Chapter 5' Menus, Sub Procedures, and Sub Functions

1
Chapter 5. Menus, Sub Procedures, and Sub
Functions

• Menus
• Menu Commands
• Use Menu Editor to create Menus
• The Caption the words you want to appear on the
  screen
• The Name the name of menu control
• Naming Standards mnu
• Submenus another list of menus under a menu

2
Common Dialog Boxes

• Use a set of predefined standard dialog boxes
  like colors and fonts, printing, opening, and
  saving
• Invisible when your program runs
• How to set up Common Dialog Box
• Open the Project menu
• Choose Components
• Check Microsoft Common Dialog Control 6.0

3

• Show Method General Form
• object.ShowMethod
• Method ShowOpen, ShowSave, ShowColor, ShowFont,
  ShowPrint
• Color Dialog Box
• dlgCommon.ShowColor Display the Color dialog box
• Using default color
• dlgCommon.ShowColor
• frmMain.BackColor dlgCommon.Color
• Using currently selected color
• With dlgCommon
• .Flags cdlCCRGBInit Initialize the dialog box
• .Color frmMain.BackColor Set initial color
• .ShowColor Display dialog box and get color
• End With
• frmMain.BackColor dlgCommon.Color Set color of
  form

4

• Font Dialog Box
• Font Property of Common Dialog Control
• FontBold, FontItalic, FontName, FontSize,
  FontStrikeThru, FontUnderline
• The value of the Flags property
  cdlCFScreenFonts, cdlCFPrinterFonts, cdlCFBoth
• With dlgCommon
• .Flags cdlCFScreenFonts
• .ShowFont
• End With
• With lblEmployee.Font
• .Name dlgCommon.FontName
• .Bold dlgCommon.FontBold
• End With

5
Writing General Procedures

• Useful in breaking down large sections of code
  into smaller units that perform a specific task
• Useful either a command button or a menu option
  to do the same thing
• Can be called from either a command button or a
  menu option

6
Passing Values to Procedures

• Passing Arguments ByVal
• Sends a copy of the arguments value to the
  procedure so that the procedure cannot alter the
  original value
• The number of arguments, their sequence, and
  their data types must match in both locations,
  but not the names
• Passing Arguments ByRef
• Sends a reference indicating where the value is
  stored in memory, allowing the called procedure
  to actually change the arguments original value
• Default method if not specified ByVal or ByRef

7

• Private Sub SelectColor (lngIncomingColor As
  Long)
• With dlgColor
• .Flags cdlCCRGBInit Initialize the color
  dialog box
• .Color lngIncomingColor Set the initial
  color
• .ShowColor
• End With
• End Sub
• --------------------------------------------------
  ----------------------------------
• Private Sub cmdChangeMessage_Click()
• Dim lngOriginalColor As Long
• lngOriginalColor lblMessage.ForeColor
• SelectColor lngOriginalColor
• lblMessage.ForeColor dlgColor.Color
• End Sub

8

• Private Sub SelectColor (ByVal lngIncomingColor
  As Long)
• With dlgColor
• .Flags cdlCCRGBInit Initialize the color
  dialog box
• .Color lngIncomingColor Set the initial
  color
• .ShowColor
• End With
• End Sub
• --------------------------------------------------
  ----------------------------------
• Private Sub cmdChangeMessage_Click()
• Dim lngOriginalColor As Long
• lngOriginalColor lblMessage.ForeColor
• SelectColor lngOriginalColor
• lblMessage.ForeColor dlgColor.Color
• End Sub

9
Function Procedures versus Sub Procedures

• Sub Procedure is a procedure that performs
  actions and it also can return multiple values
• Function procedure may perform an action, but it
  also returns a value (the return value) to the
  point from which it was called

10

• Private Function curCommission (ByVal
  curSalesAmount As Currency) As Currency
• If curSalesAmount lt 1000 Then
• curCommission 0
• ElseIf curSalesAmount lt 2000 Then
• curCommission 0.15 curSalesAmount
• Else
• curCommission 0.2 curSalesAmount
• End If
• End Function
• --------------------------------------------------
  -----------------------
• Private Sub cmdCommission_Click ()
• Dim curSales As Currency
• If IsNumeric (txtSales.Text) Then
• curSales Val(txtSales.Text)
• lblCommission.Caption curCommission(curSales)
• End If
• End Sub

11

• Writing a Function with Multiple Arguments
• Private Function curPayment(curRate As Currency,
  _
• curTime As Currency, curAmt As Currency) As
  Currency
• curPayment curAmt (1 curRate / 12)
  (curTime 12)
• End Function
• --------------------------------------------------
  --------------------------
• Calling a Function with Multiple Arguments
• Private Sub cmdPayment_Click ()
• Dim curRate As Currency
• Dim curTime As Currency
• Dim curAmount As Currency
• curRate Val(txtRate.Text)
• curTime Val(txtTime.Text)
• curAmount Val(txtAmount.Text)
• lblPayment.Caption curPayment (curRate,
  curTime, curAmount)
• End Sub

12

• Reusing Procedures
• Private Sub mnuCalculateBonus_Click()
• Const curBonusPercent As Currency 0.01
• If curPurchase gt 0 Then
• curBonus curCalculateBonus (curPurchase,
  curBonusPercent)
• End If
• ----------------------------------------
• Private Sub mnuCalculateCommission_Click ()
• Const curCommissionLimit As Currency 500
• Const curCommissionPercent As Currency 0.05
• If curPurchase gt curCommissionLimit Then
• curCommission curCalculateBonus (curPurchase,
  _
• curCommissionPercent)
• End If
• ------------------------------------------
• Private Function curCalculateBonus (curAmount As
  Currency, curRate As _ Currency) As Currency
• curCalculateBonus curAmount curRate
• End Function

13

• Breaking Calculations into Smaller Units
• Private Sub mnyFileCalc_Click()
• curAverage curFindAverage (intGame1, intGame2,
  intGame3)
• intSeries intFindSeries(intGame1, intGame2,
  intGame3)
• curHandicap curFindHandicap (intGame1,
  intGame2, intGame3)
• strHighGame strFindHighGame (intGame1,
  intGame2, intGame3)
• ---------------------------------------------
• Public Function curFindAverage(intScore1 As
  Integer, intScore2 As Integer, _ intScore3 As
  Integer) As Currency
• curFindAverage (intScore1 intScore2
  intScore3)/3
• -----------------------------------
• Private Function curFindHandicap (curAverage As
  Currency) As Currency
• curFindHandicap (200 curAverage) 0.8
• ------------------------------------
• Private Function intFindSeries(intGame1 As
  Integer, _
• intGame2 As Integer, intGame3 As Integer) As
  Integer
• intFindSeries intGame1 intGame2 intGame3

14

• Private Function strFindHighGame(intGame1 As
  Integer, _
• intGame2 As Integer, intGame3 As Integer) As
  Integer
• If (intGame1 gt intGame2) Then
• If (intGame1 gt intGame3) Then
• strFindHighGame 1
• Else
• strFindHighGame 3
• End If
• ElseIf (intGame2 gt intGame3) Then
• strFindHighGame 2
• Else
• strFindHighGame 3
• End If
• End Function