Powershell doesn't return key value in hashtable - powershell

Question

PS C:\Users\kris> $hashx=#{}
PS C:\Users\kris> $(Get-CimInstance Win32_Process | Select-Object ProcessId, Name) | ForEach-Object { $hashx[$_.ProcessId]=$_.Name }
PS C:\Users\kris> $hashx
Name Value
---- -----
1292 svchost.exe
6032 StartMenuExperienceHost.exe
428 smss.exe
4736 powershell.exe
2580 svchost.exe
5628 explorer.exe
5164 taskhostw.exe
PS C:\Users\kris> $hashx['5164']
PS C:\Users\kris> $hashx.5164
PS C:\Users\kris> $hashx."5164"
PS C:\Users\kris> $hashx.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Hashtable System.Object
Can anyone explain me what i do wrong? i'm beginner in powershell, and i don't understand why it returns null value by key?

Answer 1

Get-CimInstance Win32_Process returns ProcessId property as type System.UInt32. You will need to cast your key retrieval values to that type or convert the ProcessId values to System.Int32. The reason is by default the shell interprets unquoted or uncast whole numbers as System.Int32 provided the number is less than or equal to [int32]::maxvalue or System.Int64 otherwise.
In your case, you can simply use the syntax below if you don't mind working with Uint32:
$hashx[[uint32]5164]
Personally, I would convert the ProcessId value to System.Int32 (using accelerator [int]) when adding it to the hash table:
Get-CimInstance Win32_Process |
Select-Object ProcessId, Name | ForEach-Object {
$hashx[[int]$_.ProcessId] = $_.Name
}
# Now the keys can be accessed using Int32 numbers
$hashx[5164]
As an aside, you can discover property types yourself with the Get-Member command:
Get-CimInstance win32_Process |
Select -First 1 -Property ProcessId | Get-Member
TypeName: Selected.Microsoft.Management.Infrastructure.CimInstance
Name MemberType Definition
---- ---------- ----------
Equals Method bool Equals(System.Object obj)
GetHashCode Method int GetHashCode()
GetType Method type GetType()
ToString Method string ToString()
ProcessId NoteProperty uint32 ProcessId=0
Notice the definition of ProcessId shows type uint32.