Hons on the #Powershell IRC channel (@irc.freenode.net) asked this:
“how do I create an array of a specific size? Like in VBScript: ”dim array 20)”, so that I can immediately index into the array”
He went on to explain that he knows a for loop (see below) would work, but he was looking for the quick way.
$array = @(0), for (x=0 to 19) { $array += 0 }
Here is what I came up with:
$array = ,0 * 20
Pro: It’s quick
Con: Sure looks funny…
A bit more tweaking came up with this:
$arr = @(0) * 20
I think we’ll call this the “final answer”. 
@(123) * 100 works and it has the upside of initializing the collection to a specific value, however if you just want to allocate space, you can do this efficiently with the New-Object cmdlet:
PS (52) > $a = new-object object[] 10
PS (53) > $a.count
10
PS (54) > $a = new-object int[] 30
PS (55) > $a.count
30
-bruce [MSFT]
Ahh, very good. I just reviewed the help file for new-object and I have to say this usage is not extremely obvious. Guess that’s why we have books like “Powershell in Action”.
An other option using a static method of the Array class :
PoSH> [array]::CreateInstance([object],5)
PoSH> $a = [array]::CreateInstance([int],5)
PoSH> $a
0
0
0
0
0
PoSH> $a[2] = ‘foo’
Array assignment to [2] failed: Cannot convert value “foo” to type “System.Int
rror: “Input string was not in a correct format.”.
Greetings /\/\o\/\/
[...] Then Bruce Payette followed up with more info which was awesome, so click the link to see that. http://halr9000.com/article/430 method 1: $array = ,0 * 20 method 2: $array = @(0) * 20 — Author, Tech Prosaic blog [...]