The Next Step Beyond the Macro Recorder in VBA Programming
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The macro recorder is a good introduction into the world of VBA programming, but it's not meant to be your only teacher. It provides a simplistic approach to coding with Excel’s object model, but is by far not a teacher of advanced or efficient programming methods. You can even pick up some bad habits if you rely on it as your only means of learning VBA. Like many other programmers, I did start off with the recorder but eventually moved to the next level.
Here are 10 things I had to learn to take my programming skill up a notch.
1. The Macro Recorder Is a Terrible Teacher, But You Can Learn from It.
I'm not saying to throw out the recorder and never use it again. In truth, most of the time I find it more useful then Microsoft’s help files when I need to look up an object or its properties and methods. Need the code for creating a pivot table? Then go ahead and record it so you can see the objects and steps involved. But then improve the code by using the advice below.
2. Declare Your Variables!
In the early days when RAM was so expensive, every byte counted. That was a major argument for declaring variables: Undeclared variables are of type variant, with a minimum size of 16 bytes, whereas if you declare a variable as type integer, you use only 2 bytes.
Now that high RAM is so common, some have thrown out the argument and don’t bother declaring variables. But then, they’ve forgotten the other reason for variable declaration, one which has saved me a lot of frustration: When you require variable declaration, Excel will point out unknown variables during compilation. And if you mix upper-and lowercase in your variable naming, you can spot mistakes right away, because Excel will keep the case the same for you as you are typing your code.
You have to manually turn on the variable declaration requirement: In the VBE, go to Tools, Options and check the box for Require Variable Declaration. Once that’s done, any new workbooks will have Option Explicit at the top of every module. For your older workbooks, you can type in Option Explicit at the top of a module, forcing variable declaration.
3. There’s No Need to Use Select or Activate.
Probably one of the worst actions the recorder teaches is that objects must be selected before they can be manipulated. If you provide Excel with the specific object you want to manipulate, such as a sheet name or cell address, then you don’t need to activate the sheet or select the cell. So, while the macro recorder provides this:
Sheets("Sheet1").Select
Range("A1").Select
ActiveCell.FormulaR1C1 = "5"
Range("A2").Select
ActiveCell.FormulaR1C1 = "6"
Range("A3").Select
ActiveCell.FormulaR1C1 = "=SUM(R[-2]C:R[-1]C)"
All that’s really needed is this:
Sheets("Sheet1").Range(“A1”).Value = 5
Sheets("Sheet1").Range(“A2”).Value = 6
Sheets("Sheet1").Range("A3").Formula = "=SUM(A1:A2)"
Not only does this shorten the number of lines, but it also makes it easier to read the code because right away you know what object (Sheet1, cell A1) is being modified. Changing FormulaR1C1 to Value is mainly a style preference; I prefer to use FormulaR1C1 when actually entering an R1C1-style formula. The change to Formula in the last line is also personal; I’m an A1-style gal, most of the time. By including the sheet object (Sheets("Sheet1")) each time, it doesn’t matter what sheet is actually the active sheet. Excel will always update Sheet1. This is a great way to hide data you’re entering from users.
4. Indent Your Code to Improve Readability.
It seems to be such a small matter, but indention of loops goes a long way in making code easier to read. Whenever someone posts unindented code at a forum, the first thing I do is indent it
5. Get the Last Row and Last Column of a Data Set.
Even when you use keyboard shortcuts to select the last row and column of your data set, the recorder returns a specific range. Of course, this means the next time you run your macro, it may miss some data. Even if you think your data will always be the same size, it’s a good idea to get in the habit of having Excel find the last row and column. It doesn’t take it very long to calculate the information, and it makes your code more flexible for the future.
The following code sample finds the last row (LastRow) by starting in the very last cell in column A and going up the rows until it finds a value. The last column (LastColumn) is found by starting in the very last cell in row 1 and going left until it finds a value. The range is then bolded and italicized.
Dim LastRow As Long, LastColumn As Long
LastRow = Range("A" & Rows.Count).End(xlUp).Row
LastColumn = Cells(1, Columns.Count).End(xlToLeft).Column
Range("A1").Resize(LastRow, LastColumn).Font.Bold = True
Range("A1").Resize(LastRow, LastColumn).Font.Italic = True
6. Declare Objects for Simpler Code.
In the previous code sample, I had to type the range twice: once to bold it and again to italicize it. Can you imagine if I also wanted to change the number format? Copy it? That’s a lot of typing, and it’s so easy to make a mistake. To avoid these two issues, declare an object.
Declare the object variable as the type of object you want it to be, such as a workbook, a worksheet, or in the case of the previous example, a range. Then use the keyword Set to assign the value to the object.
Dim rng as Range
Set rng = Range("A1").Resize(LastRow, LastColumn)
Once you’ve done that, wherever you reference the wordy range resize statement, use rng instead:
rng.Font.Bold = True rng.Font.Italic = True
This is also very handy when you need to switch between objects, such as sheets. You’ve already learned that you don’t need to activate a sheet to access it, but typing the sheet reference over and over again, especially if you have a long sheet name, can be tedious. Instead, set objects to the sheets and use those references as needed.
In the following example, we have two sheets: one with a data set and the other for the report. The code uses the object references to copy the header from the data sheet to the report sheet.
