Need help Using compare-object

February 25, 2024

I have these 2 arrays and I need to get the differences between them

$traceIhave = "3226,3042"
$traceIneed =  "3042, 3226, 4199, 7745,8121"

Compare-Object $traceflagsIhave $traceineed

I want that show what is missing from traceIneed to traceihave which is 4199, 7745,8121

Even if I use as integer

$traceIhave = 3226,3042
$traceIneed =  3042, 3226, 4199, 7745,8121

Compare-Object $traceIhave $traceineed

returns

InputObject SideIndicator
----------- -------------
   3042 =>           
   3226 =>           
   4199 =>           
   7745 =>           
   8121 =>           
3226 3042 <=

Can Compare-object do this ?

>Solution :

You can use Compare-Object for this task but you would need to split by comma , those strings so the cmdlet can compare both arrays. Trim() is also used to remove any extra whitespace from each item in the arrays:

$traceIhave = '3226,3042'
$traceIneed = '3042, 3226, 4199, 7745,8121'

Compare-Object $traceIhave.Split(',').Trim() $traceineed.Split(',').Trim()

# InputObject SideIndicator
# ----------- -------------
# 4199        =>
# 7745        =>
# 8121        =>

If you’re interested only in the numbers you could use -PassThru here.

Looking at the edit, it seems what you actually have in $traceIhave is actually an array within an array or an unenumerated array. This could happen if the cmdlet you’re using outputs this array without enumerating it.

Example:

$traceIhave = , (3226, 3042)
$traceIneed = 3042, 3226, 4199, 7745, 8121

Compare-Object $traceIhave $traceineed

# InputObject SideIndicator
# ----------- -------------
#         3042 =>
#         3226 =>
#         4199 =>
#         7745 =>
#         8121 =>
# {3226, 3042} <=

The way you could deal with this is to pipe to Write-Output to unroll the array. If $traceIhave is the result of a command, you can directly pipe it after your command, example:

$traceIhave = (Invoke-Sqlcmd2 -ServerInstance . -Database master -Query "DBCC TRACESTATUS").traceflag | Write-Output

Using the example from before:

$traceIhave = , (3226, 3042) | Write-Output
$traceIneed = 3042, 3226, 4199, 7745, 8121

Compare-Object $traceIhave $traceineed

# InputObject SideIndicator
# ----------- -------------
#        4199 =>
#        7745 =>
#        8121 =>

Looking at the newly added screenshot to the question, the only possible explanation for that behavior is that some point your variable $traceIhave was constrained to a [string], i.e. [string] $traceIhave = ..... in which case the solution would have been to constrain it back to an [int[]]: [int[]] $traceIhave = .....