Visual Basic Objects / Properties / Methods PropertyAdjective ObjectNoun Part of the application Attribute MethodVerb Action to do something

Visual Basic Range (“A3”).select Range is an object select is a method (“A3”) is a modifier for the object Note that object separated from method by a.

Activesheet.name Activesheet is an object name is a property Visual Basic The result is the name of the active sheet

Procedures Sub procedures return no values except by changes to parameters in the argument list Function procedures return a value by assigning it to the name of the function.

Function Procedures Function Grade (exam1,exam2,exam3) as String Sum = exam1+exam2+exam3 If Sum > 95 then Grade = “A” Elseif Sum > 80 Grade = “B” Else Grade = “C” Endif End Function Dim Sum as Single

For functions and sub procedures, there is a one to one correspondence between the arguments in the call to the function and the argument list of the function: Function Grade (exam1,exam2,exam3) as String The call: = Grade( 90, C40, $C$60 ) The definition:

Sub Procedures Public Sub ColorList() ' Lists all the available colors in the current pallette ' Number is listed in column 2, color sample in column 3 ' List starts in row 5 Dim I As Integer Dim J As Integer Dim K As Integer J = 5 I = 2 For K = 1 To 56 Cells(J, I).Value = K Cells(J, I + 1).Interior.ColorIndex = K J = J + 1 Next K End Sub Note that ColorList is never assigned a value!

Review of some Excel Basics Cell references of two types: A1 Columns are alphabetic, rows are numeric R1C1 R number Column number B2 and R2C2 refer to the same cell Can be set by the Tools / Options menus (Note that the two methods are transposed – A1 – column first, then row R1C1 – row first, then column )

Formulae in Excel (R1C1 style) R1C1 is an absolute address – it does not change under copy / paste R[1]C[1] is a relative address – it does change under copy /paste And can use mixed mode: R1C[1] – R1 is absolute, C[1] is relative

In VBA, can use either or both A1 and R1C1 styles A1 style tends to be absolute A1 style used with the “Range” object Range(“A4”) Can refer to individual cells with the “Cells” object, which uses an R1C1 style Cells(4,1)

In Excel, cells & ranges can be named Insert / name menu These names can be used in Formulae VBA

VBA Variable Types String A sequence of bytes containing characters Integer 2 byte integer Long 4 byte integer Single 4 byte real number Double 8 byte real number VariantCan hold anything (but “expensive” to use) “Object”A class of data types used by Excel/VBA

Characters & Stings For Excel, anything that is not a number or a formula is a string. If want a set of digits as a string, need to enclose in quote or quotation marks. For VBA, need to define variable that will hold strings as string data types

Visual Basic Sub NameIt() Dim newname as String newname = InputBox(“Enter a name for the worksheet”) ActiveSheet.Name=newname End Sub Example -- simple Sub to name the active worksheet:

“Object” data type Many of the objects in Excel have their own data type: Dim r as Range Dim q as Worksheet Dim z as Chart About the only one we will use is the “Range” data type.

Option Explicit Forces you to ‘Dim’ all variables Helps prevent typos Can set this as the default through the Tools/ Options menu. (Require variable declaration check box)

Visual Basic All objects have properties Most objects have methods Will work with only a few of the many objects, methods and properties To get a list of objects and properties, invoke the Object Browser (F2)

Program module (Sub or Function) is made up of a series of steps to accomplish a task. Five major categories of steps: Assignment statements A = 5 Conditional statementsIf ( A > 5) then …. Calls to other modulesA = sqrt (12) Input /Output operations (Which are really calls to other modules) Read 5, A Iteration Statements For I = 1 to 6 … Next i

Expression evaluation inVBA Operators in priority order Left to right Operator Priority List ( ) ^ - (unary minus) * / + - Comparison Operators (>, < …) Logical Operators (NOT, AND, OR…)

Test = ^2 > 5 AND (3-7)*2 > 6 (3-7)-4 3^2 9 -4* > 5True -8 > 6False True AND FalseFalse Thus, Test has the value “False”

Conditional Expressions If / then / else end if Select case …. End Case

If (expression) then One or more expressions Else One or more expressions End If If (expression ) then (expression) Note: no End If statement for this type of If /then expression

Select Case testexpression [Case expressionlist-n [statements-n]]... [Case Else [elsestatements] ] End Select Select Case Statement Like a complex If / Then / ElseIf … / EndIf

Select Case Statement Testexpression can be any that evaluates to a numeric value or a string Expressionlist is compared to the testexpression to determine if the following statements should be executed. See “Help” for all the allowable forms Statements are executed up to the next Case statement or the End Select statement

A simple example Case statements to determine a letter grade from a numeric grade. Assume the numeric grade is in the variable “grade”

Select Case grade Case Is >=90 ltrgrade=“A” Case Is >= 85 ltrgrade = “BA” … Case Is >= 70 ltrgrade = “C” Case Else ltrgrade=“E” End Select Note: Goes to first Case that testexpression satisfies. Is implicitly uses grade in the comparison

Generally speaking, anything you can do with a Select Case block, you can do with a set of If / Then / Else If … / End If statements

Iteration Statements Used to execute a number of statements repeatedly Two major types --- For / Next Do / Loop

For counter to upperlimt step size Statements Next counter For Each cell In Selection Statements cell.value= expression Next cell

Do statements Loop Basic “ Do Loop” Structure But we need a mechanism to stop the loop!

Do while expression_is_true Statements Loop Do Statements Loop while expression_is_true

Do Until expression_is_true Statements Loop Do Statements Loop Until expression_is_true

Do...Loop Statement Example This example shows how Do...Loop statements can be used. The inner Do...Loop statement loops 10 times, sets the value of the flag to False, and exits prematurely using the Exit Do statement The outer loop exits immediately upon checking the value of the flag. Dim Check, Counter Check = True Counter = 0 ' Initialize variables. Do ' Outer loop. Do While Counter < 20 ' Inner loop. Counter = Counter + 1 ' Increment Counter. If Counter = 10 Then ' If condition is True. Check = False ' Set value of flag to False. Exit Do ' Exit inner loop. End If Loop Loop Until Check = False ' Exit outer loop immediately

To manipulate a cell’s value, use the “value” property of the cell object: Range(“A4”).value = 20 Temp = Range(“A4”).value or Cells(4,5).value = 20 Temp = Cells(4,5).value

Build a simple module to set a 5 x 5 array of cells to some value In VBA IDE Insert module Insert procedure / sub Initcells Dim I as integer Dim J as integer For I = 1 to 5 For J = 1 to 5 Cells(I,J) = I*J Next J Next I Return to Excel and run macro Initcells

Two useful VBA functions to interact with use: Str1 = InputBox(“prompt’) When invoked, displays the prompt and gives you a box to enter a reply, which is placed in Str1 Dim str1 as String str1 = InputBox(“Please enter your name”) InputBox displays a prompt and awaits a reply

MsgBox displays a message and buttons to press. The function value returned is the code for the button J = MsgBox(“prompt”,buttoncodes, “ box name”) Look at ‘Help” for the button code values J is the integer value of the button code the user presses Code=MsgBox(“Are you OK”,vbOKOnly,”My Temp”)

Write a simple sub (called Heater) that accepts a temperature as an argument and returns a string to indicate what to do with the heater. Also have MsgBox display a message to the use if the heater status is changed. The logic for the heater control is as follows: If the temperature is less than 65, “Turn heater on” If the temperature is greater than75, “Turn heater off” Otherwise, “Leave heater alone” Function Heater (Temp) As string Code End function