Question

In this exercise, you’ll add code to a form that converts the value the user enters based on the selected conversion type.

Conversions Conversion: Meters to feet Meters 500 Feet 1,640.40 Calculate Exit

The application should handle the following conversions:

1. Open the Conversions project. Display the code for the form, and notice the rectangular array whose rows contain the value to be displayed in the combo box, the text for the labels that identify the two text boxes, and the multiplier for the conversion as shown above. Note: An array is similar to a string with an index beginning with 0 (zero).

2. Set the DropDownStyle property of the combo box so the user must select an item from the list.

3. Add code to load the combo box with the first element in each row of the rectangular array, and display the first item in the combo box when the form is loaded.

4. Add code to change the labels for the text boxes, clear the calculated length, and move the focus to the entry text box when the user selects a different item from the combo box.

5. Test the application to be sure the conversions are displayed in the combo box, the first conversion is selected by default, and the labels change appropriately when a different conversion is selected.

6. Add code to calculate and display the converted length when the user clicks the Calculate button. To calculate the length, you can get the index for the selected conversion and then use that index to get the multiplier from the array. Test the application to be sure this works correctly.

7. Add code to check that the user enters a valid decimal value for the length. Then, test the application one more time to be sure the validation works correctly.

Here is the starting code:

Public Class Form1

Dim conversionTable(,) As String = {
{"Miles to kilometers", "Miles", "Kilometers", "1.6093"},
{"Kilometers to miles", "Kilometers", "Miles", "0.6214"},
{"Feet to meters", "Feet", "Meters", "0.3048"},
{"Meters to feet", "Meters", "Feet", "3.2808"},
{"Inches to centimeters", "Inches", "Centimeters", "2.54"},
{"Centimeters to inches", "Centimeters", "Inches", "0.3937"}}

Public Function IsPresent(ByVal textbox As TextBox, ByVal name As String) _
As Boolean
If textbox.Text = "" Then
MessageBox.Show(name & " is a required field.", "Entry Error")
textbox.Select()
Return False
Else
Return True
End If
End Function

Public Function IsDecimal(ByVal textbox As TextBox, ByVal name As String) _
As Boolean
Dim number As Decimal = 0
If Decimal.TryParse(textbox.Text, number) Then
Return True
Else
MessageBox.Show(name & " must be a decimal value.", "Entry Error")
textbox.Select()
textbox.SelectAll()
Return False
End If
End Function

Private Sub btnExit_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnExit.Click
Me.Close()
End Sub

End Class

Answer 1

Answer:

Design coading:

Coding:

Public Class txtfirst
    Dim conversionTable(,) As String = {
    {"Miles to kilometers", "Miles", "Kilometers", "1.6093"},
    {"Kilometers to miles", "Kilometers", "Miles", "0.6214"},
    {"Feet to meters", "Feet", "Meters", "0.3048"},
    {"Meters to feet", "Meters", "Feet", "3.2808"},
    {"Inches to centimeters", "Inches", "Centimeters", "2.54"},
    {"Centimeters to inches", "Centimeters", "Inches", "0.3937"}}
    Dim i As Integer = 0

    Private Sub btnexit_Click(sender As Object, e As EventArgs) Handles btnexit.Click
        Me.Close()
    End Sub

    Private Sub txtfirst_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Fill_combo()
    End Sub
    Public Function Fill_combo()
        For i As Integer = 0 To (conversionTable.GetUpperBound(0)) - 1
            cmbconversion.Items.Add(conversionTable.GetValue(i, 0))
        Next
    End Function

    Public Function IsPresent(ByVal textbox As TextBox, ByVal name As String) _
          As Boolean
        If textbox.Text = "" Then
            MessageBox.Show(name & " is a required field.", "Entry Error")
            textbox.Select()
            Return False
        Else
            Return True
        End If
    End Function
    Public Function IsDecimal(ByVal textbox As TextBox, ByVal name As String) _
           As Boolean
        Dim number As Decimal = 0
        If Decimal.TryParse(textbox.Text, number) Then
            Return True
        Else
            MessageBox.Show(name & " must be a decimal value.", "Entry Error")
            textbox.Select()
            textbox.SelectAll()
            Return False
        End If
    End Function

    Private Sub btncalculate_Click(sender As Object, e As EventArgs) Handles btncalculate.Click
        If (IsPresent(txtfirstt, txtfirstt.Text) = False) Then
        ElseIf (IsDecimal(txtfirstt, txtsecond.Text) = False) Then

        Else
            calculate(lbllfirst.Text, lblsecond.Text)
        End If

    End Sub

    Private Sub cmbconversion_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbconversion.SelectedIndexChanged
        For i As Integer = 0 To (conversionTable.GetUpperBound(0)) - 1
            If (cmbconversion.Text = conversionTable.GetValue(i, 0)) Then
                lbllfirst.Text = conversionTable.GetValue(i, 1)
                lblsecond.Text = conversionTable.GetValue(i, 2)
            End If
        Next
    End Sub

    Private Sub calculate(first As String, second As String)
        For i As Integer = 0 To (conversionTable.GetUpperBound(0)) - 1
            If (first = conversionTable.GetValue(i, 1) And second = conversionTable.GetValue(i, 2)) Then
                txtsecond.Text = Val(txtfirstt.Text) * conversionTable.GetValue(i, 3)
            End If
        Next

    End Sub

End Class

output:

if you still have any dout regarding this question please comment and if you like my code please appreciate me by thumbs up thank you.........