Answer to Question #270009 in Visual Basic for xxx

Question

Write a VB program to find out the highest and lowest mark and displayed every time the user add a mark into the list box.

The program should allow user to key in the mark on the text box and insert the mark into the list box suing the Insert button. After the mark is inserted, the highest mark and lowest mark within the list box will be displayed on the corresponding text box.

The interface should be as followed:

Example

Mark: 57(TextBox) ListBox

29

Insert(Button) 74

45

Highest:87(TextBox) 87

Lowest: 26(TextBox) 26

66

35

77

73

57

Answer 1

Public Class frmMain
    
    Private Sub btnInsert_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnInsert.Click
        
        Dim mark As Integer
        Integer.TryParse(txtMark.Text, mark)
        lstMarks.Items.Add(mark.ToString())


        Dim highestMark As Integer = Integer.Parse(lstMarks.Items(0))
        Dim lowestMark As Integer = Integer.Parse(lstMarks.Items(0))
        For i As Integer = 1 To lstMarks.Items.Count - 1
            If Integer.Parse(lstMarks.Items(i)) > highestMark Then
                highestMark = Integer.Parse(lstMarks.Items(i))
            End If
            If Integer.Parse(lstMarks.Items(i)) < lowestMark Then
                lowestMark = Integer.Parse(lstMarks.Items(i))
            End If
        Next


        txtHighestMark.Text = highestMark.ToString()
        txtLowestMark.Text = lowestMark.ToString()
    End Sub
End Class

<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Class frmMain
    Inherits System.Windows.Forms.Form

    'Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overrides Sub Dispose(ByVal disposing As Boolean)
        Try
            If disposing AndAlso components IsNot Nothing Then
                components.Dispose()
            End If
        Finally
            MyBase.Dispose(disposing)
        End Try
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.txtMark = New System.Windows.Forms.TextBox()
        Me.Label1 = New System.Windows.Forms.Label()
        Me.btnInsert = New System.Windows.Forms.Button()
        Me.lstMarks = New System.Windows.Forms.ListBox()
        Me.txtHighestMark = New System.Windows.Forms.TextBox()
        Me.Label2 = New System.Windows.Forms.Label()
        Me.txtLowestMark = New System.Windows.Forms.TextBox()
        Me.Label3 = New System.Windows.Forms.Label()
        Me.Label4 = New System.Windows.Forms.Label()
        Me.SuspendLayout()
        '
        'txtMark
        '
        Me.txtMark.Location = New System.Drawing.Point(113, 18)
        Me.txtMark.Name = "txtMark"
        Me.txtMark.Size = New System.Drawing.Size(100, 20)
        Me.txtMark.TabIndex = 0
        '
        'Label1
        '
        Me.Label1.AutoSize = True
        Me.Label1.Location = New System.Drawing.Point(45, 21)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(62, 13)
        Me.Label1.TabIndex = 1
        Me.Label1.Text = "Enter Mark:"
        '
        'btnInsert
        '
        Me.btnInsert.Location = New System.Drawing.Point(113, 44)
        Me.btnInsert.Name = "btnInsert"
        Me.btnInsert.Size = New System.Drawing.Size(100, 23)
        Me.btnInsert.TabIndex = 2
        Me.btnInsert.Text = "Insert"
        Me.btnInsert.UseVisualStyleBackColor = True
        '
        'lstMarks
        '
        Me.lstMarks.FormattingEnabled = True
        Me.lstMarks.Location = New System.Drawing.Point(113, 98)
        Me.lstMarks.Name = "lstMarks"
        Me.lstMarks.Size = New System.Drawing.Size(100, 121)
        Me.lstMarks.TabIndex = 3
        '
        'txtHighestMark
        '
        Me.txtHighestMark.Enabled = False
        Me.txtHighestMark.Location = New System.Drawing.Point(113, 225)
        Me.txtHighestMark.Name = "txtHighestMark"
        Me.txtHighestMark.Size = New System.Drawing.Size(100, 20)
        Me.txtHighestMark.TabIndex = 0
        '
        'Label2
        '
        Me.Label2.AutoSize = True
        Me.Label2.Location = New System.Drawing.Point(34, 228)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(73, 13)
        Me.Label2.TabIndex = 1
        Me.Label2.Text = "Highest Mark:"
        '
        'txtLowestMark
        '
        Me.txtLowestMark.Enabled = False
        Me.txtLowestMark.Location = New System.Drawing.Point(113, 251)
        Me.txtLowestMark.Name = "txtLowestMark"
        Me.txtLowestMark.Size = New System.Drawing.Size(100, 20)
        Me.txtLowestMark.TabIndex = 0
        '
        'Label3
        '
        Me.Label3.AutoSize = True
        Me.Label3.Location = New System.Drawing.Point(34, 254)
        Me.Label3.Name = "Label3"
        Me.Label3.Size = New System.Drawing.Size(71, 13)
        Me.Label3.TabIndex = 1
        Me.Label3.Text = "Lowest Mark:"
        '
        'Label4
        '
        Me.Label4.AutoSize = True
        Me.Label4.Location = New System.Drawing.Point(110, 78)
        Me.Label4.Name = "Label4"
        Me.Label4.Size = New System.Drawing.Size(50, 13)
        Me.Label4.TabIndex = 1
        Me.Label4.Text = "All Marks"
        '
        'frmMain
        '
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(240, 287)
        Me.Controls.Add(Me.lstMarks)
        Me.Controls.Add(Me.btnInsert)
        Me.Controls.Add(Me.Label3)
        Me.Controls.Add(Me.Label4)
        Me.Controls.Add(Me.Label2)
        Me.Controls.Add(Me.Label1)
        Me.Controls.Add(Me.txtLowestMark)
        Me.Controls.Add(Me.txtHighestMark)
        Me.Controls.Add(Me.txtMark)
        Me.Name = "frmMain"
        Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
        Me.Text = "Highest and lowest mark"
        Me.ResumeLayout(False)
        Me.PerformLayout()

    End Sub
    Friend WithEvents txtMark As System.Windows.Forms.TextBox
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents btnInsert As System.Windows.Forms.Button
    Friend WithEvents lstMarks As System.Windows.Forms.ListBox
    Friend WithEvents txtHighestMark As System.Windows.Forms.TextBox
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents txtLowestMark As System.Windows.Forms.TextBox
    Friend WithEvents Label3 As System.Windows.Forms.Label
    Friend WithEvents Label4 As System.Windows.Forms.Label

End Class