClient

Public Class Form1

Dim cnn as New SqlConnection

  Private Sub Form1_Load(ByVal sender As System.Object, _

  ByVal e As System.EventArgs) Handles MyBase.Load

    connstr As String = "Data Source=SYSTEM-9B98B862\SQLEXPRESS; _

    Initial Catalog=School;Integrated Security=True"

    'Initialize the connection

    cnn = New SqlConnection(connstr)   

     'Oppen connection

    cnn.Open()

   End Sub

Private Sub clear()

        txtname.Text = ""

        txtmark.Text = ""

        txtroll.Text = ""

        txtroll.Focus()

End Sub

Private Sub cmdadd_Click_1(ByVal sender As System.Object, ByVal e As_

System.EventArgs) Handles cmdadd.Click

   Dim constr As String

   Dim cmd As SqlCommand

   If txtname.Text <> "" And txtroll.Text <> "" And _

   txtsalary.Text <> "" Then

            constr = "insert Student (Rollnumber, Name, Mark) _

            values( @roll,@name,@mark)"

            cmd = New SqlCommand(constr, cnn)

            cmd.Parameters.Add("roll", SqlDbType.NChar).Value = txtroll.Text

            cmd.Parameters.Add("name", SqlDbType.NChar).Value = txtname.Text

            cmd.Parameters.Add("mark", SqlDbType.Float).Value = txtmrk.Text

            cmd.ExecuteNonQuery()

            cmbroll.Refresh()

   End If

   clear()

 End Sub

End Class

Answer to Question-10

Imports System.Data

Imports System.Data.SqlClient

Public Class FrmStudent

Dim cnn as New SqlConnection

  Private Sub FrmStudent_Load(ByVal sender As System.Object, _

  ByVal e As System.EventArgs) Handles MyBase.Load

    connstr As String = "Data Source=SYSTEM-9B98B862\SQLEXPRESS; _

    Initial Catalog=School;Integrated Security=True"

    'Initialize the connection

    cnn = New SqlConnection(connstr)   

     'Oppen connection

    cnn.Open()

    setcmb()

   End Sub

  Private Sub setcmb()

        Dim str As String

        Dim cmd As SqlCommand

        str = "select rollnumber from Studentdata"

        cmd = New SqlCommand(str, cnn)

        Dim reader As SqlDataReader = cmd.ExecuteReader()

        If cmbroll.Items.Count > 0 Then

            cmbroll.Items.Clear()

            cmbroll.Text = ""

        End If

        While reader.Read

            cmbroll.Items.Add(reader(0))

        End While

    End Sub

Private Sub cmbroll_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmbroll.SelectedIndexChanged

        cmbroll.Refresh()

        Dim constr As String

        Dim cmdselect As SqlCommand

        cnn.Close()

        cnn.Open()

        constr = "select * from Studentdata where Rollnumber=@roll"

        cmdselect = New SqlCommand(constr, cnn)

        cmdselect.Parameters.Add("roll", SqlDbType.NChar).Value = _

        cmbroll.Text

        Dim readercmb As SqlDataReader = cmdselect.ExecuteReader()

        readercmb.Read()

        While readercmb.Read()

            txtname.Text = readercmb(1)

            txtmark.Text = readercmb(2)

        End While

        readercmb.Close()

    End Sub

End Class