This little function lets you remove characters from a string. The twist is that it takes a character array, and will remove all characters in it from the input string.
This can come in handy if you need to for instance remove all special characters from a string. Please note that I have added a selection of special characters as default value for the Remove parameter.
If you take it for a spin, I’d love to hear your comments about it.
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| function Remove-Characters { | |
| <# | |
| .SYNOPSIS | |
| Remove characters from a string. | |
| .DESCRIPTION | |
| This function will take an array of characters, and will remove | |
| those characters from the input string. | |
| .EXAMPLE | |
| $myString | Remove-Characters | |
| This will remove all 'default' characters from myString. | |
| .EXAMPLE | |
| Remove-Characters -InputString $myString -Remove ([char[]](0..47 + 58..64 + 91..96 + 123..255 | ForEach-Object {[char]$_})) | |
| This will remove all characters in the ASCII table except letters and numbers. | |
| .EXAMPLE | |
| Remove-Characters -InputString $myString -Remove ([char[]](0..47 + 58..64 + 91..96 + 123..[int][char]::MaxValue | ForEach-Object {[char]$_})) | |
| This will remove all special characters with the exception of letters and numbers. NOTE This one is a bit slower than the other two examples. | |
| .INPUTS | |
| System.String | |
| .OUTPUTS | |
| System.String | |
| .LINK | |
| https://communary.wordpress.com/ | |
| .NOTES | |
| This code was translated and adapted from this StackOverflow answer: http://stackoverflow.com/a/1120407/3940558 | |
| Author: Øyvind Kallstad | |
| Date: 11.02.2016 | |
| Version: 1.0 | |
| #> | |
| [CmdletBinding()] | |
| param ( | |
| [Parameter(Mandatory = $true, Position = 0, ValueFromPipeline = $true)] | |
| [ValidateNotNullOrEmpty()] | |
| [string] $InputString, | |
| # Characters to remove. Default value is '!"#¤%&€/()=?`+[]{}@£$\¨^~*-_.:,;<> ' | |
| [Parameter(Position = 1)] | |
| [ValidateNotNullOrEmpty()] | |
| [char[]] $Remove = '!"#¤%&€/()=?`+[]{}@£$\¨^~*-_.:,;<> ' | |
| ) | |
| [char[]]$buffer = New-Object –TypeName System.Char[] –ArgumentList $InputString.Length | |
| $index = 0 | |
| foreach ($character in $InputString.ToCharArray()) { | |
| if (-not ($Remove -contains $character)) { | |
| $buffer[$index] = $character | |
| $index++ | |
| } | |
| } | |
| Write-Output (New-Object –TypeName System.String –ArgumentList ($buffer,0,$index)) | |
| } |
Communary 
Hi Øyvind,
Maybe I’m missing the point, but couldn’t you rather use something like the below instead?:
[char[]]$Remove = ‘!”#¤%&€/()=?`+[]{}@£$\¨^~*-_.:,;’
$inputstring = ‘test!”#¤%&€/()##=?`+[]test{}@£$\¨^~*+*-_.:,;test’
$InputString -replace “$([regex]::Escape($Remove).Replace(‘\ ‘,’|’))”, ”
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Hi Dirk. Thanks for your comment. You most certainly could. That’s the beauty of it isn’t it? Many ways to Rome and all that 🙂 The reason I didn’t use regex was just performance really. I have read that using regex will take quite a bit longer, but you will hardly notice it unless you try it on a really large string.
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Hi Øyvind, very true :-).
In relation to this topic, there is also a very interesting post from Tobias Weltner http://powershell.com/cs/blogs/tobias/archive/2011/04/28/multiple-text-replacement-challenge.aspx not sure if you came across it already.
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