Objects and Basic Programming Concepts (See Chapters 5 (skip ED 3), 6 of Albright) (See Chapters 5 (skip ED 4), 6 of Albright)

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1 Objects and Basic Programming Concepts (See Chapters 5 (skip ED 3), 6 of Albright) (See Chapters 5 (skip ED 4), 6 of Albright) Kipp Martin January 12, 2012

2 Excel Files Files used in this lecture: vbintroclean.xlsm rangeobject.xlsm variables.xlsm

3 Outline 3 Brief Review Simple I/O Variables: Part I Range Object Math Functions A Digression: With Blocks Important Pages

4 Brief Review 4 A class is characterized by its members. There are three types of members. methods or functions properties or data members events An object is a specific instance of a class. For example, Dim ws As Worksheet Set ws = Worksheets("DemoObject")

5 Brief Review Dot notation: We access members of an object by using dot notation. ws.range("a1").font.size = 22 What is ws? What is Range( A1 )? What is Font? What is Size?

6 Brief Review Sub SortStops() Range("A3:D15").Select Selection.AutoFilter Selection.Sort Key1:=Range("B4"), Order1:=xlAscending, _ Header:=xlGuess, OrderCustom:=1, _ MatchCase:=False, Orientation:=xlTopToBottom Range("A1").Select End Sub What are the member methods above? What are the method arguments

7 Brief Review 1. Make use of the Object Browser 2. Make use of Intellisense (or the Dummy Reminder as a former student once said)

8 Simple I/O In VBA it is often useful to output values of the variables. There are two easy ways to do this. Method 1: Use the MsgBox Method 2: Use Debug.Print Dim temp1 As Integer, temp2 As Integer temp1 = 5 temp2 = 7 MsgBox temp1 MsgBox temp2 MsgBox temp1 + temp2 MsgBox "Hello World" Debug.Print temp2

9 Simple I/O Debug.Print prints to the Immediate Window. To open the Immediate Window, in the VBA Editor go to the View menu item. Select Immediate Window

10 Simple I/O It is also easy to get data into the VBA program. Use InputBox. Two arguments. Argument One: message to user Argument Two: Title of InputBox Dim stockprice As Double stockprice = InputBox("Enter the Stock Price", _ "Stock Price") Debug.Print stockprice

11 11 Variables and DataTypes In VBA you will work with variables that are defined to be a Data Types. The ones we will work with most frequently are: Integer (-32,768 and 32,767) Long (2,147,483,648 to 2,147,483,647) Double Date Currency String Boolean Range Worksheet Object Variant

12 Variables and DataTypes Statically Typed Language: variables are fixed at compile time. With a statically typed language must declare variable type before using it. Examples include Java and C/C++. Dynamically Typed Language: types are discovered at run time based on how they are used. Scripting languages such as Python and VBA are dynamically typed. Critical: Make VBA statically typed using Option Explicit

13 Variables and DataTypes Strongly Typed Language: Data types are always enforced. The following is not allowed in strongly typed language such as Java or Python, but is allowed in VBA. Dim type1 As String type1 = "12" Dim type2 As Integer type2 = 3 MsgBox type1 / type2 Weakly Typed Language: Types are combined and the compiler tries to make sense of what you are doing. VBA and C/C++ are weakly typed (actually C/C++ not nearly as weakly typed as VBA). Not all scripting languages are weakly typed (e.g. Python is not).

14 Variables and DataTypes In VBA a variable is explicitly declared using the Dim and As keywords. The syntax is Dim variable As DataType Important: In VBA variable names are case sensitive. The Dim statement is explicitly declaring a variable. You can also do it implicitly. i = 5 Don t do this!!!!!!!!! Don t do this!!!!!!!!! Start your modules with Option Explicit Tools > Options Check "Require Variable Definition"

15 Variations on a theme Dim i As Integer Dim j As Integer Dim k As Integer OR Variables and DataTypes Dim i As Integer, j As Integer, k As Integer ALSO POSSIBLE Dim i As Integer, s As String, x As Double NOT Dim i, j, k As Integer In this case i and j end up as Variant not integer which is bad.

