Remove-Characters

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.

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))
}

3 comments

  1. 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(‘\ ‘,’|’))”, ”

    Like

    1. 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.

      Like

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