This document contains code for a utility cost calculator application. It includes code to: 1. Validate user input values are within expected ranges for different appliances. 2. Calculate total daily cost by multiplying cost per kWh, power usage, and hours of use. 3. Populate dropdown lists, display default values, and reset forms for new calculations.

1. 1C:UsersMichelleDocumentsVisual Studio 2013... Cost CalculatorUtility Cost CalculatorAppCalc.vb
' Michelle John
' May 11, 2015
' POS 408
' Dr. Bill Spees
Imports System.IO
Public Class AppCalc
Dim strApplianceArray(1) As String
Dim dblDefaultValueArray(1) As Double
Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
ResetTheForm()
End Sub
Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnExit.Click
' Close the form
Me.Close()
End Sub
Private Sub txtCostKWh_Leave(sender As Object, e As EventArgs) Handles txtCostKWh.Leave
' Values determined by current prices of electricity at
' http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_5_6_a
' Cost in Hawaii is the highest at $0.3334 as of this date.
' Cost in Washington is the lowest at $0.0813 as of this date.
Const dblMIN_COST_PER_KWH = 0.05
Const dblMAX_COST_PER_KWH = 0.35
ResetErrorMessage()
' Checks if the value is in range and if not puts cursor back in the text box
If Not InRange(txtCostKWh.Text, dblMIN_COST_PER_KWH, dblMAX_COST_PER_KWH) Then
txtCostKWh.Focus()
End If
End Sub
Private Sub txtPower_Leave(sender As Object, e As EventArgs) Handles txtPower.Leave
ResetErrorMessage()
' Ranges determined by the values found on this site:
' http://www.daftlogic.com/information-appliance-power-consumption.htm
' Ranges for appliances not on that site extrapolated from values given in classroom
' texts.
Select Case cbxApplianceList.Text
' REFRIGERATOR-----------------------------------------------------------------
Case "Refrigerator"
Const dblMIN_POWER = 0.1
Const dblMAX_POWER = 0.5
' Checks if the value is in range and if not puts cursor back in the text box
If Not InRange(txtPower.Text, dblMIN_POWER, dblMAX_POWER) Then
txtPower.Focus()

2. 2C:UsersMichelleDocumentsVisual Studio 2013... Cost CalculatorUtility Cost CalculatorAppCalc.vb
End If
' HAIR DRYER---------------------------------------------------------------
Case "Hair Dryer"
Const dblMIN_POWER = 1.0
Const dblMAX_POWER = 1.5
' Checks if the value is in range and if not puts cursor back in the text box
If Not InRange(txtPower.Text, dblMIN_POWER, dblMAX_POWER) Then
txtPower.Focus()
End If
' DEEP FREEZE-------------------------------------------------------------
Case "Deep Freeze"
Const dblMIN_POWER = 0.1
Const dblMAX_POWER = 0.25
' Checks if the value is in range and if not puts cursor back in the text box
If Not InRange(txtPower.Text, dblMIN_POWER, dblMAX_POWER) Then
txtPower.Focus()
End If
' MICROWAVE----------------------------------------------------------------
Case "Microwave"
Const dblMIN_POWER = 0.5
Const dblMAX_POWER = 1.5
' Checks if the value is in range and if not puts cursor back in the text box
If Not InRange(txtPower.Text, dblMIN_POWER, dblMAX_POWER) Then
txtPower.Focus()
End If
' COMPUTER------------------------------------------------------------------
Case "Computer"
Const dblMIN_POWER = 0.04
Const dblMAX_POWER = 0.2
' Checks if the value is in range and if not puts cursor back in the text box
If Not InRange(txtPower.Text, dblMIN_POWER, dblMAX_POWER) Then
txtPower.Focus()
End If
' FAN---------------------------------------------------------------------
Case "Fan"
Const dblMIN_POWER = 0.005
Const dblMAX_POWER = 0.03
' Checks if the value is in range and if not puts cursor back in the text box
If Not InRange(txtPower.Text, dblMIN_POWER, dblMAX_POWER) Then
txtPower.Focus()
End If

