Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

... deleted ... 

#End Region

    Const UPPER As Integer = 9
    Const LOWER As Integer = 1
    Const gasPrice As Double = 2.0
    'Const gasToTravel As Double = 1.0
    Const MPG As Double = 20.0

    Dim inpf As IO.StreamReader
    Dim distf As IO.StreamReader
    Dim distances(30, 30) As Integer
    ' Dim junk(30, 30, 50, 40, 50, 30) As Integer
    Dim cities(30) As String
    Dim numLoc As Integer = 0
    Dim currLocIndex As Integer
    Dim randGen As New Random



    Private Function ExtractLine(ByVal text As String, ByRef line As String, ByRef startPos As Integer, ByRef foundPos As Integer) As Boolean
        ' find the next occurrence of the new line char
        foundPos = text.IndexOf(ControlChars.NewLine, startPos)
        ' check if it was found
        If foundPos = -1 Then
            Return False
        Else
            ' pull out the current line of the file
            line = text.Substring(startPos, foundPos - startPos)
            ' update the starting point for search
            startPos = foundPos + 2
            Return True
        End If
    End Function

    Private Function randPts() As Integer
        Dim rand As Integer
        rand = randGen.Next(LOWER, UPPER + 1)
        'rand = Convert.ToInt32((UPPER - LOWER + 1) * Rnd() + LOWER)
        Return rand
    End Function

    Private Function calcGasToTravel(ByVal dist(,) As Integer, ByVal startInd As Integer, ByVal endInd As Integer) As Double
        Dim gas As Double
        Dim distance As Integer
        distance = dist(startInd, endInd)
        gas = distance / MPG
        Return gas
    End Function

    Private Sub BtnQuit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnQuit.Click

        Me.Close()

    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim rand As Integer
        Dim row As Integer
        Dim col As Integer
        Dim allText As String
        Dim lineExists As Boolean
        Dim currentCity As String
        Dim start As Integer = 0
        Dim foundPos As Integer
        ' seed random number generator based on time
        Randomize()
        ' read cities in along with distances between them
        'If IO.File.Exists("cities.txt") Then
        'inpf = IO.File.OpenText("cities.txt")
        'If IO.File.Exists("morecities.txt") Then
        If My.Computer.FileSystem.FileExists("cities.txt") Then
            ' inpf = IO.File.OpenText("morecities.txt")
            ' read the file contents
            allText = My.Computer.FileSystem.ReadAllText("cities.txt")

            ' while not at end, extract line
            Do
                lineExists = ExtractLine(allText, currentCity, start, foundPos)
                If lineExists Then
                    cities(numLoc) = currentCity
                    numLoc = numLoc + 1
                End If

            Loop While lineExists And numLoc <= 30
            ' now read distances from other file
            'If IO.File.Exists("distances.txt") Then
            'distf = IO.File.OpenText("distances.txt")
            ' If IO.File.Exists("moredistances.txt") Then
            start = 0
            foundPos = 0
            Dim rowStr As String
            Dim distancesStr As String
            If My.Computer.FileSystem.FileExists("distances.txt") Then
                ' distf = IO.File.OpenText("moredistances.txt")
                distancesStr = My.Computer.FileSystem.ReadAllText("distances.txt")

                Do
                    lineExists = ExtractLine(distancesStr, rowStr, start, foundPos)
                    'Do While distf.Peek <> -1 And row < numLoc
                    'Dim rowStr As String
                    ' rowStr = distf.ReadLine() 
                    col = 0
                    Dim remStr As String
                    remStr = rowStr
                    Do While col < numLoc - 1
                        Dim commapos As Integer
                        commapos = remStr.IndexOf(",")
                        Dim currStr As String
                        currStr = remStr.Substring(0, commapos)
                        remStr = remStr.Substring(commapos + 1)
                        Dim val As Integer
                        Dim isConverted As Boolean
                        isConverted = Integer.TryParse(currStr, val)
                        If Not isConverted Then
                            MsgBox("data problem ... exiting")
                            Me.Close()
                        End If
                        ' val = Convert.ToInt32(currStr)
                        distances(row, col) = val
                        col = col + 1
                    Loop
                    ' get last distance in row
                    distances(row, col) = Convert.ToInt32(remStr)
                    row = row + 1
                Loop While lineExists And row < numLoc
            Else
                MsgBox("distance file not found, program cannot run")
            End If
        Else
            MsgBox("city file not found, program cannot run")
        End If
        ' put us in the first city
        TxtLocation.Text = cities(0)
        currLocIndex = 0
        ' fill other point values
        Dim cnt As Integer
        LstPts.Items.Add(cities(0) & ", 0")
        For cnt = 1 To numLoc - 1
            Dim line As String
            rand = randPts()
            line = cities(cnt) & ", " & rand
            LstPts.Items.Add(line)
        Next
    End Sub

    Private Sub BtnGo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnGo.Click
        Dim newPts As Integer
        Dim pts As Integer
        Dim gasAvail As Double
        Dim gasToTravel As Double
        Dim endLoc As Integer
        Dim rand As Integer
        endLoc = LstPts.SelectedIndex
        gasAvail = Convert.ToDouble(TxtGas.Text)
        If endLoc <> -1 Then
            gasToTravel = calcGasToTravel(distances, currLocIndex, endLoc)
            If gasAvail >= gasToTravel Then
                pts = Convert.ToInt32(TxtPoints.Text)
                ' determine points for going there
                Dim selectLine As String
                selectLine = LstPts.SelectedItem
                Dim commapos As Integer
                commapos = selectLine.IndexOf(",")
                Dim ptsStr As String
                ptsStr = selectLine.Substring(commapos + 1)
                newPts = Convert.ToInt32(ptsStr)
                ' move us to the new location
                TxtLocation.Text = cities(endLoc)
                currLocIndex = endLoc
                ' generate new points values
                LstPts.Items.Clear()
                Dim cnt As Integer
                For cnt = 0 To numLoc - 1
                    If cnt = endLoc Then
                        ' going to same city isn't worth any points
                        LstPts.Items.Add(cities(cnt) & ", 0")
                    Else
                        ' generate random points for going there
                        Dim line As String
                        rand = randPts()
                        line = cities(cnt) & ", " & rand
                        LstPts.Items.Add(line)
                    End If
                Next
                pts = pts + newPts
                TxtPoints.Text = Convert.ToString(pts)
                gasAvail = gasAvail - gasToTravel
                TxtGas.Text = gasAvail.ToString("n1")
            Else
                MsgBox("not enough gas to travel")
            End If

        End If

    End Sub

    Private Sub btnFuel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFuel.Click
        Dim moneyAvail As Double
        Dim gasAvail As Double
        moneyAvail = Convert.ToDouble(TxtCash.Text)
        gasAvail = Convert.ToDouble(TxtGas.Text)
        If moneyAvail >= gasPrice Then
            moneyAvail = moneyAvail - gasPrice
            gasAvail = gasAvail + 1
            TxtCash.Text = moneyAvail.ToString("n2")
            TxtGas.Text = gasAvail.ToString("n1")
        Else
            MsgBox("not enough money to buy gas")
        End If
    End Sub
End Class