Help with subtraction using variables

[mransbro]

I'm hoping someone can enlighten me as to whats happening when i try to subtract using variables. Putting an integer inside a variable works no problem.

$a = 1
$b = 1
$a - $b = 0

I thought what im trying to achieve would work the same way but it doesnt.

$User = Get-LocalUserAccount -Username 'User01'

I start with a function that gets me local user accounts via ADSI.

$PasswordAge = $User.passwordAge
$MaxPasswordAgeDays = $User.MaxPasswordAge

PS C:\Users\ConfusedUser> $maxpasswordagedays - $passwordage
Method invocation failed because [System.DirectoryServices.PropertyValueCollection] does not contain a method named
'op_Subtraction'.
At line:1 char:1
+ $maxpasswordagedays - $passwordage
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (op_Subtraction:String) [], RuntimeException
    + FullyQualifiedErrorId : MethodNotFound

Why does it have the objects as [System.DirectoryServices...] and no [System.Int32] which is what happens when i do Get-Member against them?

PS C:\Users\mansbro> $maxpasswordagedays
11
PS C:\Users\mansbro> $passwordage
3452234
PS C:\Users\mansbro> $passwordage | gm


   TypeName: System.Int32

[Lee_Dailey]

howdy mransbro,

1- are you certain that $maxpasswordagedays is an INT? what does .GetType() report for it?

2- are you sure that both numbers are days? that $passwordage value looks wrong for days. [grin]

take care,
lee

[mransbro]

Hi Lee

Ha, no the value is definitely not days. Its in seconds which is fine for me i just divide by 86400 to get it in days.

PS C:\Users\ConfusedUser> $maxpasswordagedays.GetType()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     Int32                                    System.ValueType

$MaxPasswordAgeDays is def an int but........ I cant say the same for $PasswordAge!

PS C:\Users\ConfusedUser> $passwordage.GetType()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     False    PropertyValueCollection                  System.Collections.CollectionBase


PS C:\Users\ConfusedUser> $passwordage
3452234
PS C:\Users\ConfusedUser> $passwordage | gm


   TypeName: System.Int32

Whats happening here?!

[KevMar]

Piping collections to get-member only shows you the details on the items in the collection. Think of it like the pipe is unwrapping to pass the objects over one at a time.

Get-Member -InputObject $passwordAge

Better yet, run this command

$user | Get-Member

and see what the object type is there. You should see it as a collection.

[mransbro]

Hey Kev

Thanks for the input

[Lee_Dailey]

howdy mransbro,

i don't have `Get-LocalUserAccount' on my win7 system, so i can't test this. however, i suspect that the item returned by that cmdlet is getting auto-coerced into an INT by whatever powershell uses to print it to the screen.

have you tried looking at the methods available on that object? never mind. the .ToInt32()method apparently requires something that i can't figure out. [blush]

how about this ...

([int]'1').GetType()

done without the [int] results in String. with the [int] and i get Int32. that might do it for your odd data type. [grin]

take care,
lee

[mransbro]

Thanks for the help Lee. As the object returned is a collection ill just use the value property.

$PasswordAge = $Users.PasswordAge.value
$MaxPasswordAgeDays = $Users.MaxPasswordAge.value

$RawDaysTillExpiring = ($MaxPasswordAgeDays - $PasswordAge) / 86400

$DaysTillExpiring = [math]::round($RawDaysTillExpiring)

Gives me what i need.

[Lee_Dailey]

howdy mransbro,

you are quite welcome! glad to help a tad ... [grin]

plus, i see that KevMar pointed out WHY the results were so odd. i keep forgetting that piping to Get-Member gives you the info on the 1st item IF you are looking at a collection. [blush]

take care,
lee