Purpose of the program: The Windows application opens a text file with the populations of the 10 largest cities in the united states. The user selects a city and displays the population for next five years with a projected 3% growth per year. A menu selection also can show the top 10 cities and their present population on a second windows form object.
I am having trouble getting the projected growth to show in the list box. Here is my code
Option Strict On
Public Class frmProjectedPopulation
'Class level variables
Private _intYears As Integer = 5
Public Shared _intSizeOfArray As Integer = 9
Public Shared _strCities(_intSizeOfArray) As String
Public Shared _intPopulation(_intSizeOfArray) As Integer
Private Sub frmProjectedPopulation_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
' The frmProjectedPopulation load event reast the cities text file and fills the ComboBox object with the Cities
' Initialize an instance of the StreamReader object and declare variables
Dim objReader As IO.StreamReader
Dim strLocationAndNameOfFile As String = "G:\CPC240\Chapter 09\Chapter 09\CaseProjects\cities.txt"
Dim intCount As Integer = 0
Dim intFill As Integer
Dim strFileError As String = " The file is not available. Restart when the file is available."
' Verify the file exists
If IO.File.Exists(strLocationAndNameOfFile) Then
objReader = IO.File.OpenText(strLocationAndNameOfFile)
' Read the file line by line until the file is completed
Do While objReader.Peek <> -1
_strCities(intCount) = objReader.ReadLine()
_intPopulation(intCount) = CInt(objReader.ReadLine())
intCount += 1
Loop
objReader.Close()
' The ComboBox object is filled with the Names of the Cities
For intFill = 0 To (_strCities.Length - 1)
cboCityName.Items.Add(_strCities(intFill))
Next
Else
MsgBox(strFileError, , "Error")
Close()
End If
End Sub
Private Sub btnComputeExpectedGrowth_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnComputeExpectedGrowth.Click
' This button click event calls the Growth sub procedures
' Declare variables
Dim intSelectedCity As Integer
Dim strMissingSelection As String = "Missing Selection"
Dim strSelectCityError As String = "Select a City"
' If a ComboBox object is selected, call the Growth procedure
If Me.cboCityName.SelectedIndex >= 0 Then
intSelectedCity = cboCityName.SelectedIndex
FutureGrowth(intSelectedCity)
Else
MsgBox(strSelectCityError, , strMissingSelection)
End If
End Sub
Private Sub FutureGrowth(ByVal intCity As Integer)
' This sub procedure diplays the current population and also the population for the next 5 years for the city selected
' Declare variables
Dim decFutureGrowth As Decimal
Dim decPopulationTotal As Decimal
Dim strSelectCity As String = " The present population is "
MakeObjectsVisible()
lblPopulation.Text = strSelectCity & _intPopulation(_intSizeOfArray)
lstExpectedGrowth.Text = CStr(decFutureGrowth)
decFutureGrowth = CDec(_intPopulation(intCity) * 0.03)
' The loop repeats for 5 years
For decFutureGrowth = 1 To _intYears
'Accumulates the future population
decPopulationTotal += decFutureGrowth
' Displays the future population amounts
lstExpectedGrowth.Items.Add(decFutureGrowth.ToString())
decPopulationTotal -= decFutureGrowth
Next
End Sub
Private Sub MakeObjectsVisible()
' This procedure displays the objects after a city is selected
lblPopulation.Visible = True
lblExpectedGrowth.Visible = True
lstExpectedGrowth.Visible = True
' Previous data removed
lstExpectedGrowth.Items.Clear()
End Sub
Private Sub mnuDisplayPresentPopulation_Click(sender As System.Object, e As System.EventArgs) Handles mnuDisplayPresentPopulation.Click
' The mnuDisplayPresentPopulation click event creates an instance of the frmCurrentLargestCities
Dim frmSecond As New frmCurrentLargestCities
' Hide this form and show the Display Inventory form
Hide()
frmSecond.ShowDialog()
End Sub
Private Sub mnuClear_Click(sender As System.Object, e As System.EventArgs) Handles mnuClear.Click
' The mnuClear click event clears and resets the form
cboCityName.SelectedIndex = -1
lblExpectedGrowth.Visible = False
lblPopulation.Visible = False
lstExpectedGrowth.Visible = False
lstExpectedGrowth.Items.Clear()
End Sub
Private Sub mnuExit_Click(sender As System.Object, e As System.EventArgs) Handles mnuExit.Click
' The mnuExit click event closes the application
Application.Exit()
End Sub
End Class
