11 – Enumerated Data Types, & Procedure Parameters

Session Aims & Objectives Aims, to introduce: the idea of enumerated data types passing parameters/arguments to procedures Objectives, after this week’s sessions, you should be able to: declare and use an enumerated data type use parameters in your programs to make procedures more flexible

Enumerated Data Types Often need to use numbers to represent things (coding) For example, curry: mild, medium, or hot Could store text: "mild", "medium", "hot" takes lots of space (1 byte per character) easily becomes inconsistent, e.g. "hit“ vs. “hot” Alternatively, use numbers to represent text: 1 "mild" 2 "medium" 3 "hot"

Example: Curry v1 Curry v1 Option Explicit Private Sub Form_Load() lstCurry.AddItem "Mild", 0 lstCurry.AddItem "Medium", 1 lstCurry.AddItem "Hot", 2 picCurry.FillStyle = vbSolid End Sub Private Sub lstCurry_Click() lblCurryCode.Caption = lstCurry.ListIndex lblCurryText.Caption = lstCurry.List(lstCurry.ListIndex) If lstCurry.ListIndex = 0 Then picCurry.FillColor = vbWhite ElseIf lstCurry.ListIndex = 1 Then picCurry.FillColor = vbYellow Else picCurry.FillColor = vbRed End If picCurry.Cls picCurry.Circle (1000, 750), 500 Curry v1

Example: Curry v2 Curry v2 Private Sub lstCurry_Click() Option Explicit Private Sub Form_Load() lstCurry.AddItem "Mild", 0 lstCurry.AddItem "Medium", 1 lstCurry.AddItem "Hot", 2 picCurry.FillStyle = vbSolid End Sub Private Sub lstCurry_Click() Dim CuCo As Long ' Curry code CuCo = lstCurry.ListIndex lblCurryCode.Caption = CuCo lblCurryText.Caption = lstCurry.List(CuCo) If CuCo = 0 Then picCurry.FillColor = vbWhite ElseIf CuCo = 1 Then picCurry.FillColor = vbYellow Else picCurry.FillColor = vbRed End If picCurry.Cls picCurry.Circle (1000, 750), 500 Curry v2

Example: Curry v3 Curry v3 Const Mild = 0 Const Medium = 1 Option Explicit Const Mild = 0 Const Medium = 1 Const Hot = 2 Private Sub Form_Load() lstCurry.AddItem "Mild", Mild lstCurry.AddItem "Medium", Medium lstCurry.AddItem "Hot", Hot picCurry.FillStyle = vbSolid End Sub Private Sub lstCurry_Click() Dim CuCo As Long ' Curry code CuCo = lstCurry.ListIndex lblCurryCode.Caption = CuCo lblCurryText.Caption = lstCurry.List(CuCo) If CuCo = Mild Then picCurry.FillColor = vbWhite ElseIf CuCo = Medium Then picCurry.FillColor = vbYellow Else picCurry.FillColor = vbRed End If picCurry.Cls picCurry.Circle (1000, 750), 500 Curry v3

Example: Curry v4 Curry v4 Enum TSpice Mild = 0 Medium = 1 Hot = 2 Option Explicit Enum TSpice Mild = 0 Medium = 1 Hot = 2 End Enum Private Sub Form_Load() lstCurry.AddItem "Mild", Mild lstCurry.AddItem "Medium", Medium lstCurry.AddItem "Hot", Hot picCurry.FillStyle = vbSolid End Sub Private Sub lstCurry_Click() Dim CuCo As TSpice ' Curry code CuCo = lstCurry.ListIndex lblCurryCode.Caption = CuCo lblCurryText.Caption = lstCurry.List(CuCo) If CuCo = Mild Then picCurry.FillColor = vbWhite ElseIf CuCo = Medium Then picCurry.FillColor = vbYellow Else picCurry.FillColor = vbRed End If picCurry.Cls picCurry.Circle (1000, 750), 500 Curry v4

Exercise: EDTs Create an EDT to store the following classification of height: short, average, tall Create an EDT to store the following classification of publication: book, journal Enum THeight Short = 0 Average = 1 Tall = 2 End Enum Enum TPublication Book = 0 Journal = 1 End Enum

Parameters/Arguments (what) Sometimes procedures need information Making a cup of tea: milk, and number of sugars Makes them more flexible Make cup of tea Milk Sugars

