how to use variable in parameter name - powershell

Question

I am trying to read multiple files in powershell script in a for-loop always switching the file name dynamically.
I tried a different notation, but I'm still getting errors.
The code is like:
$fileName1 = "D:\file333"
$fileName2 = "D:\file444"
$datePattern =" C.{3} "
[Char[]]$buffer = new-object char[] 10000
for ($j=1; $j -le 2; $j++)
{
[string]$fileNumber = $j.ToString()
$inFile = new-object -TypeName System.IO.StreamReader -ArgumentList
$fileName($fileNumber)
[int]$bytesRead = $inFile.Read($buffer, 0, $buffer.Length)
while ($bytesRead -gt 0) {
[string]$bufferString = -join $buffer
$results = $bufferString | Select-String $datePattern -AllMatches
$results.Matches.Value
[int]$bytesRead = $inFile.Read($buffer, 0, $buffer.Length)
}
}
I have two questions:
What would be a right notation for the -ArgumentList, to get FileName1 and then FileName2?
Does the Read method applied on the inFile really requires a Char[] type as argument for $buffer? And Is it possible to get the [String] parameter instead?
Can someone give me a hint?

Answer 1

Okay,
I'm sure you were reminded when you first submitted the question, but please remember to put your code in a code block, like so:
$fileName1 = "D:\file333"
$fileName2 = "D:\file444"
$datePattern =" C.{3} "
[Char[]]$buffer = new-object char[] 10000
for ($j=1; $j -le 2; $j++)
{
[string]$fileNumber = $j.ToString()
$inFile = new-object -TypeName System.IO.StreamReader -ArgumentList
$fileName($fileNumber)
[int]$bytesRead = $inFile.Read($buffer, 0, $buffer.Length)
while ($bytesRead -gt 0)
{
[string]$bufferString = -join $buffer
$results = $bufferString | Select-String $datePattern -AllMatches
$results.Matches.Value
[int]$bytesRead = $inFile.Read($buffer, 0, $buffer.Length)
}
}
Now, I'm REALLY unsure of what you're trying to do here. Whatever it is, I strongly suggest you create a well founded question here around it.
In any case, powershell doesn't support the behavior you're trying to create. It's an easy newbie trap to fall into. Oh, I want to find files 1 and 2, so I make a loop and use the iterator, right? Wrong!
You need to loop over a collection containing the files. Powershell doesn't think of the files as part of a collection unless you put it in one.
Try this.
$files = #("D:\file3333", "D:\file444")
$datePattern =" C.{3} "
[Char[]]$buffer = new-object char[] 10000
foreach(file in files)
{
[int]$bytesRead = new-object -TypeName System.IO.StreamReader -ArgumentList $file | $_.Read($buffer, 0, $buffer.length)
while($bytesRead -gt 0)
{
[string]$bufferString = -join $buffer
$results = $bufferString | Select-String $datePattern -AllMatches
$results.Matches.Value
[int]$bytesRead = $inFile.Read($buffer, 0, $buffer.Length)
}
}
Here, we put the files into a collection, and iterate over that collection with a foreach loop. We can collapse your multiple lines to call the file into a buffer stream into one line by using the pipe operator.
I have NO IDEA what you're trying to do in the while loop, so I'd be happy to help you make it a bit more powershell friendly, but you'll have to ask the question you mean to ask before I can do so.