Parse string in PowerShell to create output using variables

Question

I want to create little script that takes particular type of string and uses it in a way I can process things easily

%1g.%s which basically means 1 char from given name and full secondary name (output should be j.snow built from 2 parameters)
%g.%s which basically means full given name dot and full secondary name (output should be john.snow built from 2 parameters)
%5g.%s which basically means 5 chars from given name and full secondary name but if given name is shorter use shorter version (john.snow)
%g%s which would given givenname and secondary name without dot (johnsnow)
etc

Question is how do I even start processing it so that I don't create a monster if/else cases? Or should I exactly do that?

EDIT. Since this is Microsoft Exchange Email Template behaviour just wanted to explain this is for Office 365 without on-premise option which doesn't have Email Templates option. In other words I want to create a script that would mimic this behaviour in some way.

Why? Are you trying to reproduce the behavior of email address templates in Exchange? — Bill_Stewart
– Bill_Stewart, Commented Aug 1, 2016 at 17:04
Office 365 doesn't have email templates (except for on-premise), and I wanted to write nice script doing what Exchange Online should have in first place — MadBoy
– MadBoy, Commented Aug 1, 2016 at 17:05
OK, but you didn't say anything about that in your question. — Bill_Stewart
– Bill_Stewart, Commented Aug 1, 2016 at 17:06
There's not really a need to mimic the on-premises Exchange behavior if you can write your own using a regular expression, which would give you a lot more flexibility anyway. — Bill_Stewart
– Bill_Stewart, Commented Aug 1, 2016 at 17:09
Well that's what I am basically asking. I want to do something similar, maybe I'm starting from wrong place.. feel free to give me a hint. — MadBoy
– MadBoy, Commented Aug 1, 2016 at 17:11

TessellatingHeckler · Accepted Answer · 2016-08-01 18:03:20Z

1

$firstName = "Alice"
$lastName = "Bloggs"

$template = '%2g.%[email protected]'

function Get-NameSection {
    # Returns the first $num characters of a name
    # unless $num is 0, missing or longer than the name
    # then returns the entire name

    param([string]$name, [int]$num)

    if (-not $num -or $num -gt $name.Length) { 
        $name 
    } else {
        $name.Substring(0, $num)
    }
}

$template = [regex]::Replace($template, '%(\d*)g', {param($m) Get-NameSection $firstName $m.Groups[1].Value })
$template = [regex]::Replace($template, '%(\d*)s', {param($m) Get-NameSection $lastName $m.Groups[1].Value })

$template

answered Aug 1, 2016 at 18:03

TessellatingHeckler

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1 Comment

MadBoy Over a year ago

Nice! I was about to go by using more static approach but this one is great.

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