Ethics

CS 106Computing Fundamentals IIChapter 17“Introduction To VBA”

Herbert G. Mayer, PSU CSHerbert G. Mayer, PSU CS

status 6/30/2013status 6/30/2013

Initial content copied verbatim fromInitial content copied verbatim from

CS 106 material developed byCS 106 material developed by

CS professors: Cynthia Brown & Robert MartinCS professors: Cynthia Brown & Robert Martin

Syllabus

Not An Introduction to ExcelNot An Introduction to Excel

Idea of ObjectsIdea of Objects

EventsEvents

But First: A WarningBut First: A Warning

Security SettingsSecurity Settings

Macro RecordingMacro Recording

Look at CodeLook at Code

What is Code?What is Code?

Not An Introduction to Excel

•Assumption: you have a basic familiarity with Excel•Assumption: you have a basic familiarity with Excel

•If you don’t, or you need a review, you can get startedby going through the Introduction to Excel in the firstmodule•If you don’t, or you need a review, you can get startedby going through the Introduction to Excel in the firstmodule

Idea of Objects

•VBA is built on the idea that a workbook is ahierarchy of objects•VBA is built on the idea that a workbook is ahierarchy of objects

•An object can contain other objects; for example, aworkbook contains worksheets, and the worksheetscontain cells•An object can contain other objects; for example, aworkbook contains worksheets, and the worksheetscontain cells

•An object can have properties, like the value in a cellor the font used in a cell•An object can have properties, like the value in a cellor the font used in a cell

•An object can have methods, which are actions thataffect the object•An object can have methods, which are actions thataffect the object

Events

•Objects can have events: for example, opening aworkbook is an event; so is clicking on a cell•Objects can have events: for example, opening aworkbook is an event; so is clicking on a cell

•Our VBA programs perform tasks when eventshappen•Our VBA programs perform tasks when eventshappen

•The spreadsheet or Excel form we are working withwill serve as the user interface, and events likeclicking a button will trigger the performance of a task•The spreadsheet or Excel form we are working withwill serve as the user interface, and events likeclicking a button will trigger the performance of a task

Macros

•VBA programs are called macros. The simplest wayto get started writing macros is to record one. Thisfeature lets VBA produce code based on actions youperform while recording•VBA programs are called macros. The simplest wayto get started writing macros is to record one. Thisfeature lets VBA produce code based on actions youperform while recording

•We’ll go through an example•We’ll go through an example

•This is not a proper way to create macros other thanreally simple ones, especially if formulas are involved•This is not a proper way to create macros other thanreally simple ones, especially if formulas are involved

•It is good for getting an idea of what kind of code towrite to perform a particular task•It is good for getting an idea of what kind of code towrite to perform a particular task

BUT FIRST: A Warning!

•Macros can be dangerous! They can change files onyour computer, send emails to everyone in youraddress book, and insert spyware; hackers love them•Macros can be dangerous! They can change files onyour computer, send emails to everyone in youraddress book, and insert spyware; hackers love them

•Caveat: NEVER run macros from an un-trustedsource•Caveat: NEVER run macros from an un-trustedsource

•The default setting on the Macro Security control (inWindows) is a good one: you have to authorizemacros before you can run them•The default setting on the Macro Security control (inWindows) is a good one: you have to authorizemacros before you can run them

Here’s the control for the securitysettings (Windows version)

Macro Security control

Get to “Trust Center” Window byclicking the Macro Security control

This defaultsetting is thecorrect one forus

You will have to check a box toenable macros to run wheneveryou open a workbook withmacros in it.

You will also have to save yourworkbook as a “Macro-enabledWorkbook” with extension.xlsm

Macro Security (Mac version)

Get this window by clickingPreferences

under the Excel menu

Be sure that the “warn before opening a file

that contains macros” box is checked

Recording a Macro (Windows)

There are two macro recordingbuttons as shown by the arrows.You can push either one to beginrecording.

Relative References Control

The “Use Relative References”button lets you choose whether touse relative or absolute referenceswhen recording your macro.

The default is to use absolutereferences.

Macro Recording on the Mac

Macro recording button

Relative references control

Note these are on the Developer tab

Recording a simple macro

•This macro is in the workbook CopyCols.xlsm postedon the website•This macro is in the workbook CopyCols.xlsm postedon the website

•Using absolute references, we’ll copy one column toanother•Using absolute references, we’ll copy one column toanother

•The example is shown in Windows; doing it on theMac is quite similar•The example is shown in Windows; doing it on theMac is quite similar

The Worksheet Before WeRecord

I used R1C1 in Row 1Col 1 etc. so you cansee where data comesfrom when we copy it.

Here’s the screen we get when wepush the Record Macro Button

I gave it a

descriptive

name.

