Start Page: Start a new Project

Transcription

1 Introduction to Visual Basic & visual basic controls Learning outcome: Develop a Visual Basic Application start a new project know the toolbox control How to change the properties of control using properties windows Determine which events the controls on the window should recognize. Start Page: Start a new Project

2 VB Screen and its details: Menu Bar Tool bar Form Window Push Pin Main Area Tool Box Sizing Handle Properties Window

3 Example: To learn the date types of VB.Net and use in program. Form Design:

4 Source Code: Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim bi As Byte = 1 Dim n As Integer = 10 Dim si As Single = Dim d As Double = Dim dt As Date = Today Dim chr As Char = "a" Dim str As String = "welcome" Dim bl As Boolean = True If RadioButton1.Checked Then TextBox1.Text = bi ElseIf RadioButton2.Checked Then TextBox1.Text = si ElseIf RadioButton3.Checked Then TextBox1.Text = n ElseIf RadioButton4.Checked Then TextBox1.Text = d ElseIf RadioButton5.Checked Then TextBox1.Text = dt ElseIf RadioButton6.Checked Then TextBox1.Text = str ElseIf RadioButton7.Checked Then TextBox1.Text = chr ElseIf RadioButton8.Checked Then TextBox1.Text = bl End If

5 IF Block Example 1: To find the largest number from the given two numbers using IF-Block Form design Example 1: Source Code Public Class Form1 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim num1, num2 As Integer num1 = TextBox1.Text num2 = TextBox2.Text If num1 > num2 Then TextBox3.Text = num1 Else TextBox3.Text = num2 End If End Class

6 Example 2: To use radio buttons to select the choice to perform arithmetic operations like addition, subtraction, multiplication and division Form Design: Source Code: Public Class Form1 Private Sub Label2_Click(sender As System.Object, e As System.EventArgs) Handles Label2.Click Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim num1, num2 As Integer num1 = TextBox1.Text num2 = TextBox2.Text If RadioButton1.Checked Then TextBox3.Text = num1 + num2 ElseIf RadioButton2.Checked Then TextBox3.Text = num1 - num2 ElseIf RadioButton3.Checked Then TextBox3.Text = num1 * num2 ElseIf RadioButton4.Checked Then TextBox3.Text = num1 / num2 End If Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click Me.Close() End Class

7 Example: To find the given number is even or odd using if-block Form design: Source Code: Public Class Form1 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim num, res As Integer num = TextBox1.Text res = num Mod 2 If res = 0 Then MsgBox("even") Else MsgBox("odd") End If End Class

8 Example: 3 To perform the string handling function like length, concatenate, compare. Form Design Source Code: Public Class Form1 Private Sub Length(sender As System.Object, e As System.EventArgs) Handles LenButton1.Click TextBox3.Text = Len(TextBox1.Text) Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Dim a, b As String a = TextBox1.Text b = TextBox2.Text TextBox3.Text = Replace(b, "o", a, 1, 1) Private Sub Button10_Click(sender As System.Object, e As System.EventArgs) Handles Button10.Click Me.Close() Private Sub Button9_Click(sender As System.Object, e As System.EventArgs) Handles Button9.Click TextBox3.Clear() Private Sub Button6_Click(sender As System.Object, e As System.EventArgs) Handles Button6.Click Dim a, b As String Dim n As Integer a = TextBox1.Text b = TextBox2.Text n = StrComp(a, b) If n = 1 Then TextBox3.Text = "Not Same" Else TextBox3.Text = "Same"

9 End If Private Sub Button7_Click(sender As System.Object, e As System.EventArgs) Handles Button7.Click TextBox3.Text = StrReverse(TextBox1.Text) Private Sub Button5_Click(sender As System.Object, e As System.EventArgs) Handles Button5.Click Dim a, b As String a = TextBox1.Text b = TextBox2.Text TextBox3.Text = a + b End Class Example: To highlight the text in a text box using highlighting text properties like selection length and selection start. Form Design: Source Code: Public Class Form1 Private Sub TextBox2_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBox2.TextChanged TextBox1.SelectionStart = 0 TextBox2.SelectionLength = Len(TextBox2.Text) End Class

10 Example: To use combo box and list box to select the choice from the user. Form Design: After adding the combo box from the tool box add the item list from the properties of combo box using items property as shown below. Source code: Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click TextBox1.Text = ComboBox1.SelectedItem End Class

11 Form Design: After adding the list box from the tool box add the item list from the properties of list box as shown in the below figure. Source Code: Public Class Form1 Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click TextBox1.Text = ListBox1.SelectedItem End Class

12 Example: Grade Computation If Score>=90 and Attendance=100 grade=a If Score>=80 and Attendance>90 grade=b If Score>=60 and Attendance >=60 grade=c Otherwise grade=f Form Design: Source Code: Public Class Form1 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim score, attendance As Double score = CDbl(TextBox1.Text) attendance = CDbl(TextBox2.Text) If score >= 90 And attendance = 100 Then TextBox3.Text = "A" ElseIf score >= 80 And attendance >= 90 Then TextBox3.Text = "B" ElseIf score >= 60 And attendance >= 60 Then TextBox3.Text = "c" Else TextBox3.Text = "F" End If End Class

13 Example: Select Case Form design: Source Code: Public Class Form1 Private Sub TextBox1_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBox1.TextChanged TextBox1.SelectionStart = 0 TextBox1.SelectionLength = Len(TextBox1.Text) TextBox1.Focus() Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim pos As Integer = TextBox1.Text Select Case pos Case 1 TextBox2.Text = "win" Case 2 TextBox2.Text = "Place" Case 3 TextBox2.Text = "Show" Case 4, 5 TextBox2.Text = "you almost placed money" Case Else TextBox2.Text = "out of money" End Select End Class

14 Loops or Repetitive Statements: Example: Do Loop : Program to display numbers from 1 to 10 using Do-loop. Do Loop Syntax: Do While condition Statement Loop Form design: Source Code: Public Class Form1 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim i As Integer = 0 Do End Class ListBox1.Items.Add(i) i = i + 1 Loop Until i = 10

15 Example: For...Next Loop. For Next Loop Syntax Form Design: Source Code: Public Class Form1 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click For i As Integer = 1 To 10 ListBox1.Items.Add(i) Next End Class

16 Example: While..Loop While Loop Syntax: While condition Statement Increment End While Form Design: Source Code: Public Class Form1 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim i As Integer = 1 While i <= 10 ListBox1.Items.Add(i) i = i + 1 End While End Class

17 VB Program to connect MS-Access database. Create a Student database and add a table course with the following fields as given below, and save the file on desktop. Save this file on desktop: Student.accdb Follow the steps in VB:

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