3. 3C:UsersMichelleDocumentsVisual Studio 2013... Cost CalculatorUtility Cost CalculatorAppCalc.vb
' WASHER-------------------------------------------------------------------
Case "Washer"
Const dblMIN_POWER = 0.4
Const dblMAX_POWER = 0.6
' Checks if the value is in range and if not puts cursor back in the text box
If Not InRange(txtPower.Text, dblMIN_POWER, dblMAX_POWER) Then
txtPower.Focus()
End If
' ELSE---------------------------------------------------------------------
Case Else
' Unique error message
lblResults.ForeColor = Color.Red
lblResults.BackColor = Color.White
lblResults.Text = "Please select an appliance from the pull down list."
End Select
End Sub
Private Sub txtHoursPerDay_Leave(sender As Object, e As EventArgs) _
Handles txtHoursPerDay.Leave
ResetErrorMessage()
Const dblMIN_HOURS = 0.0
Const dblMAX_HOURS = 24.0
' Checks if the value is in range and if not puts cursor back in the text box
If Not InRange(txtHoursPerDay.Text, dblMIN_HOURS, dblMAX_HOURS) Then
txtHoursPerDay.Focus()
End If
End Sub
Private Function InRange(ByVal strInputString As String,
ByVal dblMinValue As Double,
ByVal dblMaxValue As Double) As Boolean
' Tests entered values to determine if they fall within the proper range.
' Returns True if the value is within range, False if the value is not within range.
Dim dblEnteredValue As Double
If Double.TryParse(strInputString, dblEnteredValue) Then
If (dblEnteredValue < dblMinValue) Or (dblEnteredValue > dblMaxValue) Then
ShowErrorMessage(dblMinValue, dblMaxValue)
Return False
Else
Return True
End If
Else

4. 4C:UsersMichelleDocumentsVisual Studio 2013... Cost CalculatorUtility Cost CalculatorAppCalc.vb
ShowErrorMessage(dblMinValue, dblMaxValue)
Return False
End If
End Function
Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click
Dim dblCost As Double ' Used to make it easier to read the code
Dim ApplianceOutputList As ListViewItem
Dim blnFound As Boolean = False
Dim intCounter As Integer = 0
' Checks to make sure all values are numeric to prevent calculation errors
If IsNumeric(txtCostKWh.Text) And _
IsNumeric(txtPower.Text) And _
IsNumeric(txtHoursPerDay.Text) And _
IsNumeric(txtCostPerGallon.Text) And _
IsNumeric(txtGallonsPerHour.Text) Then
dblCost = CalculateTotalCostPerDay(CDbl(txtCostKWh.Text), _
CDbl(txtPower.Text), _
CDbl(txtHoursPerDay.Text), _
CDbl(txtCostPerGallon.Text), _
CDbl(txtGallonsPerHour.Text))
' Updates the list with the values entered by the user
lstApplianceOutputList.BeginUpdate()
ApplianceOutputList = lstApplianceOutputList.Items.Add(cbxApplianceList.Text)
ApplianceOutputList.SubItems.Add(txtHoursPerDay.Text)
ApplianceOutputList.SubItems.Add(dblCost.ToString("c"))
lstApplianceOutputList.Update()
lstApplianceOutputList.EndUpdate()
RunningTotal()
Else
lblResults.ForeColor = Color.Red
lblResults.BackColor = Color.White
lblResults.Text = "Please make sure all values you have entered are numeric."
End If
' Resets the form to get ready for the next set of inputs
cbxApplianceList.Text = "Refrigerator"
txtHoursPerDay.Text = String.Empty
ResetWasherInfo()
gbxAppList.Focus()
' Finds the default value for "Refrigerator" and populates the txtPower field with the
' appropriate value
While Not blnFound
If strApplianceArray(intCounter) = "Refrigerator" Then
txtPower.Text = dblDefaultValueArray(intCounter).ToString
blnFound = True
End If
intCounter += 1
End While

