Apartment Rent (VB Source Code for Beginners)

    'Made by Junkie
    '10/13/2013
    Option Strict On
    Public Class frmRentList

    #Region "Constant Declarations"

        Private Const FLOOR_NUM_MIN As Integer = 3
        Private Const FLOOR_NUM_MAX As Integer = 20
        Private Const RENT_LOWER_LIMIT As Integer = 1000
        Private Const RENT_UPPER_LIMIT As Integer = 2500

    #End Region

    #Region "Form Level Variable Declarations"
        Private numFloors As Integer
        Private requestedFloor As Integer
        Private rentList() As Integer
    #End Region

    #Region "Validating Event Handlers"
        'here we are validating the text boxes for name and the number of floors
       Private Sub NameValidatingEvent(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles _
                                                                                                               txtName.Validating,
                                                                                                               txtNumFloors.Validating
            Dim txtbox As TextBox = CType(sender, TextBox)
            Dim datadescription As String = String.Empty
            If sender Is txtName Then
                datadescription = "Name"
            ElseIf sender Is txtNumFloors Then
                datadescription = "Number of Floors"
            End If
            e.Cancel = ValidateStringInput(datadescription, txtbox.Text)
        End Sub
        Private Sub NumberValidatingEvent(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles _
            txtNumFloors.Validating
            Const FLOORS_LOWER_LIMIT As Integer = 3
            Const FLOORS_UPPER_LIMIT As Integer = 20
            Dim txtBox As TextBox = CType(sender, TextBox)
            If sender Is txtNumFloors Then
                e.Cancel = ValidateNumberInput("Number of Floors", txtBox.Text, FLOORS_LOWER_LIMIT, FLOORS_UPPER_LIMIT, numFloors)
                btnRentList.Enabled = Not (e.Cancel)
            End If
            If e.Cancel Then
                txtBox.Clear()
            End If
        End Sub
    #End Region
    #Region "Utility Modules"
        Private Function ValidateStringInput(ByVal dataDescription As String, ByVal strInput As String) As Boolean
            Dim invalid As Boolean = True
            If Not String.IsNullOrEmpty(strInput) Then
                invalid = False
            Else
                MessageBox.Show(dataDescription & " must be provided", "Empty " & dataDescription, MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                invalid = True
            End If
            Return invalid
        End Function
        Private Function ValidateNumberInput(ByVal dataType As String, ByVal strInput As String, _
                                              ByVal min As Integer, ByVal max As Integer, _
                                              ByRef value As Integer) As Boolean
            Dim invalid As Boolean = True

            If IsNumeric(strInput) Then
                value = Integer.Parse(strInput)
                If value >= min AndAlso value <= max Then
                    invalid = False
                Else
                    MessageBox.Show(dataType & " must be between " & min & " and " & max & "--try again", "Invalid " & dataType, MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                    invalid = True
                End If
            Else
                MessageBox.Show(dataType & " must be between " & min & " and " & max & "--try again", "Invalid " & dataType, MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                invalid = True
            End If
            Return invalid
        End Function
        Private Sub ClearFields()
            txtName.Clear()
            txtNumFloors.Clear()
            txtFloorRequest.Clear()
            lstRents.Items.Clear()
            lblRentResults.Visible = False
            btnRentList.Enabled = False
            btnGetFloorRent.Enabled = False
        End Sub
        'getting the rent data
       Private Sub CollectFloorRentData()
            lstRents.Items.Add("Floor" & vbTab & "Rent")
            If numFloors > 0 Then
                ReDim rentList(numFloors - 1)
                For i As Integer = 0 To rentList.Count - 1
                    rentList(i) = GetData("Floor Rent: ", RENT_LOWER_LIMIT, RENT_UPPER_LIMIT)
                    addtodisplaylist(i + 1, rentList(i))
                Next
            End If
        End Sub
        'displaying the floor numbers and rent for each floor
       Private Sub addtodisplaylist(ByVal numfloors As Integer, ByVal rentlist As Integer)
            lstRents.Items.Add(numfloors.ToString & vbTab _
                               & rentlist.ToString)
        End Sub
        Private Function GetData(ByVal dataDescription As String, ByVal lowerLimit As Integer, ByVal upperLimit As Integer) As Integer
            'getting floor level data
           Dim value As Integer
            Dim response As String
            Do
                response = InputBox("Enter the number of " & dataDescription & "(" & lowerLimit.ToString & " to " & upperLimit.ToString & "): ")
                ValidateNumberInput(dataDescription, response, lowerLimit, upperLimit, value)
            Loop Until (value >= lowerLimit AndAlso value <= upperLimit)
            Return value
        End Function
        'finding and verifying the user specified floor
       Private Sub findfloordata()
            Dim floorrequest As Integer = CInt(txtFloorRequest.Text)
            If floorrequest <= numFloors Then
                DisplaySummaryData(rentList(floorrequest - 1))
            Else
                MessageBox.Show("Floor request must be between 1 and " & numFloors, "Error" & MessageBoxButtons.OK & MessageBoxIcon.Exclamation)
            End If
        End Sub
        'this is where the results are displayed in the rent total label

        Private Sub DisplaySummaryData(ByVal rentlist As Integer)
            lblRentResults.Visible = True
            lblRentResults.Text = ("Apartment Name " & txtName.Text & vbNewLine _
                                & "Floor Number " & txtFloorRequest.Text & vbNewLine _
                                & "Rent " & rentlist)
        End Sub
    #End Region
        Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnExit.Click
            'exit button
           Me.Close()
        End Sub
        Private Sub frmRentList_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        End Sub
        Private Sub btnRentList_Click(sender As Object, e As EventArgs) Handles btnRentList.Click
            'displaying rent in the list box
           CollectFloorRentData()

        End Sub
        Private Sub btnGetFloorRent_Click(sender As Object, e As EventArgs) Handles btnGetFloorRent.Click
            'displaying rent total for given floor
           findfloordata()
        End Sub
        Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
            'clear button
           Me.lblRentResults.Text = ""
            Me.lstRents.Text = ""
            Me.txtFloorRequest.Text = ""
            Me.txtName.Text = ""
            Me.txtNumFloors.Text = ""
        End Sub
    End Class