16 Integers, Doubles, Currency, and Date Variables that are numbers will usually be integers, doubles, currency, or date Data Types. Dim age As Integer Dim x As Double Dim birthday As Date Dim money as Currency age = 33 x = 32.7 birthday = #1/3/75# age = Year( Now()) - Year(birthday) MsgBox "Age = " & age money = VBA.Format( , "Currency") MsgBox "Salary = $" & money

17 String Variables Dim firstname As String Dim lastname As String Dim midinitial As String * 1 Dim fullname As String firstname = "John" lastname = "Doe" midinitial = "Q" fullname = firstname & midinitial & lastname MsgBox fullname Note how strings are defined using the Note how strings are added (concatenated)

18 Converting String Variables You can t manipulate string data as numbers. For example, do not: Dim myvar1 As String Dim myvar2 As String Dim myvar3 As Double myvar1 = "32.46" myvar2 = "77.9" myvar3 = myvar1 + myvar2 MsgBox myvar3 Instead use the string conversion functions CDbl and CInt to convert text to numbers. Use CStr to convert numbers to strings.

19 Converting String Variables Sub StringOps() Dim myvar1 As String Dim myvar2 As String Dim myvar3 As String myvar1 = "32.46" myvar2 = "77.9" myvar3 = myvar1 + myvar2 MsgBox myvar3 Dim dval1 As Double, _ dval2 As Double, dval3 As Double dval1 = CDbl(myVar1) dval2 = CDbl(myVar2) dval3 = dval1 + dval2 MsgBox dval3 End Sub

20 String Variables 20 Some neat string functions: The string length function Dim myvar1 As String myvar1 = "Bus 36104" MsgBox Len(myVar1) What is the result?

21 String Variables Some neat string functions: getting segments of a string Dim rightstring, midstring, leftstring As String Dim teststring As String teststring = "Applications Development with VBA" rightstring = Right(testString, 5) midstring = Mid(testString, 2, 7) leftstring = Left(testString, 7) MsgBox rightstring MsgBox midstring MsgBox leftstring What is the result?

22 String Variables The string functions built into VBA are actually rather limited. For example, you might like to search a string to see if it contains text of interest. You can take advantage of built-in Excel functions for this. More later.

23 Boolean Variables Boolean variables take on values of True or False. Boolean variables are used in logical tests (If, While, etc.). Dim test As Boolean test = True

24 Values for Data Types Here are some ranges on common data types. Integer: stored in two bytes can take values -32,768 to 32,767 Double: stored in eight bytes and can take values in the range E308 to E-324 for negative values; E-324 to E308 for positive values Date: stored in eight bytes and takes a value from January 1, 100 to December 31, 9999 Currency: stored in eight bytes and takes a value with a range of -922,337,203,685, to 922,337,203,685, String: variable length, can go up to approximately 2 billion characters Boolean: two bytes True or False

25 Range Variables We can declare Range variables. This variable will have access to all of the properties and methods of the Range class. Dim rng As Range Set rng = Range("A1") Note the use of Set. You need to use the Set keyword when defining a range object.

26 Range Variables: StartCell, EndCell When writing code we may to treat the start and end of a range as a variable. Rather than copying exact cell names we can point to start or end cells. Dim StartCell As Range Dim EndCell As Range rangestart = InputBox("Enter Start Cell") Set StartCell = Range(rangeStart) rangeend = InputBox("Enter End Cell") Set EndCell = Range(rangeEnd) Set rng = Range(StartCell, EndCell) rng.select MsgBox "The range is: " & rng.address

27 Worksheet Variables Dim ws As Worksheet Set ws = Worksheets("Sheet1") We use the Set keyword again when working with the Worksheet class We use Worksheets( Sheet1 ) NOT Worksheet( Sheet1 )

28 Object Variables You can declare a generic object variable. This can be a Range, Worksheet, Drawing Object, whatever. Dim myobj As Object Set myobj = rng Set myobj = ws ws.shapes.addshape(msoshaperectangle, , 289.5, _ 50, 100).Select

29 Constant Variables By definition variables are just that variable, they can change as the procedure changes. Dim myint As Integer myint = 57 Do some work Do some more work myint = 59 However, there is a such a thing as a constant variable. This is variable that cannot change during execution. Const MY_PIE = 3.14 Const MY_INFINITY It is common to use all upper case for constant variables although this is not necessary.