Dim wksData As Worksheet, wksReport As Worksheet
Set wksData = Worksheets("January Data Dump")
Set wksReport = Worksheets("January Report by Sales")
wksData.Range("A1:C1").Copy wksReport.Range("A1")
When you’re done with the object variables, you want to release them, freeing up system memory but also avoiding possible coding issues later, such as when you want to use the variables again. To do this, set them to Nothing:
Set rng = Nothing Set wksData = Nothing Set wksData = Nothing
7. Use the With..End With Statement for Cleaner Code.
Whether you declare your own objects or not, it can be tiresome to type the same object in one line of code after another. That’s where With..End With can help simplify your code. You only have to specify the object once at the beginning of the statement, and then any lines that need to allude to it, will. For those lines to reference the object, you start those lines with a period (.). In the following sample, the .Name property gets its object reference from the With Worksheets(1) statement. The second With statement also gets its reference from the first With statement, while the .Font.Bold property gets its object from the second With statement.
With Worksheets(1)
.Range("A1").Value = .Name
With .Range("A2")
.Font.Bold = True
End With
End With
8. Split Up Your Code.
There’s nothing wrong with having a thousand lines of code in a single procedure; it’s just a bit difficult to read. If you have a procedure that performs multiple tasks such as importing data, formatting that data, and then calculating with the data, you're better off with taking the code for each task and placing it in its own procedure. You can then create a single procedure that calls the other procedures.
Another reason you want to split up your code is to reduce duplication. Imagine you have a workbook with 100 sheets and you are formatting each sheet the same way. You could have a procedure that formats each specific sheet, one after another, but this would be a long procedure. And when you need to change the formatting, you will have to edit each instance.
A better way to code this would be to have a separate procedure that does the formatting. The formatting procedure has a sheet argument. Your main procedure simply calls the formatting procedure, providing the sheet object as the argument. You might have the same call 100 times, once for each sheet, but when you have to go and update the formatting, all you have to do is update a single procedure.
Sub FormatAllTheSheets()
Dim wks As Worksheet
For Each wks In Worksheets
FormatThisSheet wks
Next wks
End Sub
Sub FormatThisSheet(ByVal wks As Worksheet)
With wks
'...do formatting stuff
End With
End Sub
9. Manage Unhandled Errors.
An unhandled error is one that pops up the debug dialog box. This dialog box can confuse your user, so instead provide an information window and then exit the procedure properly.
The command to enable an error handling routine is On Error GoTo line label. When it runs into an error, the code will jump to the line label and run the code after it.
In the following example, the code includes a line to disable events. If the code runs into an unhandled error, when the user clicks the End button in the dialog box, events remain turned off. Using an error handler, you can turn the events back on and exit the procedure properly.
Sub CalculateSummaries()
Application.EnableEvents = False
On Error GoTo errHandler
'...your procedure code here
GoTo ExitSub 'if the code runs fine, when it reaches here it jumps to the ExitSub label
errHandler: 'if there's an error, the code will jump here
MsgBox "There was an unknown error" & Chr(10) & _
Err.Number & ": " & Err.Description
ExitSub: 'no matter what, the following line will run
Application.EnableEvents = True
End Sub
10. Speed It Up.
There are two ways you can speed up your code. The first involves adding lines of code at the beginning and end of your main procedure. The second method requires processing of data in memory, instead of on the sheet.
There are a couple of lines of code you can include in every project that might help speed it up. Just remember, when you turn something off in Excel you need to turn it back on at the end of the program.
- Application.ScreenUpdating: This is the property behind most of the screen flickering you see when your program runs. By setting this to False, you might be able to speed up the program because Excel doesn’t spend time updating the screen. Just remember to set it back to True at the end of your program.
- Application.Calculation: This is the property behind Excel's calculation mode. By setting it to Manual, you ensure that Excel will only calculate a cell when it is updated. Because the workbook may already be set to Manual or another mode, save the existing mode in a variable, switch to Manual, and at the end the program load the variable back into the property.
Sub MakeItFaster() Dim CalcMode As XlCalculation Application.ScreenUpdating = False CalcMode = Application.Calculation Application.Calculation = xlCalculationManual 'your code Application.ScreenUpdating = True Application.Calculation = CalcMode End Sub
By processing your data in the computer’s memory (for example, by using an array), you can greatly decrease the time it takes for a program to process data. Even with ScreenUpdating turned off, if the code is looping through rows, it takes longer than if it looped through an array. You can go a step further by placing the results of the program into an array and then “dumping” the results onto the sheet once, instead of writing to the sheet for each result. Basically, the less Excel has to interact with the sheet, the faster the program.
The next two examples demonstrate the running time difference between looping and processing in memory. The first procedure loops through 500,000 rows, placing a value in each cell. It took about 14 seconds to run on my machine. Turning off ScreenUpdating didn’t significantly affect the time.
Sub SlowFill()
Dim i As Long
Dim StartTime As Date, EndTime As Date
Application.ScreenUpdating = False
StartTime = Now()
For i = 1 To 500000
Cells(i, 1).Value = i
Next i
EndTime = Now()
Range("B1").Value = Format(EndTime - StartTime, "hh:mm:ss.0 ")
Application.ScreenUpdating = True
End Sub
The second procedure does all the processing in memory using an array and then places the results once on the sheet. It ran in less than one second.
Sub FastFill()
Dim i As Long
Dim arr(1 To 500000, 1 To 1)
Dim StartTime As Date, EndTime As Date
StartTime = Now()
For i = 1 To UBound(arr)
arr(i, 1) = i
Next i
Range("D1").Resize(UBound(arr)).Value = arr
EndTime = Now()
Range("E1").Value = Format(EndTime - StartTime, "hh:mm:ss.0")
End Sub
Final Thoughts
The macro recorder is a good way to begin writing your own code, but as a teacher, it falls a little short. With a few tweaks, you can make your code more efficient, easier to read, and even run faster. These pointers are just the tip of the iceberg when it comes to taking your coding skill to the next level or higher.