Creating Your First VBA Program
In the first part of this blog series we saw how to get into the VB Editor
application and insert a module. You're now ready to start writing your
first VBA program!
Creating a Subroutine
The most common type of program you're likely to write in VBA is called a
subroutine, or sub for short. You can start writing a
subroutine by typing the word sub at the top of the module you
created earlier (we're using Excel for this demonstration).
Type in the word
sub, followed by a space to get started with your subroutine.
You'll hear lots of words used to refer to a subroutine - program, procedure,
macro, and sub for instance. They all mean essentially the same thing - a
set of instructions that an application will follow when you run the subroutine.
The next thing you need to do is type in a name for your subroutine.
Names for subroutines follow the same rules as names for projects and modules:
don't use spaces and try to avoid punctuation characters. If you can make
the name of your program unique and descriptive then all the better! The
program we're going to write in this first example will simply create a new
Excel workbook and write a title into cell A1 on the first worksheet.
We'll call our subroutine CreateAndLabelNewFile. Type
this into your module after the word sub.
Notice we've typed in the word
sub in lowercase letters, but used uppercase letters to start each word in the name of the subroutine. This is a common convention used in VBA programming to make it easier to read the names of things.
The only other thing you need to do to create your subroutine is to press Enter
on the keyboard, so do just that!
Congratulations, you've created a subroutine! Obviously it
doesn't actually do anything yet, but we're getting to that
part.
Assuming that you didn't see an error message,
several things should happen automatically when you press the Enter
key:
- The word sub is capitalised to Sub.
- The word Sub is coloured in dark blue.
- A set of parentheses is added to the end of the subroutine
name.
- The words End Sub appear on the line below
your text cursor.
All of these things are important, but the VB Editor does the work for you -
it's like a more helpful and fancy version of the Notepad application.
If something went wrong and you saw an error message when you pressed Enter,
the two most likely reasons are:
1. You put a space or other disallowed character in the name.
2. You typed in a name that is reserved by the VBA language.
If you see this error message, just click OK and make sure that your
sub's name doesn't contain any spaces or punctuation characters.
So far, the code that we've written doesn't actually perform any useful
actions. That's something we'll solve in the next article in this series,
but first you should learn a little about how to lay out your code neatly.
The Importance of Neat Code Layout
Once you've created your subroutine, you can start typing the VBA code on the
very next line. The problem with doing this is that when you come back to
look at your code later you'll find yourself staring at a horrible looking chunk
of text that's very difficult to read.
You can make your life much easier by using blank lines to separate parts of
your code, and indenting text within a subroutine to make it easier to see where
it starts and ends. To do this, once you've created your subroutine by
pressing Enter, press Enter
once more to create a blank like, and then press Tab
on the keyboard to indent your code.
|
|
|
Your text cursor should start here... |
...and end here. |
It may seem like a pedantic thing to do, and technically speaking it's not
even necessary, but it will definitely make your life easier in the long run.
Trust us! You can hopefully see the benefits of this approach by comparing
the two screenshots below (even if you don't understand the actual code!).
|
|
|
Without a neat layout to the code it's extremely difficult to work out what's
going on in this subroutine. |
The simple addition of a few blank lines and indents makes the whole subroutine
much easier to read. |
Adding Comments to Your Code
Another thing that will help you enormously when looking at your code later
is a series of comments that explain what your program does. You can add a
comment either on a separate line or at the end of a line of code by typing an
apostrophe. You can then type whatever you like and press Enter
at the end of the line to create the comment.
|
|
|
After the apostrophe, type in your comment. |
Press Enter and the text will turn dark green to indicate that it's a comment. |
You can see more information on the art of commenting code here.
It might seem like a lot of effort, but you'll thank yourself for doing it later
on!
Now that we've created a subroutine and laid out our code properly, we're
ready to start writing some real code. Read the next part of this series
to learn how.
