Question

I’m using Access 2010 under Win7. I’ve discovered I can dimension my arrays at run-time by simply invoking ReDim arrayName(x) without first declaring the array as Dim arrayName().

Sub FooBar()
   ReDim myArray(2)
   myArray(0) = "This is the first string in myArray."
   myArray(1) = "This is the second string in myArray."
   myArray(2) = "And this is the last string in myArray."
   MsgBox myArray(0) & vbCrLf & myArray(1) & vbCrLf & myArray(2)
End Sub

Is there any reason I should NOT use this shortcut?

Cheers!

Answer 1

That’s interesting. This MSDN page confirms what you’re seeing: Here’s a quote:

“You can use the ReDim statement to declare an array implicitly within
a procedure. Be careful not to misspell the name of the array when you
use the ReDim statement. Even if the Option Explicit statement is
included in the module, a second array will be created.”

This page explains that Redim creates a new array and that the existing array is copied into it (assuming there is one):

http://msdn.microsoft.com/en-us/library/w8k3cys2%28v=vs.80%29.aspx

As to your question, should you do it, I’d say no, because it’s confusing, and does open your code to errors that Option Explicit won’t catch.

Reasonably enough, Redim Preserve doesn’t exhibit this behavior.