[powershell] Passing multiple values to a single PowerShell script parameter

I have a script to which I pass server name(s) in $args.

This way I can do stuff to this (these) server(s) using foreach:

.\script.ps1 host1 host2 host3

foreach ($i in $args)
{
    Do-Stuff $i
}

I'd like to add a named optional parameter called vlan. I've tried:

Param(
    [string]$vlan
)

foreach ($i in $args)
{
    Write-Host $i
}
Write-Host $vlan

It works if you pass a -vlan parameter but if you don't then the script auto assigns the last server name to $vlan.

So, how can you pass single or multiple parameters plus an optional named parameter to a PowerShell script?

Ideally, here are valid examples:

.\script.ps1 host1
.\script.ps1 host1 host2 host3
.\script.ps1 host1 host2 -vlan office

Parameters take input before arguments. What you should do instead is add a parameter that accepts an array, and make it the first position parameter. ex:

param(
    [Parameter(Position = 0)]
    [string[]]$Hosts,
    [string]$VLAN
    )

foreach ($i in $Hosts)  
{ 
    Do-Stuff $i
}

Then call it like:

.\script.ps1 host1, host2, host3 -VLAN 2

Notice the comma between the values. This collects them in an array

I call a scheduled script who must connect to a list of Server this way:

Powershell.exe -File "YourScriptPath" "Par1,Par2,Par3"

Then inside the script:

param($list_of_servers)
...
Connect-Viserver $list_of_servers.split(",")

The split operator returns an array of string

One way to do it would be like this:

 param(
       [Parameter(Position=0)][String]$Vlan,
       [Parameter(ValueFromRemainingArguments=$true)][String[]]$Hosts
    ) ...

This would allow multiple hosts to be entered with spaces.