5. 5C:UsersMichelleDocumentsVisual Studio 2013... Cost CalculatorUtility Cost CalculatorAppCalc.vb
End Sub
Private Sub RunningTotal()
' Adds the values in the Cost Per Day column
Dim dblRunningTotal As Double = 0.0
For i As Integer = 0 To (lstApplianceOutputList.Items.Count() - 1)
' Gets the values held within the Cost Per Day column and adds them
dblRunningTotal += CDbl(lstApplianceOutputList.Items(i).SubItems.Item(2).Text)
Next
' Updates lblTotalCost
lblTotalCost.Text = dblRunningTotal.ToString("c")
End Sub
Private Sub ShowErrorMessage(ByVal dblMinValue As Double, _
ByVal dblMaxValue As Double)
' Error message
lblResults.ForeColor = Color.Red
lblResults.BackColor = Color.White
lblResults.Text = "Please enter a numeric value greater than " & dblMinValue.ToString &
" and less than " & dblMaxValue.ToString & "."
End Sub
Private Sub ResetErrorMessage()
' Resets the colors back to default
lblResults.ForeColor = SystemColors.ControlText
lblResults.BackColor = SystemColors.Control
lblResults.Text = String.Empty
End Sub
Private Function CalculateTotalCostPerDay(ByVal dblCost As Double, _
ByVal dblPower As Double, _
ByVal dblHours As Double, _
ByVal dblGalCost As Double, _
ByVal dblGalHour As Double) As Double
' Total cost per day calculated as Cost per kWH * Power used per hour * hours used.
' When no water is used the value in the right side of the expression will always be zero.
Return (dblCost * dblPower * dblHours) + (dblGalCost * dblGalHour * dblHours)
End Function
Private Sub ResetTheForm()
Dim blnFound As Boolean = False
Dim intCounter As Integer = 0
' Reset the form
cbxApplianceList.Text = "Refrigerator"
txtCostKWh.Text = String.Empty
txtHoursPerDay.Text = String.Empty
ResetWasherInfo()
lblResults.Text = String.Empty
lblTotalCost.Text = "0.00"
lstApplianceOutputList.Items.Clear()
gbxAppList.Focus()

6. 6C:UsersMichelleDocumentsVisual Studio 2013... Cost CalculatorUtility Cost CalculatorAppCalc.vb
' Finds the default value for "Refrigerator" and populates the txtPower field
' with the appropriate value
While Not blnFound
If strApplianceArray(intCounter) = "Refrigerator" Then
txtPower.Text = dblDefaultValueArray(intCounter).ToString
blnFound = True
End If
intCounter += 1
End While
End Sub
Private Sub ResetWasherInfo()
' Resets the labels and text boxes related to the choice of "Washer"
lblGallonCostLabel.Visible = False
lblGallonsUsedLabel.Visible = False
lblDollarSign2.Visible = False
lblGalPerHour.Visible = False
txtCostPerGallon.Visible = False
txtCostPerGallon.Text = "0.00"
txtGallonsPerHour.Visible = False
txtGallonsPerHour.Text = "0.0"
End Sub
Private Sub cbxApplianceList_SelectedValueChanged(sender As Object, e As EventArgs) _
Handles cbxApplianceList.SelectedValueChanged
Dim blnFound As Boolean = False
Dim intCounter As Integer = 0
' Looks through the array strApplianceArray, finds the appliance,
' and sets a default value to txtPower.text
While Not blnFound
If strApplianceArray(intCounter) = cbxApplianceList.Text Then
txtPower.Text = dblDefaultValueArray(intCounter).ToString
blnFound = True
End If
intCounter += 1
End While
' Shows fields related to the choice of "Washer"
If cbxApplianceList.Text = "Washer" Then
lblGallonCostLabel.Visible = True
lblGallonsUsedLabel.Visible = True
lblDollarSign2.Visible = True
lblGalPerHour.Visible = True
txtCostPerGallon.Visible = True
txtGallonsPerHour.Visible = True
Else
ResetWasherInfo()

