Mark Dixon, SoCCE SOFT 131Page 1 10 – Enumerated Data Types & Procedure Parameters

Mark Dixon, SoCCE SOFT 131Page 2 Session Aims & Objectives Aims, to introduce: –the idea of enumerated data types –passing parameters/arguments to procedures –control arrays 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 –use control arrays

Mark Dixon, SoCCE SOFT 131Page 3 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"

Mark Dixon, SoCCE SOFT 131Page 4 Example: 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 End Sub Curry v1

Mark Dixon, SoCCE SOFT 131Page 5 Example: Curry v2 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 End Sub Curry v2

Mark Dixon, SoCCE SOFT 131Page 6 Example: Curry v3 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 End Sub Curry v3

Mark Dixon, SoCCE SOFT 131Page 7 Example: Curry v4 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 End Sub Curry v4

Mark Dixon, SoCCE SOFT 131Page 8 Questions: 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

Mark Dixon, SoCCE SOFT 131Page 9 Parameters in Event Procedures Provide us with information about event –e.g. if mouse was clicked where was it (x, and y co-ordinates) which mouse button was pressed which keyboard buttons were pressed ([Shift] / [Ctrl])

Mark Dixon, SoCCE SOFT 131Page 10 Example: Draw Option Explicit Private Sub picDraw_MouseDown( Button As Integer, Shift As Integer, X As Single, Y As Single ) If Button = 1 Then picDraw.PSet (X, Y) End If End Sub Private Sub picDraw_MouseMove( Button As Integer, Shift As Integer, X As Single, Y As Single ) If Button = 1 Then picDraw.Line -(X, Y) End If End Sub Parameters: –appear in the brackets of a procedure definition horizontal & vertical mouse co-ordinates mouse button keyboard [Shift] [Ctrl] keys

Mark Dixon, SoCCE SOFT 131Page 11 Parameters/Arguments (what) Sometimes our own procedures need information –Making a cup of tea: milk, and number of sugars Makes them more flexible Make cup of tea Milk Sugars

Mark Dixon, SoCCE SOFT 131Page 12 Parameters (how) Procedure Declaration –Formal parameters define name & type Procedure Call –actual parameters list values in order 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 End Sub

Mark Dixon, SoCCE SOFT 131Page 13 Parameters (how)

Mark Dixon, SoCCE SOFT 131Page 14 Example: 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

Mark Dixon, SoCCE SOFT 131Page 15 Example: House v1 to 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 End Sub House v1House v2

Mark Dixon, SoCCE SOFT 131Page 16 Example: 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 End Sub House v2

Mark Dixon, SoCCE SOFT 131Page 17 Example: House v3 Option Explicit Private Sub DrawHouse(x As Single, y As Single) picHouse.Line (x, y)-(x , y + 750),, B picHouse.Line (x, y)-(x + 500, y - 250) picHouse.Line -(x , y) End Sub Private Sub btnDraw_Click() picHouse.Cls DrawHouse 1000, 1000 DrawHouse 2500, 1000 DrawHouse 4000, 1000 End Sub House v3

Mark Dixon, SoCCE SOFT 131Page 18 Questions: 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,

Mark Dixon, SoCCE SOFT 131Page 19 Example: 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 End Sub Private Sub btnUndo_Click() Total = Total - SubTotal lblTotal.Caption = "£" & Total End Sub Till v1

Mark Dixon, SoCCE SOFT 131Page 20 amount: Double Example: 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 End Sub Private Sub btnAdd_Click() TotalAdd SubTotal End Sub Private Sub btnUndo_Click() TotalAdd -SubTotal End Sub TotalAdd Till v2

Mark Dixon, SoCCE SOFT 131Page 21 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 End Sub Private Sub btnDraw_Click() DrawHR End Sub

Mark Dixon, SoCCE SOFT 131Page 22 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 End Sub Private Sub btnDraw_Click() DrawHR Me.picMain1 DrawHR Me.picMain2 End Sub

Mark Dixon, SoCCE SOFT 131Page 23 Control Arrays Several controls have same name Distinguished by unique index Very similar to a variable array Makes it easier to do same thing to all controls – using for loop

Mark Dixon, SoCCE SOFT 131Page 24 Example: Ships - UI lblMooringID picMain(3) picMain(1) picMain(2) picMain(0) Four controls share same name (picMain): Ships

Mark Dixon, SoCCE SOFT 131Page 25 Example: Ships - Code Option Explicit Sub Draw() Dim i As Long For i = 0 To 3 picMain(i).DrawWidth = 3 picMain(i).Line (1000, 1000)-(2000, 1000) picMain(i).Line -Step(-200, 200) picMain(i).Line -Step(-600, 0) picMain(i).Line -Step(-200, -200) Next End Sub Private Sub picMain_Click(Index As Integer) lblMooringID.Caption = Index Draw End Sub

Mark Dixon, SoCCE SOFT 131Page 26 Control Arrays - How To create a control array, either: –Create a control with the same name as an existing control (VB will ask you if you want to create a control array) Or: –Create a control and type a value into its index property (e.g. 0)

Mark Dixon, SoCCE SOFT 131Page 27 Container Controls Some controls can contain other controls: –Picture boxes –Frames The container (parent) control clips the contained (child) controls –The child controls will not be displayed outside the boundary of their parent

Mark Dixon, SoCCE SOFT 131Page 28 Example – Pic Container The inner picture box is clipped: picInner picOuter

Mark Dixon, SoCCE SOFT 131Page 29 Tutorial Exercise: Curry LEARNING OBJECTIVE: to understand enumerated data types Task 1: Get the Curry examples from the lecture working. Task 2: Modify your code – add an extra category called ‘Blazing’ with a code value of 3.

Mark Dixon, SoCCE SOFT 131Page 30 Tutorial Exercise: Draw LEARNING OBJECTIVE: –use parameters provided by event procedures Task 1: Get the Draw example (from the lecture) working. Task 2: Modify your code – allow the user to rub out (paint in the background colour) using the right mouse button. Task 3: Modify your code – allow the user to use a thicker line by holding down the [ctrl] button on the keyboard

Mark Dixon, SoCCE SOFT 131Page 31 Tutorial Exercise: House LEARNING OBJECTIVE: –use parameters in your own procedures, to make them more flexible (general purpose) Task 1: Get the House examples (versions 1, 2, and 3) from the lecture working. Task 2: Modify your code – add code that draws a door and a window for each house. Task 3: Modify your code – add code that draws 10 small houses. Hint: use a for loop (rather than simply copying the procedure calls)

Mark Dixon, SoCCE SOFT 131Page 32 Tutorial Exercise: Till LEARNING OBJECTIVE: –use parameters in your own procedures, to make them more flexible (general purpose) Task 1: Get the Till examples (versions 1 and 2) from the lecture working. Task 2: Modify your code – add code that clears all data when the clear button is clicked. Task 3: Modify your code – create a procedure to calculate and display the sub total.

Mark Dixon, SoCCE SOFT 131Page 33 Tutorial Exercise: Heart Rate LEARNING OBJECTIVE: –use parameters in your own procedures, to make them more flexible (general purpose) Task 1: Get the Heart Rate examples (versions 3 and 4) from the lecture working. Task 2: Modify your code – use additional parameters to control the horizontal and vertical sizes of the graphs (so that the two graphs can be different sizes).