Parameters (how) Procedure Declaration Procedure Call Option Explicit Dim res As Long Private Sub Calc(Num1 As Long, Num2 As long) res = Num1 * Num2 End Sub Private Sub btnCalc_Click() Calc 5, 2 Calc 11, 15 Parameter Animation Procedure Declaration Formal parameters define name & type Procedure Call actual parameters list values in order

Example: House v1 House v1 Option Explicit Private Sub btnDraw_Click() picHouse.Cls picHouse.Line (1000, 1000)-(2000, 1750), , B picHouse.Line (1000, 1000)-(1500, 750) picHouse.Line -(2000, 1000) End Sub House v1

Example: House v1 to v2 House v1 House v2 Option Explicit Private Sub btnDraw_Click() picHouse.Cls picHouse.Line (1000, 1000)-(2000, 1750), , B picHouse.Line (1000, 1000)-(1500, 750) picHouse.Line -(2000, 1000) End Sub Option Explicit Private Sub DrawHouse() picHouse.Line (1000, 1000)-(2000, 1750), , B picHouse.Line (1000, 1000)-(1500, 750) picHouse.Line -(2000, 1000) End Sub Private Sub btnDraw_Click() picHouse.Cls DrawHouse

Example: House v2 House v2 Option Explicit Private Sub DrawHouse() picHouse.Line (1000, 1000)-(2000, 1750), , B picHouse.Line (1000, 1000)-(1500, 750) picHouse.Line -(2000, 1000) End Sub Private Sub btnDraw_Click() picHouse.Cls DrawHouse House v2

Example: House v3 House v3 Option Explicit Private Sub DrawHouse(x As Single, y As Single) picHouse.Line (x, y)-(x + 1000, y + 750), , B picHouse.Line (x, y)-(x + 500, y - 250) picHouse.Line -(x + 1000, y) End Sub Private Sub btnDraw_Click() picHouse.Cls DrawHouse 1000, 1000 DrawHouse 2500, 1000 DrawHouse 4000, 1000 House v3

Exercise: Parameters Given the following declaration: What will the following put in lblOutput? Sub thing(Num1 As Long, Num2 As Long, Num3 As Long) Dim tmpOutput As Long tmpOutput = (Num1 + Num2) * Num3 lblOutput.Caption = tmpOutput End Sub thing 2, 3, 6 thing 6, 3, 2 thing 20, 5, 2 30 18 50

Example: Till v1 Till v1 Option Explicit Dim SubTotal As Double Dim Total As Double Private Sub btnEquals_Click() Dim price As Double Dim quantity As Double price = Val(Me.txtPrice.Text) quantity = Val(Me.txtQuantity.Text) SubTotal = price * quantity lblSubTotal.Caption = "£" & SubTotal End Sub Private Sub btnAdd_Click() Total = Total + SubTotal lblTotal.Caption = "£" & Total Private Sub btnUndo_Click() Total = Total - SubTotal Till v1

Example: Till v2 amount: Double TotalAdd Till v2 Option Explicit Dim SubTotal As Double Dim Total As Double Private Sub TotalAdd(amount As Double) Total = Total + amount Me.lblTotal.Caption = "£" & Total End Sub Private Sub btnEquals_Click() Dim price As Double Dim quantity As Double price = Val(Me.txtPrice.Text) quantity = Val(Me.txtQuantity.Text) SubTotal = price * quantity lblSubTotal.Caption = "£" & SubTotal Private Sub btnAdd_Click() TotalAdd SubTotal Private Sub btnUndo_Click() TotalAdd -SubTotal amount: Double TotalAdd Till v2

Example: Heart Rate v3 Option Explicit Dim HR(0 To 6) As Long Private Sub Form_Load() HR(0) = 134 HR(1) = 127 HR(2) = 139 HR(3) = 155 HR(4) = 143 HR(5) = 151 HR(6) = 141 End Sub Private Sub DrawHR() Dim i As Long picMain.Cls For i = 0 To 6 picMain.Line -(i * 500, HR(i) * 10) Next Private Sub btnDraw_Click() DrawHR

Example: Heart Rate v4 Option Explicit Dim HR(0 To 6) As Long Private Sub Form_Load() HR(0) = 134 HR(1) = 127 HR(2) = 139 HR(3) = 155 HR(4) = 143 HR(5) = 151 HR(6) = 141 End Sub Private Sub DrawHR(picTemp As PictureBox) Dim i As Long picTemp.Cls For i = 0 To 6 picTemp.Line -(i * 500, HR(i) * 10) Next Private Sub btnDraw_Click() DrawHR Me.picMain1 DrawHR Me.picMain2