[RESOLVED] Need help finishing an assignment

I'm trying to finish an assignment for my Introduction to Visual Basic class.

I have to program an application that will determine if a word entered has consecutive letters in the alphabet as a substring of itself. Three examples are T"HI""RST"Y, AF"GH"ANI"ST"AN, and "STU""DE"NT.

This is what I have so far:

Code:

---

Public Class ConsecutiveLettersot

    'declare text input as class level variable
    Dim textInput As String

    'delcare substring locations as class level variables
    Dim locationOne As Integer
    Dim locationTwo As Integer

    Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click


        'clear read-only boxes
        lstConsecutiveLetters.Items.Clear()
        txtConcecutiveAmount.Text = ""

        'if the entry was numbers, display error
        If IsNumeric(txtEntry.Text) = False Then
            'entered text is not a number, delcare variable
            textInput = txtEntry.Text.ToUpper
        Else
            'entry was not letters
            MessageBox.Show("Please do not enter numbers.", "Error!")
            'return early
            Return
        End If

        'if the entry is less than 2 letters long
        If txtEntry.Text.Length < 2 Then
            MessageBox.Show("Entered text must be at least 2 letters long!", "Error!")
            'return early
            Return
        End If

        For i = 0 To ((textInput.Length) - 1)

            locationOne = Asc(textInput.Substring(i, 1))
            locationTwo = Asc(textInput.Substring(i + 1, 1))

            If locationTwo - locationOne = 1 Then
                lstConsecutiveLetters.Items.Add(textInput.Substring(i, 1))
            End If

            i += 1
        Next

    End Sub

End Class

---

However, it doesn't run properly. It says I'm trying to refer to a location that is out of bounds, although I don't see why.

Any help would be greatly appreciated.

Thank you.

When you do this:

Code:

---

locationTwo = Asc(textInput.Substring(i + 1, 1))

---

On the last character, you are going to be out of bounds, as you are saying take the last character and look at the next one.

For what you are doing, you can probably change your loop to:

Code:

---

For i = 0 To ((textInput.Length) - 2)

---

Code:

---

'if the entry was numbers, display error
        Else
            'entry was not letters
          MessageBox.Show("Please do not enter numbers.", "Error!")
        End If

---

Before we go further you display value is a number each time?

Quote:

---

Originally Posted by ident

Before we go further you display value is a number each time?

---

No, the instructor wanted a prompt to appear if anything other than letters was entered into the input box.

I noticed you have an i += 1 in your loop. You need to remove that. The for...next already iterates i for you.

Quote:

---

Originally Posted by Ashaelon

I noticed you have an i += 1 in your loop. You need to remove that. The for...next already iterates i for you.

---

Good catch, that would explain why it was only printing every other letter.

Focusing just on the For-Next loop, I'm thinking I would have to use another nested loop, to cycle through the rest of the word after consecutive order is found.

But how would I make the loop begin from that particular position? I'm not sure how to declare the start of the loop if "i" can't be used again.

An example of that would be

Code:

---

For j as integer = i to textInput.length - 2
    'code here
Next

---

Quote:

---

Originally Posted by Ashaelon

An example of that would be

Code:

---

For j as integer = i to textInput.length - 2
    'code here
Next

---

---

That's easier than I expected, I wasn't thinking I could simply refer back to "i."

How could I make this program record the last letter in the consecutive order, without referencing a position that's out of bounds?

Here is what I came up with. There may be a better way, but it's all I've got right now.

- Edit -

Code removed because it failed the simplest test: abcdef. Sorry for jumping the gun on that code.

Try this

Code:

---

    'declare text input as class level variable
    Dim textInput As String

    'delcare substring locations as class level variables
    Dim locationOne As Integer
    Dim locationTwo As Integer
    Dim sConsecutiveLetters As String

    Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click


        'clear read-only boxes
        lstConsecutiveLetters.Items.Clear()
        txtConcecutiveAmount.Text = ""
        sConsecutiveLetters = ""

        'if the entry was numbers, display error
        If IsNumeric(txtEntry.Text) = False Then
            'entered text is not a number, delcare variable
            textInput = txtEntry.Text.ToUpper
        Else
            'entry was not letters
            MessageBox.Show("Please do not enter numbers.", "Error!")
            'return early
            Return
        End If

        'if the entry is less than 2 letters long
        If txtEntry.Text.Length < 2 Then
            MessageBox.Show("Entered text must be at least 2 letters long!", "Error!")
            'return early
            Return
        End If

        For i = 0 To ((textInput.Length) - 2)
            Debug.WriteLine(textInput.Substring(i, 1) & vbCrLf & textInput.Substring(i + 1, 1) & vbCrLf)
            locationOne = Asc(textInput.Substring(i, 1))
            locationTwo = Asc(textInput.Substring(i + 1, 1))

            If locationTwo - locationOne = 1 Then
                If Not sConsecutiveLetters.Length > 0 Then sConsecutiveLetters = textInput.Substring(i, 1)
                sConsecutiveLetters += textInput.Substring(i + 1, 1)
            Else
                If sConsecutiveLetters.Length > 0 Then
                    For j As Integer = 0 To sConsecutiveLetters.Length - 1
                        lstConsecutiveLetters.Items.Add(sConsecutiveLetters.Substring(j, 1))
                    Next

                    sConsecutiveLetters = ""
                End If
            End If
        Next

        If sConsecutiveLetters.Length > 0 Then
            For j As Integer = 0 To sConsecutiveLetters.Length - 1
                lstConsecutiveLetters.Items.Add(sConsecutiveLetters.Substring(j, 1))
            Next
        End If
    End Sub

---

Quote:

---

Originally Posted by Ashaelon

Try this

---

That helps tremendously, thank you.

Also, while I have your attention..

what does this line do?

Code:

---

Debug.WriteLine(textInput.Substring(i, 1) & vbCrLf & textInput.Substring(i + 1, 1) & vbCrLf)

---

It's used for writing debug information to the Immediate Window so that you can see what is taking place through each step (it has other purposes too, but that the simplest to explain). I put it in to see what 2 values it was comparing (that's how i realized you had the i += 1 in the loop). If you haven't learned it yet, you can remove it (your professor might not be happy seeing it there).

Here is a link to explain more.
http://msdn.microsoft.com/en-us/libr...writeline.aspx

Will do.

Thanks again!