In support of this Thread post
https://www.excelforum.com/excel-pro...ml#post5397531
Option Explicit and variable declaration
Hello
You can easily find lots of information on the internet that can explain Option Explicit , ( just a few examples given in the Refs below). But my take on it for you:
The simple answer to your specific question is that its not necessary, its just personal choice.
It’s all related to the issue of declaring variables – its difficult to discuss the issue of Option Explicit without discussing the variable declaration issue: In VBA it is not necessary to declare variables. If you use a variable, without an initial declaration, then it will be created “on the fly” as you use them. Mostly they will then be given the Variant type
What a code line at the top of a code module, of Option Explicit , does, is enable the option of being explicit for variable declaration. In other words, it forces you to declare all your variables: If you have this code line at the top of your code module, but then in any coding don’t declare any variable, you will get a warning error, on attempting to run your macro.
Simple Examples
Lets say you make a simple Typo, and write MyMsg , when you meant MyMsig. The following macro won’t error, but it wont give the answer you may have expected.
Sub Testit()
_Let MyMsig = "Hello"
_MsgBox Prompt:=MyMsg
End Sub
https://i.imgur.com/WwnXByf.jpg
There’s nufin there in that Message Box! – Why? – The message box is using variable MyMsg: The variables MyMsig and MyMsg were created “on the fly”, as you used them, but MyMsg has not been used yet. There is no error, but you did not get to be warned of your likely typo of writing MyMsg instead of MyMsig
The next 2 macros would warn you of undeclared variables with a compile error on attempting to run them
Option Explicit
Sub Testit()
_Let MyMsig = "Hello"
_MsgBox Prompt:=MyMsg
End Sub
https://i.imgur.com/LlXPOfj.jpg
That last macro did not catch your Typo, but if you corrected that missing declaration for MyMsig, then you would still go on to get the warning of the non declared MyMsg
Option Explicit
Sub Testit()
Dim MyMsig As String
_Let MyMsig = "Hello"
_MsgBox Prompt:=MyMsg
End Sub
https://i.imgur.com/D9KsQuG.jpg
In fact, in the last macro you would have had the possibility to notice your mistake whilst writing the code line
MsgBox Prompt:=mymsg , provided that you had written it in lower case:
If you had written it just like that, lowercase, mymsg, - having done that, then mymsg would have stayed lowercase when you moved on to writing the next line. On the other hand, If any variable had been declared using any Uppercase characters, then on writing that variable name in lower case characters, and then moving on to the next line, that previous code line would have been changed automatically by the VB Editor to show the correct variable word, including any capital characters.
So an additional point from that experiment is that, if you do choose to declare your variables, then its worth considering using at least one capital in your variable name, but then going on when writing the variable further in the macro to use just lower case always. The VB Editor should automatically correct all your variables, ( and incidentally also correct any commands you type in lower case ) to their correct form including any upper case characters: So, if something remains lower case when you move on to writing the next code line, then you have an immediate indication that something is probably wrong, ( mostly*** ).
( The automatic capitalisation is not directly related to using Option Explicit, but is related to the issue of declaring variables. The use of Option Explicit is mostly of consideration when considering how you choose to handle your variable usage).
So you have a couple of good reason to choose to use Option Explicit and declare your variables carefully.
But you do not have to use Option Explicit
Most people prefer to declare all variables, and to use Option Explicit
There are some people , amongst them respected professionals who go against the trend, don’t use Option Explicit, and consider the use of declaration only where really needed, for example when working when working with class modules. The reasoning is usually given as to avoid redundancy in coding, keeping coding as efficient as possible.
Its personal choice. Do anyfin ya wanna do :)
Molly
Ref:
http://www.eileenslounge.com/viewtop...265556#p265556
http://www.eileenslounge.com/viewtopic.php?f=30&t=2281
*** Unfortunately life is not so simple with Microsoft. A bug can cause the automatic capitalization to fail. If you notice this, for example when known commands stay lowercase, then the only known cure seems to be to restart Excel and/ or your computer.
