#PSTip Getting information about a collection object, not its elements

You have a collection of values in a variable. When you pipe the variable to the Get-Member cmdlet you get the type and members of each item in that collection. PowerShell unrolls the collection and sends each item through the pipeline, one at a time, to the Get-Member cmdlet.

PS> $array = "one",2
PS> $array | Get-Member
   TypeName: System.String
Name             MemberType            Definition
----             ----------            ----------
Clone            Method                System.Object Clone(), System.Object ...
CompareTo        Method                int CompareTo(System.Object value), i...

   TypeName: System.Int32
Name        MemberType   Definition
----        ----------   ----------
CompareTo   Method       int CompareTo(System.Object value), int CompareTo...
Equals      Method       bool Equals(System.Object obj), bool Equals(int o...

Most of the time that’s the desired output. However, there are cases where you’ll need to get the members of the collection itself. To do so, you can choose one of three approaches. Call the GetType method on a variable:

PS> $array.GetType()
IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     Object[]                                 System.Array

Pass the collection object to the InputObject parameter of the Get-Member cmdlet:

PS> Get-Member -InputObject $array
   TypeName: System.Object[]
Name           MemberType            Definition
----           ----------            ----------
Count          AliasProperty         Count = Length
Add            Method                int IList.Add(System.Object value)
Address        Method                System.Object&, mscorlib, Version=4.0.0...
Clear          Method                void IList.Clear()
Clone          Method                System.Object Clone(), System.Object IC...
CompareTo      Method                int IStructuralComparable.CompareTo(Sys...

Or use the unary comma operator to create an array with one member. That way when the array is unrolled the inner array will pass through the pipeline as one item.

PS> ,$array | Get-Member
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