Understanding Foreach and Foreach-object in Powershell
Posted by Superadmin on January 29 2023 05:29:09

Understanding Foreach and Foreach-object in Powershell

 

 

Foreach and Foreach-object are subject of discussion lately and we have a word for it. Looping is the core of any code or script and we have to make sure to do it correctly. But ever wonder which one fits better to run certain codes on multiple servers. Let’s check this out in this post and grab some useful knowledge. 

 

 

 

 

Head to Head: Foreach-object and Foreach

Foreach is one of the rising-star when chosen between invoke-command and where { }.
The advantage of having foreach is that we can store value under one string in excel which is a boon. Likewise, we get 2 different options while choosing foreach (), 1 is foreach itself and the other is foreach-object. But when you see the object it looks similar doesn’t it.
Well I have performed a test so that we can pick our winner.
 
ForEach-Object is best used when sending data through the pipeline because it will continue streaming the objects to the next command in the pipeline, for example.

Speed Test between Foreach-object and Foreach

Test Code below: This will test how much time it actually takes for the loops to complete.

 Contents 
Head to Head: Foreach-object and ForeachSpeed Test between Foreach-object and ForeachThe Verdict: Which to use?
$a=Get-ChildItem –File C:\users\dhrub\ -Recurse
$time = (Measure-Command {

   $a | ForEach-Object {

        $_

    }

}).TotalMilliseconds

 [pscustomobject]@{

    Type = 'ForEach-Object'

    Time_ms = $Time

 }
 $Time = (Measure-Command {

    ForEach ($i in ($a)) {

        $i

    }

}).TotalMilliseconds

  [pscustomobject]@{

    Type = 'ForEach'

    Time_ms = $Time

 }

 Output:

 Type            Time_ms
----            -------
ForEach-Object 213.3006
ForEach         64.8013

The Output will surely shock you !

 

 

 

 

The Verdict: Which to use?

The ForEach statement loads all of the items upfront into a collection before processing them one at a time. 

ForEach–Object expects the items to be streamed via the pipeline, thus lowering the memory requirements, but at the same time, taking a performance hit.

Forach will be always faster than Foreach-object but this doesn’t determine you don’t use foreach-object. It always depends upon the requirement of the work.