Hashtable vs array of user objects in relation to iteration

Question

I often write lists of things and do enumerations against them to do some get / set.

I hate listing hash tables, because whenever I need it, I have to lean back to work with hashtable objects.

 $hashtablelistofitems = @{} $hashtablelistofitems.add("i'm a key", "i'm a value") foreach ($item in $hashtablelistofitems.keys) { $item $hashtablelistofitems.item($item) } 

Instead, I usually revert to using a one-dimensional array of a custom object with two non-elements.

 $array = @() $listofitems = "" | select key,value $listofitems.key = "i'm a key" $listofitems.value = "i'm a value" $array += $listofitems foreach ($item in $listofitems) { $item.key $item.value } 

Why should I use hashtable on this method? Just because it guarantees only one value per key?

Answer 1

You should use a hash table if you want to save a list of key values, and not create an array containing a custom object with two properties (key / values), mainly for two reasons:

• You might want to pass your hash table to a function that expects a hash table.
• Hashtable is the built-in PowerShell type that users are aware of. Your second approach is harder to read / maintain for other users.

Note: You can iterate over a hash table in much the same way as your approach by calling the GetEnumerator() function:

 foreach ($item in $listofitems.GetEnumerator()) { $item.key $item.value } 

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In addition, the hash table comes with convenient methods that you can use:

 @{} | Get-Member | Where-Object MemberType -eq Method | Select Name 

Output:

 Name ---- Add Clear Clone Contains ContainsKey ContainsValue CopyTo Equals GetEnumerator GetHashCode GetObjectData GetType OnDeserialization Remove ToString 

Answer 2

This is not as useful as Martin's compilation, but it is quite useful.

This is an MSDN article on how to convert back and forth between Hashtables and PSCustomObjects. Article