Powershell: Use variable from inner loop as condition of outer loop - powershell

Question

we're using a PS-Script for creating new AD-users and configure everything in one go.
I'd like to create a unique 6-digit number and check if it's already in use.
I thought a do-until-loop will do the trick, but i can't get it to re-run if a match is found.
My code as of now is this:
$AllUsedPins=(Get-ADUser -Properties ExtensionAttribute3 -Filter {ExtensionAttribute3 -like '*'} | select -ExpandProperty ExtensionAttribute3)
do{
$PinIsUnique="True"
#$TempPin="333860"
$TempPin=(Get-Random -Minimum 0 -Maximum 999999).ToString('000000')
foreach ($UsedPin in $AllUsedPins) {
If ("$TempPin" -eq "$UsedPin" ) {
$PinIsUnique="False"
Write-Host '$PinIsUnique(IF): '$PinIsUnique
}
}
Write-Host '$PinIsUnique(inDO): '$PinIsUnique
}
until ($PinIsUnique="True")
Write-Host '$PinIsUnique(outDO): '$PinIsUnique
#Set-ADUser -Identity $sam -Replace #{extensionAttribute3=$TempPin}
$TempPin="333860" is for testing, as it is one already used. The loop should then run endlessly, but stops after one run nevertheless, so I added some Write-Outputs to narrow it down. They show:
$PinIsUnique(IF): False
$PinIsUnique(inDO): False
$PinIsUnique(outDO): True
$TempPin: 333860
What puzzles me here:
$PinIsUnique is only set at the beginning of the do-loop, before that it doesn't even exist.
$PinIsUnique is False until end of the do-loop, but True when used for checking the while-condition?
I wasted by far too much time on this already: Reading up on loops in general, nested loops, global variables, return, Write-Host vs Write-Output and other things that sounded as they could help me solve this...
I altered the code for easier testing as nearly half of all options should trigger at least one re-run:
$AllUsedPins=("01", "02", "03", "04", "05", "11", "12", "13", "14", "15")
do{
$PinIsUnique="True"
$TempPin=(Get-Random -Minimum 0 -Maximum 20).ToString('00')
foreach ($UsedPin in $AllUsedPins) {
If ("$TempPin" -eq "$UsedPin" ) {
$PinIsUnique="False"
}
}
}
until ($PinIsUnique="True")
Write-Host '$AllUsedPins: '$AllUsedPins
Write-Host '$TempPin: '$TempPin
As i realized just now while trying the altered code, $TempPin is useable outside the do-loop just fine... So what am I missing here?
Some litte extra if someone cares:
I tried to stop the inner foreach-loop if an existing pin was found, but couldn't get that to work either. Neither break nor a labeled break worked... at least the way i tried.
Also, as i'm no expert in scripting/programming but can usually identify a well-written piece of code: How would you guys have solved this?
Thanks in advance!

Answer 1

Sometimes you just have to talk about a problem to get to the solution... and to be ashamed of yourself...
Just edited
until ($PinIsUnique="True")
to
until ($PinIsUnique -eq "True")
and it works just fine...
Other examples of how to solve it are encouraged, while i'm standing in the corner facing the wall...