30 Range Object The range object is probably the most important object you will work with. In VBA it is critical to be able to refer to ranges, and parts of ranges, in your code. Method 1: Cell Address Dim rng As Range Set rng = Range("A1:G12") Method 2: Range Name Dim rng As Range Set rng = Range("tax_rates")

31 Range Object Method 3: Cells Property This uses the standard (i, j) matrix notation. Range("A1:A100").Cells(7) refers to cell $A$7 Note: you can always check to see cells the range refers to. Dim rng As Range Set rng = Range("A1:A100").Cells( 7) MsgBox "The Range address is: " & rng.address

32 Range Object (Cell Property Continued) Method 3: Cells Property This uses the standard (i, j) matrix notation. Range("A1:D100").Cells(3, 2) refers to cell $B$3 Range("E3:G100").Cells(3, 2) refers to cell $F$5

33 Range Object Method 4: Offset Property This takes two arguments, but the origin of the range is (0,0) in the upper left and we offset the start and end by the amount of the offset. Range("A1:D3").Offset(0, 0) refers to cell $A$1:$D$3 Range("A1:D3").Offset(1, 1) refers to cell $B$2:$E$4 Contrast with Range("A1:D3").Cells(1, 1) refers to cell $A$1 Range("A1:D3").Offset(3, 2) refers to cell $C$4:$F$6 Range("E3:G100").Offset(3, 2) refers to cell $G$6:$I$103 Range("A1").Offset(3, 2) refers to cell $C$4

34 Range Object Method 5: Upper Left, Bottom Right You can define a range by specifying the upper left cell and bottom right cell. Range("A1", "B2") refers to Range $A$1:$B$2 Range( Range("A1"), Range( B2 ) ) refers to Range $A$1:$B$2 Range( Range("A1").Offset(1, 1), Range("A1").Offset(3, 4) ) refers to Range $B$2:$E$4 You will see in an exercise how this is very useful.

35 End Property Method 6: Using the End Property This is very useful when you don t know the size of a rage ahead of time. Range("G1", Range("G1").End(xlToRight)).Name = "Quizzes" Range("G1", Range("G1").End(xlToRight)).Select There is also an xldown

36 Counting Range Size It is often useful to know how many rows and columns are in a range. Dim rng As Range Set rng = Range("A3:D50") MsgBox "Num rows = " & rng.rows.count MsgBox "Num cols = " & rng.columns.count

37 Writing to the Worksheet There are a lot of ways to enter text or formulas into a cell. Sub WriteToRange() Dim ws As Worksheet Set ws = Worksheets("writeRange") Dim rng As Range Set rng = Range("A1:A3") Range("A1").Formula = "=B1" rng.cells(2, 1) = "=B2" Range("A3") = "=B3" Range("A4").FormulaR1C1 = "=RC[1]" End Sub

38 Math Functions Key Idea: There are a number of math functions in VBA that you can use without using any cell references. 38

39 Functions Using Excel built-in functions: Dim x, y As Double x = 100 y = Sqr(100) MsgBox "y = " & y x = Exp(1) y = Log(x) MsgBox "y = " & y

40 Math Functions You can also use the wide variety of Excel built-in functions (really useful when you are working with the range object). Dim x, y As Double x = Application.WorksheetFunction.Sum(Range("numbersRange")) y = Application.WorksheetFunction.Log10(10) MsgBox x MsgBox y

41 Math Functions 41 Another Approach: Dim ws As Worksheet Set ws = Worksheets("Sheet3") Range("A1").Value = "=Log10(10)" ws.range("a11").value = "=Sum(numbersRange)"

42 Math Functions Using a String Function: Dim pos As Integer Dim mystring As String mystring = "Goodbye Cruel World" pos = _ Application.WorksheetFunction.Find("Cruel", mystring, 1) Debug.Print pos

43 With Block When setting numerous properties for a Range object you can save effort by using a With block. The general structure is: With ObjectName.property.method End With Range("A1").Value = Range("A1").Name = "SalesPrice" Range("A1").Font.Size = 12 Range("A1").Font.Italics = True Range("A1").Font.Name= "Time New Roman"

44 With Block Range("A1").Value = Range("A1").Name = "SalesPrice" Range("A1").Font.Size = 12 Range("A1").Font.Italics = True Range("A1").Font.Name= "Time New Roman" With Range("A1").Value = Name = "SalesPrice" With.Font.Size = 12.Italic = True.Name= "Time New Roman" End With End With

45 Important Pages Highly Recommended: pages (Third Edition) pages (Third Edition) pages (Fourth Edition) pages (Fourth Edition)

46 Summary Tips Use the object browser Use the idiot completion Make use of the Range Address property Make use of the Range Count property Use an underscore to continue a line Use a single quote for a comment

Excel VBA Variables, Data Types & Constant

Excel VBA Variables, Data Types & Constant Variables are used in almost all computer program and VBA is no different. It's a good practice to declare a variable at the beginning of the procedure. It is