PowerShell/Scripts/write-rot13.ps1

<#
.SYNTAX       write-rot13.ps1 [<text>]
.DESCRIPTION  encodes or decodes the given text with ROT13
.LINK         https://github.com/fleschutz/PowerShell
.NOTES        Author: Markus Fleschutz / License: CC0
#>

param($Text = "")

function ROT13 { param([string]$Text)
	$Text.ToCharArray() | ForEach-Object {
		if ((([int] $_ -ge 97) -and ([int] $_ -le 109)) -or (([int] $_ -ge 65) -and ([int] $_ -le 77))) {
			$Result += [char] ([int] $_ + 13);
		} elseif ((([int] $_ -ge 110) -and ([int] $_ -le 122)) -or (([int] $_ -ge 78) -and ([int] $_ -le 90))) {
			$Result += [char] ([int] $_ - 13);
		} else {
			$Result += $_
		}        
	}
	return $Result
}

try {
	if ($Text -eq "" ) {
		[string]$Text = read-host "Enter text to write"
	}
	$Result = ROT13 $Text
	write-output $Result
	exit 0
} catch {
	write-error "ERROR: line $($_.InvocationInfo.ScriptLineNumber): $($Error[0])"
	exit 1
}