Adding Header to the Variable - powershell

Question

This is probably a dumb question but I cant seem to figure it out. How do I add a header to already existing variable? I have a variable with bunch of strings in it and I am trying to make it so it has a header which will simplify the script later on. Just as an example
$test = 1,2,3,4,5,6
Which comes out to be:
PS C:\windows\system32> $test
1
2
3
4
5
6
Where as what I want it to do is:
PS C:\windows\system32> $test
Numbers
--------
1
2
3
4
5
6
Additionally when implementing for each loop is it possible to add a blank header like to existing variable (from which foreach loop is running) and fill it automatically? for example going from original variable:
Letters Value
------- -----
a 10
b 15
c 23
d 25
To after for each loop:
Letters Value Numbers
------- ----- ------
a 10 1
b 15 2
c 23 3
d 25 4
This is a super generic example but basically i have one object with headers and when using a function someone made I am trying to populate the table with output of that function, the issue is that its returning stuff with no header and just returns the output only so I cant even make a hash table.
Thanks in advance.

Answer 1

In your example, your variable is a list of integers.
That's why there's no header.
If your variable were something else, like, a custom object, it would be displayed with headers.
To make your example a list of custom objects:
$test = 1..6
$test | Foreach-Object { [PSCustomObject]#{Number=$_} }
You can save this back to a variable:
$test = 1..6
$testObjects = $test | Foreach-Object { [PSCustomObject]#{Number=$_} }
If an object has four or fewer properties, it will be displayed as a table.
So you could also, say, make an object with two properties and still get headers.
$test = 1..6
$test | Foreach-Object { [PSCustomObject]#{Number=$_;NumberTimesTwo = $_ * 2} }
If you want to control how any object displays in PowerShell, you'll want to learn about writing formatters. There's a module I make called EZOut that makes these a lot easier to work with.

Answer 2

To offer an alternative to Start-Automating's helpful answer:
You can use Select-Object with calculated properties:
To turn a list of numbers into objects ([pscustomobject] instances) with a .Number property, whose display formatting defaults to the tabular display you're looking for:
$objects =
1,2,3,4,5,6 | Select-Object #{ Name='Number'; Expression={ $_ } }
Outputting $objects yields:
Number
------
1
2
3
4
5
6
You can use the same technique for adding additional properties to (copies of) existing objects, filling them at the same time (builds on the $objects variable filled above):
# Values for the new property.
$nums = 6..1 # same as: 6, 5, 4, 3, 2, 1
$i = #{ val = 0 } # Helper hashtable for indexing into $nums
$objects | Select-Object *, #{ Name='NewProperty'; Expression={ $nums[$i.val++] } }
Output:
Numbers NewProperty
------- -----------
1 6
2 5
3 4
4 3
5 2
6 1
If you want to add a property with $null values first and fill them later, use:
$objects | Select-Object *, NewProperty