Powershell regular expression match return empty string

Question

I am using regular expression to find strings in Powershell, and match function returns empty string lines as well as matched lines.

For the following four lines of text file input.txt,

[abc]

abc

[123]

123

The code below prints out abc/blank line/123/blank line. I expected it only prints out abc and 123, wonder how this happened.

$readArray = Get-Content(input.txt)
foreach($line in $readArray) {
   $re = [regex] *** // Find the string in bracket

   $key = $re.match($line)
   if($key -ne $null) {
      write-host -$key.group[1].value
   }
}

$re = [regex] *** looks like some kind of mistake. Can you post the actual regex you're using? — briantist
– briantist, Commented Aug 11, 2014 at 1:59

Federico Piazza · Accepted Answer · 2014-08-11 02:41:14Z

1

You can use this regex to get the content within tags:

\[(.*?)\]

Working demo

enter image description here

answered Aug 11, 2014 at 2:41

Federico Piazza

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Andy Arismendi · Accepted Answer · 2014-08-11 03:02:08Z

1

Try this (use select-string) -

Get-Content -FilePath input.txt | 
  Select-String '\[(.+?)\]') | ForEach-Object {$_.Matches[0].Groups[1].Value}

edited Aug 11, 2014 at 3:02

answered Aug 11, 2014 at 2:17

Andy Arismendi

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