Hashtables and key order

Question

Is there a way to keep the order of keys in a hashtable as they were added? Like a push/pop mechanism.

Example:

$hashtable = @{}  $hashtable.Add("Switzerland", "Bern") $hashtable.Add("Spain", "Madrid") $hashtable.Add("Italy", "Rome") $hashtable.Add("Germany", "Berlin") $hashtable 

I want to retain the order in which I've added the elements to the hashtable.

Answer 1

There is no built-in solution in PowerShell V1 / V2. You will want to use the .NET System.Collections.Specialized.OrderedDictionary:

$order = New-Object System.Collections.Specialized.OrderedDictionary $order.Add("Switzerland", "Bern") $order.Add("Spain", "Madrid") $order.Add("Italy", "Rome") $order.Add("Germany", "Berlin")   PS> $order  Name                           Value ----                           ----- Switzerland                    Bern Spain                          Madrid Italy                          Rome Germany                        Berlin 

In PowerShell V3 you can cast to [ordered]:

PS> [ordered]@{"Switzerland"="Bern"; "Spain"="Madrid"; "Italy"="Rome"; "Germany"="Berlin"}  Name                           Value ----                           ----- Switzerland                    Bern Spain                          Madrid Italy                          Rome Germany                        Berlin