Boolean function

[ajred]

This doesn't seem to be working the way that I planned. This is a simple decimal to binary and hex converter.

I am wanting the function to return a Boolean value so if the user enters text into the text box, it asks for a number to be entered and doesn't try to convert to binary or hex. It is because the function isn't returning True or False or something in the IfElse statement?
Thanks for any help.

[jmcilhinney]

Please don't post pictures of code. It makes it harder to read and it means that we can't copy and paste if we want to run it ourselves or edit it to show you how to make it better. Post the code as text, formatted as code.

[jmcilhinney]

That TypeCheckInt will work but it is bad code. You can get rid of it altogether and just call Integer.TryParse. It returns a Boolean that indicates whether the input is a valid representation of an Integer and it will also give you the Integer value if it returns True. Two birds with one stone and you don't get the poor performance of throwing an exception if the input is invalid.

If you don't need the value:

If Integer.TryParse(myString, Nothing) Then
    'Success
Else
    'Failure
End If

If you do need the value:

Dim myInteger As Integer
 
If Integer.TryParse(myString, myInteger) Then
    'Use myInteger here
Else
    'Failure. myInteger contains zero.
End If

[jmcilhinney]

OT, don't EVER use End to exit an application. If you want to exit a WinForms app then call Application.Exit.

[ajred]

Thanks I have modified the code (including Application.Exit) but text is still generating an error on DecNumber = CInt(TxtNumber.Text). I tried adding an additional IF statement. Why is the Else statement still running? Doesn't Integer.TryParse return false if text is entered?

Public Class Form1

    Private Sub BtnExit_Click(sender As Object, e As EventArgs) Handles BtnExit.Click
        Application.Exit()
    End Sub

    Private Sub BtnClear_Click(sender As Object, e As EventArgs) Handles BtnClear.Click
        LblHexNum.Text = " "
        LblBinaryNum.Text = " "
        TxtNumber.Clear()
    End Sub

    Private Sub BtnConvert_Click(sender As Object, e As EventArgs) Handles BtnConvert.Click
        Dim DecNumber As Integer

        If TxtNumber.Text = "" Then
            MessageBox.Show("You must enter a number", "Number Converter", MessageBoxButtons.OK, MessageBoxIcon.Information)
            TxtNumber.Focus()

        Else Integer.TryParse(TxtNumber.Text, DecNumber)
            If False Then
                MessageBox.Show("Please enter a number", "Number Converter", MessageBoxButtons.OK, MessageBoxIcon.Information)
                TxtNumber.Text = " "
            Else
                DecNumber = CInt(TxtNumber.Text)
                LblBinaryNum.Text = Convert.ToString(DecNumber, 2)
                LblHexNum.Text = UCase(Convert.ToString(DecNumber, 16))
            End If
        End If
    End Sub

End Class

[ajred]

Thank you. Got it working by adding False

ElseIf Integer.TryParse(TxtNumber.Text, DecNumber) = False Then

Now working perfectly

[OptionBase1]

Else Integer.TryParse(TxtNumber.Text, DecNumber)
If False Then

That's not going to work.

It should be like:

ElseIf Integer.TryParse(TxtNumber.Text, DecNumber) = False Then

And because of that faulty code, once fixed you will likely have an extra End If that needs to be removed since your above "If False" statement was creating an extra If block that is not existing with the suggested fix.

[ajred]

Yes, thanks. Works perfectly now

[techgnome]

Im sorry... but even with that fix... no... no. no no.....

First, you only need one if statement, with the TryPArse.... if that succeeds, then you have your number. If it doesn't then you show the error message...
And since I dislike negatives...

Private Sub BtnConvert_Click(sender As Object, e As EventArgs) Handles BtnConvert.Click
Dim DecNumber As Integer

If TxtNumber.Text = "" Then
MessageBox.Show("You must enter a number", "Number Converter", MessageBoxButtons.OK, MessageBoxIcon.Information)
TxtNumber.Focus()

Else Integer.TryParse(TxtNumber.Text, DecNumber)
If False Then
MessageBox.Show("Please enter a number", "Number Converter", MessageBoxButtons.OK, MessageBoxIcon.Information)
TxtNumber.Text = " "
Else
DecNumber = CInt(TxtNumber.Text)
LblBinaryNum.Text = Convert.ToString(DecNumber, 2)
LblHexNum.Text = UCase(Convert.ToString(DecNumber, 16))
End If
End If
End Sub

All thqt could be simplified down to this:

Private Sub BtnConvert_Click(sender As Object, e As EventArgs) Handles BtnConvert.Click
Dim DecNumber As Integer

If Integer.TryParse(TxtNumber.Text, DecNumber) Then
    LblBinaryNum.Text = Convert.ToString(DecNumber, 2)
    LblHexNum.Text = UCase(Convert.ToString(DecNumber, 16))
Else
    MessageBox.Show("You must enter a number", "Number Converter", MessageBoxButtons.OK, MessageBoxIcon.Information)
    TxtNumber.Text = ""
    TxtNumber.Focus()
End If
End Sub

-tg

[Shaggy Hiker]

If people are confused by the sequence of these posts, it's because a post got stuck in the mod queue, so some of you were not replying to the latest post, which you didn't see.

Ultimately, the way TG wrote it is a good one. I'm not sure what code is the current code, but what TG wrote is what SHOULD be the current code.