Is there a function that reverses elements passed via pipeline?
E.g.:
PS C:\> 10, 20, 30 | Reverse
30
20
109 Answers
You can cast $input within the function directly to a array, and then reverse that:
function reverse
{ $arr = @($input) [array]::reverse($arr) $arr
}10, 20, 30 | Sort-Object -Descending {(++$script:i)}Here's a remarkably compact solution:
function Reverse
{ [System.Collections.Stack]::new(@($input))
}Here's one approach:
function Reverse ()
{ $arr = $input | ForEach-Object { $_ } [array]::Reverse($arr) return $arr
}Using $input works for pipe, but not for parameter. Try this:
function Get-ReverseArray { Param( [Parameter(Mandatory = $true, Position = 0, ValueFromPipeLine = $true)] $Array ) begin{ $build = @() } process{ $build += @($Array) } end{ [array]::reverse($build) $build }
}
#set alias to use non-standard verb, not required.. just looks nicer
New-Alias -Name Reverse-Array -Value Get-ReverseArrayTest:
$a = "quick","brown","fox"
#--- these all work
$a | Reverse-Array
Reverse-Array -Array $a
Reverse-Array $a
#--- Output for each
fox
brown
quick$array = 10,20,30; (($array.Length - 1)..0) | %{ $array[$_] }I realize this doesn't use a pipe, but I found this easier if you just wanted to do this inline, there is a simple way. Just put your values into an array and call the existing Reverse function like this:
$list = 30,20,10
[array]::Reverse($list)
# print the output.
$listPut that in a PowerShell ISE window and run it the output will be 10, 20, 30.
Again, this is if you just want to do it inline. There is a function that will work for you.
You can use Linq.Enumerable.Reverse, but it's hard work. Either of the following work:
,(10, 20, 30) | % { [Linq.Enumerable]::Reverse([int[]]$_) }
,([int[]]10, 20, 30) | % { [Linq.Enumerable]::Reverse($_) }The two challenges are putting the whole array into the pipeline rather than one element at a time (solved by making it an array of arrays with the initial comma) and hitting the type signature of Reverse (solved by the [int[]]).
Try:
10, 20, 30 | Sort-Object -Descending