7. 7C:UsersMichelleDocumentsVisual Studio 2013... Cost CalculatorUtility Cost CalculatorAppCalc.vb
End If
End Sub
Private Sub txtCostPerGallon_Leave(sender As Object, e As EventArgs) _
Handles txtCostPerGallon.Leave
' Costs constant values based on cost of author's water.
Const dblMIN_COST = 0.01
Const dblMAX_COST = 0.15
ResetErrorMessage()
InRange(txtCostPerGallon.Text, dblMIN_COST, dblMAX_COST)
End Sub
Private Sub txtGallonsPerHour_Leave(sender As Object, e As EventArgs) _
Handles txtGallonsPerHour.Leave
' Gallons of water used based on values found at
' http://www.home-water-works.org/indoor-use/clothes-washer
Const dblMIN_GALLONS_USED = 12
Const dblMAX_GALLONS_USED = 45
ResetErrorMessage()
InRange(txtGallonsPerHour.Text, dblMIN_GALLONS_USED, dblMAX_GALLONS_USED)
End Sub
Private Sub AppCalc_Load(sender As Object, e As EventArgs) _
Handles MyBase.Load
' Fills an array of appliance names and a parallel array of default
' values from an external file
Dim fileReader As StreamReader
Dim intArrayElement As Integer
intArrayElement = 0
fileReader = File.OpenText("DefaultValues.txt")
' Counts the number of elements needed in the parallel arrays
While Not fileReader.EndOfStream
fileReader.ReadLine()
fileReader.ReadLine()
intArrayElement += 1
End While
fileReader.Close()
' Resizes arrays based on the number of records in the data file
ReDim strApplianceArray(intArrayElement - 1)
ReDim dblDefaultValueArray(intArrayElement - 1)
fileReader = File.OpenText("DefaultValues.txt")
For i As Integer = 0 To (intArrayElement - 1)
strApplianceArray(i) = fileReader.ReadLine()
dblDefaultValueArray(i) = CDbl(fileReader.ReadLine())

8. 8C:UsersMichelleDocumentsVisual Studio 2013... Cost CalculatorUtility Cost CalculatorAppCalc.vb
Next
fileReader.Close()
End Sub
Private Sub btnExport_Click(sender As Object, e As EventArgs) _
Handles btnExport.Click
' Exports the data in the lstApplianceOutputList and the total
' cost into a txt file
Dim fileWriter As StreamWriter
Dim strTemp As String 'Used to format the output
Dim strTempApp As String 'Used to format the output
Dim strTempHours As String 'Used to format the output
Dim strTempCost As String 'Used to format the output
fileWriter = File.AppendText("ExportFile.txt")
' Writes a header to the text file
fileWriter.WriteLine(String.Format("{0, 15} {1, 15} {2, 15}", _
"Appliance", "Hours Used", "Cost per Day"))
' Runs through lstApplianceOutputList, reads the values into the temp variables,
' formats the results, and then writes the formated results into the text file
For i As Integer = 0 To (lstApplianceOutputList.Items.Count - 1)
strTempApp = lstApplianceOutputList.Items(i).Text
strTempHours = lstApplianceOutputList.Items(i).SubItems(1).Text
strTempCost = lstApplianceOutputList.Items(i).SubItems(2).Text
strTemp = String.Format("{0, -15} {1, 15} {2, 15}", _
strTempApp, strTempHours, strTempCost)
fileWriter.WriteLine(strTemp)
Next
' Adds the total cost to the text file
fileWriter.WriteLine("-----------------")
fileWriter.WriteLine("Total Cost")
fileWriter.WriteLine(lblTotalCost.Text)
fileWriter.WriteLine()
fileWriter.Close()
' Let's the user know something happened when the button was clicked
lblResults.Text = "File has been exported to ExportFile.txt."
End Sub
End Class