If you give it a shortcut key,

make sure it doesn’t conflict

with an important one

Be sure to

describe what

it does

Our usual

option

After you push OK, recording begins

You can see the Mac version has basically the same interface as the

Windows version

In the middle of recording…

Clickhere

whendone

[On the Mac, just click the record button again

to stop]

To run Macro Push Macro Button

Highlightthe macroyou wantto run andpush therun button

Add a Button to Run the Macro(Windows)

On the developertab, under Insert,click the littletriangle. The iconfor a button is at theupper left underForm Controls

Add Button to Run the Macro (Mac)

On the Mac, the controls you can add

are in the ribbon

Click to put Button onto Worksheet

•Put it about where you want it, but you can alwaysmove it later•Put it about where you want it, but you can alwaysmove it later

•The next step is to associate the button with themacro•The next step is to associate the button with themacro

•The screen on the next page will come upautomatically•The screen on the next page will come upautomatically

Highlight Macro Name, Click OK

Before

After

Click on the button to get a cursor totype meaningful text

Final Product

I had to make thebutton longer to holdthe text I wanted

Let’s Look at the Code!

Click the Macrosbutton at theupper left of thedeveloper tab andthen click the Editbutton. This willtake you to theVBA Editor.

The VBA Window (Windows)

Project

Window

Properties

Window

CodeWindow

Let’s just look at the codefor now

Code Explanation

Sub CopyAtoD()Sub CopyAtoD()

' CopyAtoD Macro' CopyAtoD Macro

' Copy Column A to Column D' Copy Column A to Column D

Columns("A:A").Select Columns("A:A").Select

Selection.Copy Selection.Copy

Columns("D:D").Select Columns("D:D").Select

ActiveSheet.Paste ActiveSheet.Paste

End SubEnd Sub

A “Sub” is a workingpiece of code, a Macro.This is the code for ourMacro CopyAtoD

A line that starts with a ‘ isa comment. It is not part ofthe code. VBA used ourdescription for thiscomment. The editorcolors comments green

The End Sub closes offthe code for thissubroutine. Sub and EndSub are key words forthe editor; it colors themblue

The Code Body (1)

Columns("A:A").Select Columns("A:A").Select

Selection.Copy Selection.Copy

Columns("D:D").Select Columns("D:D").Select

ActiveSheet.Paste ActiveSheet.Paste

A range of columns(which here is just onecolumn, A) is anobject. It has a methodSelect. This codeactivates the methodto select that column

The Code Body (2)

Columns("A:A").Select Columns("A:A").Select

Selection.Copy Selection.Copy

Columns("D:D").Select Columns("D:D").Select

ActiveSheet.Paste ActiveSheet.Paste

A selection is also anobject. It has a methodcalled Copy. This linecopies the selection(column A) and puts iton the clipboard

The Code Body (3)

Columns("A:A").Select Columns("A:A").Select

Selection.Copy Selection.Copy

Columns("D:D").Select Columns("D:D").Select

ActiveSheet.Paste ActiveSheet.Paste

Change the selectionfrom Column A toColumn D

The Code Body (4)

Columns("A:A").Select Columns("A:A").Select

Selection.Copy Selection.Copy

Columns("D:D").Select Columns("D:D").Select

ActiveSheet.Paste ActiveSheet.Paste

Here the sheet is theobject when we do apaste. This pastes theinformation on theclipboard to theselected place on theactive worksheet

What Is Code?

•The code is a series of instructions to Excel•The code is a series of instructions to Excel

•The instructions are performed in the order given inthe code, so order is critically important•The instructions are performed in the order given inthe code, so order is critically important

•The idea of coding is to write instructions to makeExcel do what you want it to do•The idea of coding is to write instructions to makeExcel do what you want it to do

Saving the Workbook: Save asMacro-Enabled Workbook!

When you reopen, click the Optionsbutton and choose Enable thisContent

One More Macro

•We’ll do the same macro, but this time with the UseRelative References option selected•We’ll do the same macro, but this time with the UseRelative References option selected

•I’m naming this one “Copy4Back”•I’m naming this one “Copy4Back”

•So I will click the relative references option, clickrecord macro, and give the macro a name. Then I willselect Column D, select Column A, copy Column A toColumn D, and stop recording. Then we make abutton for the new macro•So I will click the relative references option, clickrecord macro, and give the macro a name. Then I willselect Column D, select Column A, copy Column A toColumn D, and stop recording. Then we make abutton for the new macro

Here’s what it looks like

After Clicking Copy A toD

If I select Column Dand click Copy 4Back, I get the samething. But if I selectColumn E and clickCopy 4 Back, I getthe next picture.

(I erased Column Dfirst.)

Column B was Copied!

… because Ihad relativereferencesturned on

Slight Problem

•If you look at the code you will see I probably shouldhave named my macro Copy3Back•If you look at the code you will see I probably shouldhave named my macro Copy3Back

•Relative references can be confusing•Relative references can be confusing

•So can copying formulas•So can copying formulas

•In general, the best use of macro recording is for verysimple repetitive tasks, or for finding out what kind ofcode goes with an action (record a macro, then lookat the code)•In general, the best use of macro recording is for verysimple repetitive tasks, or for finding out what kind ofcode goes with an action (record a macro, then lookat the code)

•Next we’ll write our own code•Next we’ll write our own code