Week 2

 Macros revisited  The VBA Editor  The object model  Using variables  If statements

 Record a macro that formats highlighted cells to appear as integers (enter some decimal numbers to test it on)  Create a Message Box that looks like this:  (tip the icon is called vbInformation)

 Your macro might look something like this: Sub Macro2() ' ' Macro2 Macro ' Selection.NumberFormat = "0.00" Selection.NumberFormat = "0.0" Selection.NumberFormat = "0" End Sub

 Your macro should look something like this: Sub IntegerFormat() ' Format highlighted cells as integer Selection.NumberFormat = "0.00" Selection.NumberFormat = "0.0" Selection.NumberFormat = "0" End Sub

 Your macro should look something like this: Sub IntegerFormat() ' Format highlighted cells as integer With Selection.NumberFormat = “0“ End With End Sub

 Formatting Fonts  Record a new macro to format the selected cells as follows: Tahoma, Bold, Size 14  Edit your macro using With Selection.Font ensuring that there is no unnecessary code (don’t forget to End With)

 User friendly environment for writing VBA code  Access the VBE by pressing Alt-F11  The programming workspace includes: The Code window The Project Explorer  Worksheets + Chart Sheets  ThisWorkbook  Modules (for VBA code)  User forms (for dialog boxes) The Properties Window

Project explorer Properties window Code window Immediate window

1. Provide sufficient comments Start the line with a single quote The line is coloured green and ignored by VBA 2. Indent consistently Provide a logical structure to your program 3. Use white space liberally  Use Names wisely – “Macro1” is fine now, but less helpful for future reference 10

 Objects Car, Engine, Spark plugs, Door(s)  Properties (Values) Colour (red), Type (1.4l), Age (4 years), size (4- door), Locked (True)  Methods (arguments) Do Locking (central), Turn over, Spark, Drive (10mph), Reverse  Events Hit wall, Reach speed limit, Driver turns key

 Examples of Objects: Ranges, worksheets, charts, workbooks  Each object has properties, i.e. the attributes of the object e.g., a cell has a Value property (either text or number in the cell), a Formula property (the formula in the cell) and a HorizontalAlignment property (left, center or right).

The Object Model  Each object has methods, i.e. the things you can do to an object e.g., a cell has the ClearContents method to erase the content of the cell (equivalent to the delete key).  Some methods have arguments, i.e. qualifiers indicating how a method is performed e.g., the Copy method has a Destination argument.

 Objects can be manipulated using the collections they belong to, specifying their location in the object hierarchy using the dot notation. Worksheets(“Sheet1”) Worksheets(1) Workbooks(“Book1”).Worksheets(“Sheet1”) Worksheets(“Sheet1”).Range(“A1”) Application.Workbooks(“Book1”)._ Worksheets(“Sheet1”).Range(“A1”)

 Online help tool.  Click on the Object Browser button in the Standard toolbar.  Select Excel Libraries List of all objects (on the left) List of properties and methods for each object (on the right)  Properties: hand icon  Methods: green rectangular icon  To get help on any item, select it and click on the question mark button.

Variables Variable: A variable is a mechanism which enables you to store information and use it while a program is running. As the name implies, it is possible to change the value during the running of a program

Variables Option explicit Sub hello() Dim username As String username = InputBox("Please enter your name") MsgBox "Hello " & username End Sub

Variable names  Valid variable names can contain text or numbers but they must use a letter as the first character.  You can't use a space, period (.), exclamation mark (!), or the /, &, $, # in the name.  Names cannot exceed 255 characters in length (short and to the point is best)  Be descriptive

Variable types  Byte  Integer  Long  Single  Double  Currency  Boolean  Date  String  Object  Variant 0 to to bn to 2.1 bl Regular decimal numbers Large decimal numbers trn to 9.22 True / False 1/1/100 to 31/12/9999 “2bn characters” Any object reference Avoid

Variable names and types  Suggest suitable variable names and types for variables representing: GDP of a country Client name Client reference number Price of an item of stock Number of items in stock Number of staff in a department Agent’s commission rate Invoice due date Invoice state (paid or unpaid)

Exercises  Open week3.xls  Open the VBE and look at the Macro Orders Why won't it run? Can you fix the errors?

Declaring and assigning variables  Variables are declared to exist within a program  A variable can be initialised with a value  A variable can have different value while a program runs  Dim xxxx As type Dim stands for dimension As assigns type Dim x, y, z as integer (wrong) Dim x as integer, y as integer, z as integer (correct)

Option Explicit Sub Example() Dim x As Byte x = InputBox (“Enter a number between 1 and 10”) MsgBox x End Sub  Use Option Explicit at the head of a module to force variable declaration  You can automatically use Option Explicit Tools>Options>Require variable declaration

Assigning variables  Variable on the LHS, Value on the RHS  x = 1 the value 1 is assigned to x  SalesRegion = “North West” use double quotes when assigning string variables   NextFinYear = #1-April-2009# Use # to enclose the value of a date, NB date format defaults to US (very inconvenient!)

Assigning variables  DeliveryDate = OrderDate + 3  y = x a variable y is assigned the value of x  OrderTotal = Subtotal * VatRate  OrderNo = OrderNo + 1 increases the value of a variable called OrderNo by 1 (called incrementing)  y = Range(“B3”).Value

Arithmetical Operators OperatorOperationExampleAnswer + Add Subtract7-25 * Multiply3*515 / Divide10/42.5 \ N1 \ N2 - integer division15\43 Mod X Mod Y returns remainder10 mod 31 ^ X ^ Y gives the value of X raised to the power of Y 2^38

Calculations with variables Sub example1() 'declare variables Dim x as integer, y as integer, z as integer ' assign values to variables x = 3 y = 4 z = x + y ' output result Msgbox z End sub

Using variables sub enterNumbers () Dim Number as Integer number = InputBox("Enter number under 5000", "Enter_ numeric data") number = number * 2 MsgBox "The number multiplied by 2 is " & number, _,,"Greeting Box" End Sub

Concatenation  Concatenation operator & is used to join things together e.g. a number to text. For example: MsgBox "You will be paid " & payrate & " per hour" “&” concatenates string and numeric variables, so you should use it if you want to combine a string and a number  There is also + but this can only concatenate one string to another; if you use it to concatenate a number to text you will get a run-time error

Exercises  Introductory  Reading cells

Constants  Used for a value that recurs but never changes throughout the programme  Const taxRate = 0.28  Can now refer to taxRate during the programme and can easily update the value by changing this one line of code

Built-in Constants  Prefix vb or xl in the Object library ColorConstants Excel Direction

If statements If condition Then doSomething Elseif anotherCondition Then doSomethingElse ElseIf anotherCondition Then doSomethingElse Else doSomethingElse End If =equal to <less than <=less than or equal to >greater than >=greater than or equal to <>not equal to

If statements – an example Sub Profit_Loss () Dim profit As single profit = Range("C1").Value If profit > 0 Then MsgBox "You have made a profit" ElseIf profit = 0 Then MsgBox "You have broken even" Else MsgBox "you have made a loss" End If End Sub

If statements – an example Sub Profit_Loss () If Range("C1").Value > 0 Then MsgBox "You have made a profit" ElseIf Range("C1").Value = 0 Then MsgBox "You have broken even" Else MsgBox "you have made a loss" End If End Sub

Exercises  Pebbles and Muffins

Next week  Assessed Exercise Variables and if statements  Using Ranges in VBA