Controlling Execution

IF and only if..

• One line IF

• IF with and without ENDIF

• IF with and without ELSE

• One line ELSEIF

• Multiple ELSEIFs and Select Case

IF and only if..

• One line IF (without END IF) IF (condition) Then Exit Sub• One seeming line IF IF (condition) Then _ Exit Sub• IF with ENDIF IF (condition) Then Exit Sub END IF

IF and only if..• One line IF with ELSE IF (whatever) Then Yada ELSE YadaYada

• Five line IF with ELSE IF (whatever) Then Yada ELSE YadaYada END IF

IF and only if..

• ELSE required alone on one line IF (whatever) Then

Yada

ELSE

YadaYada

END IF

• THEN at end of line required

• END IF required alone on one line

ElseIF and only if..

• ElseIF is subordinate to the previous IF

IF (whatever) Then

Yada

ElseIF (whatever) Then

YadaYada

ELSE

YadaYadaYada

END IF

Select Case vs ElseIF

• Select Case neat and maintainable

• Case formats very flexible

• Case 1,3,7

• Case 2 to 8

• Case “CA” to “NM”

• Case Is > 21

Select Case Example

Select Case SecurityCase "V"

' set properties for volunteers

Case "S"

' set properties for supervisors

Case ""

' exit sub

End Select

Immediate If!

• IIF is a function

• IIF(condition, true return, false return)

• IIF(blnMale=True,”Male”,”Female”)

• Useful in queries, properties, division

• IIF(intN > 0, 300/intN, 0) ' to avoid an error msg

• IIF(PercentCorrect>=90,"A", _

• IIf(PercentCorrect>=80,"B", _

• IIf(PercentCorrect>=70,"C", _

• IIf(PercentCorrect>=60,"D","F"))))

For Loops

• For intX = 1 to 10 Step 2 • For Each varX in varDataSet

– Next required for these two For formats

• Exit For

Restrictions on For Each…• 1-dimension only• Each control variable must be Variant

For Loops: Examples

Dim varDataSet(0 to 49) as VariantDim intX as Integer, intOdd as IntegerDim intSum as IntegerDim varItem as Variant, varSum as Variant' sum the odd numbered elements (1,3,5,…)For intX = 1 to 49 Step 2

intOdd = intOdd + varData(intX)Next' sum all elements (1,2,3,…) For Each varItem in varDataSet intSum = intSum + varItemNext

Do Loops

Conditional logic after 1 pass through loop• Do … Loop While• Do … Loop Until

Or, conditional logic before 1st pass through loop• Do While … Loop• Do Until … Loop

Exit Do

Arrays

• Lists (states, income levels, schedules, etc)

• Private, Public, fixed or dynamic size

• Dim ccyIncomeLevel(0 to 5) As Currency

Which Array to Go?

• Option Base 1 or Option Base 0?

• Public strState(0 to 49) As String

• Public strState(1 to 50) As String

• Public strState(50) As String– Above will be (0 to 49 or 1 to 50)

depending on Option Base

strMonth(1) = "January"

strMonth(2) = "February"

strMonth(3) = "March"

strMonth(4) = "April"

strMonth(5) = "May"

intInput = InputBox("Enter Month Number")

MsgBox “You mean “& strMonth(intInput) & “?”

Or MsgBox “You mean “& strMonth(intInput+1) & “?”

Flexible Array

• Dynamic• Dim ccyLevel() As Currency

• Expands and contracts

• Good for uncertain run-time conditions

• Can loose contents unless…– Redim Preserve ccyLevel(7)

• Can erase dynamic arrays: Erase ccyLevel

Strings

Notes on strings

• String variables (Dim strName as String)• String literals (txtName = "Jones")

• Mixing variables and literalsSelect * from tblRoster Where Name = "Smith"

• How to embed quotes around strName?"Select * from tblRoster Where Name =" & ???

' If the name is a hard-coded literalDebug.Print "Name = 'Smith'"

' If the name is in a variable (very likely)Dim strName As StringstrName = "Smith"

Debug.Print "Name = '" & strName & "'"

How to embed single quotes

' When the name is a hard-coded literalDebug.Print "LastName = ""Smith"""

'Coding hints for the triple quotes above: 'step 1: LastName = "Smith" 'step 2: LastName = ""Smith"" 'step 3: "LastName = ""Smith"" "

How to embed double quoteswith literal strings

Dim strName As StringstrName = "Smith"Debug.Print "LastName = """ & strName & """" 'Coding hints for triple/quadruple quotes: 'step 1: "LastName = strName" 'step 2: "LastName = """ & strName " 'step 3: "LastName = """ & strName & """ "

How to embed double quotesusing variables

Dim strName As StringstrName = "Nguyen"

Dim strQuote As StringstrQuote = Chr(34) ' ACSII for double quote

strName = strQuote & strName & strQuoteDebug.Print "LastName = " & strName

How to embed double quotesas a variable

String Functions

• mid(strHayStack, intStart, intLength)– Returns string or part of a string

• instr(intStart, strHayStack, strNeedle)– Returns position where needle is in haystack

Mid()

MyString = "Mid Function Demo" ' Create text string.

FirstWord = Mid(MyString, 1, 3) ' Returns "Mid".

LastWord = Mid(MyString, 14, 4) ' Returns "Demo".

MidWords = Mid(MyString, 5) ' Returns "Function Demo".

InStr()

strHaystack ="XXpXXpXXPXXP“strNeedle = "p"

intWhere = Instr(1, strHaystack , "W") Returns 0

intWhere = Instr(4, strHaystack , strNeedle )

Returns 6

Other String Functions

• Left() and Right() ' args: string, no. of chars

• Ucase() and Lcase() ' one arg only

• Trim(), Rtrim() and Ltrim() ' one arg only

• Val(strA) ' change a string to a number

• Cstr(intX) ' change a number to a string

• Because Cstr(57) returns " 57" not "57" use Trim(Cstr(intX))