Difference between ForEach and ForEach-Object in powershell

foreach-object powershell
powershell foreach-object multiple commands
powershell nested foreach-object
foreach-object powershell csv
powershell foreach -parallel
foreach in foreach powershell
how foreach loop works in powershell
powershell foreach-object if

Is there any difference between ForEach and ForEach-Object ?

I have a small code like this, works fine

$txt = Get-Content 'C:\temp\000.txt'
$result = foreach ($line in $txt) {$line.replace(".ini","")}
$result | out-file 'c:\temp\001.txt'

But if i use 'ForEach-Object', I got errors....

$txt = Get-Content 'C:\temp\000.txt'
$result = foreach-object ($line in $txt) {$line.replace(".ini","")}
$result | out-file 'c:\temp\001.txt'

Why ? and how to output the loop results by using ForEach-Object

foreach is an alias of ForEach-Object but it appears to also be a keyword (which is confusing).

The foreach ($<item> in $<collection\>){<statement list>} syntax you are using is help about_foreach.

The foreach as ForEach-Object alias is help ForEach-Object.

The keyword foreach operates over each $<item> in the $<collection> as given in the () bit.

The alias foreach/function ForEach-Object operates over each item of the collection it receives as input.

Getting to Know ForEach and ForEach-Object, Summary: Learn the differences between ForEach and ForEach-Object in Windows PowerShell. Honorary Scripting Guy and Windows  There are two variants of ‘for each’ in PowerShell: Foreach statement: iterates over a collection of objects ForEach-Object: obtains its entries from the pipeline At first they both seemed to do the job, but there are some differences. Let’s do a test with a simple array of items and loop through it using

They're different commands for different purposes. The ForEach-Object cmdlet is used in the pipeline, and you use either $PSItem or $_ to refer to the current object in order to run a {scriptblock} like so:

1..5 | ForEach-Object {$_}

>1
>2
>3
>4
>5

Now, you can also use a very similiar looking keyword, ForEach, at the beginning of a line. In this case, you can run a {scriptblock} in which you define the variable name, like this:

ForEach ($number in 1..5){$number}
>1
>2
>3
>4
>5

The core difference here is where you use the command, one is used in the midst of a pipeline, while the other starts its own pipeline. In production style scripts, I'd recommend using the ForEach keyword instead of the cmdlet.

ForEach-Object, the example above, the $i variable represents the iterator or the value of each item in $path as it iterates over each element in the array. ForEach-Object (with its aliases % and ForEach) take input from the pipeline. Although it is slower to process everything, it gives you the benefit of Begin, Process, and End blocks. In addition, it allows you to stream the objects to another command via the pipeline.

Both the previous answers are correct, but https://blogs.technet.microsoft.com/heyscriptingguy/2014/07/08/getting-to-know-foreach-and-foreach-object/ has both a good summary:

When you are piping input into ForEach, it is the alias for ForEach-Object. But when you place ForEach at the beginning of the line, it is a Windows PowerShell statement.

and more details:

The ForEach statement loads all of the items up front 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.

He then includes some performance measurements and concludes:

So which one do you use? Well, the answer is, "It depends." You can iterate through a collection of items by using either the ForEach statement or the ForEach-Object cmdlet. ForEach is perfect if you have plenty of memory, want the best performance, and do not care about passing the output to another command via the pipeline. ForEach-Object (with its aliases % and ForEach) take input from the pipeline. Although it is slower to process everything, it gives you the benefit of Begin, Process, and End blocks. In addition, it allows you to stream the objects to another command via the pipeline. In the end, use the approach that best fits your requirement and the capability of your system.

What does $_ mean in PowerShell?, foreach is an alias of ForEach-Object but it appears to also be a keyword (which is confusing). The foreach ($<item> in $<collection\>){<statement list>} syntax  Neither 'For' nor ForEach can handle piping; to execute this classic (|) PowerShell technique, you need a cmdlet called ForEach -Object . The key to appreciating the difference between ForEach and ForEach-Object is to make the connection between the noun 'Object' and (|) piping.

Apart from the technical differences that have been mentioned before, here are some practical differences, for sake of completeness (see also):

1.) In a pipeline, you do not know the total count of the processed items. This is a situation where you would opt to acquire the complete list first and then do a foreach-loop.

Example:

$files = gci "c:\fakepath"
$i = 0
foreach ($file in $files) {
    $i++
    Write-Host "$i / $($files.Count) processed"
}

2.) With an existing list, the foreach loop is faster than then pipeline version, because the script block does not have to be invoked each time. (But the difference might be negligible depending on the work you do and the number of items.)

Example:

$items = 0..100000
Measure-Command { $items | ForEach-Object { $_ } }
# ~500ms on my machine
Measure-Command { foreach ($i in $items) { $i } }
# ~70ms on my machine

PowerShell Foreach Loop & ForEach-Object, difference between ForEach and foreach? A. PowerShell has two different ForEach's. The first is a cmdlet named ForEach-Object that is part  The PowerShell ForEach Loop can be used to iterate through a set of items collected in a PowerShell variable. The ForEach-Object function can be used to work with objects directly. Here are some examples.

The PowerShell foreach Loop: Examples, Demos and Learning, My understanding is foreach is alias of foreach-object – which I can confirm by explain why there is a difference in behaviour, is it a bug or expected behaviour? they could be an alias for a Cmdlet called Foreach-Object. An important difference between foreach as a keyword (looping construct) and the command/cmdlet ForEach-Object, is that the keyword/loop generates the entire collection specified in the pipeline before processing it.

Difference between ForEach and ForEach-Object in powershell , of the difference between Foreach and Foreach-Object: Foreach-Object object in the Duration: 5:15 Posted: Sep 26, 2017 ForEach will load the whole array at once where ForEach-Object is intended to have a data stream piped to it.The Hello, I am writing a function where I create a PsObject. I add members to this object using a loop.First of all I get EmailAddresses property of a mailbox.

ForEach vs foreach with PowerShell, There are two variants of 'for each' in PowerShell: Foreach statement: iterates ForEach-Object: obtains its entries from the pipeline. At first they both seemed to do the job, but there are some differences. Let's do a test with a  Before jumping on to bug I noticed in my code, I just want to brief what is the difference between Foreach loop statement and Foreach-Object that we generally use via pipe line. If you look at the aliases for Foreach-Object cmdlets, you will see both foreach and %. That means foreach is nothing but an alias to Foreach-Object.

Comments
  • social.technet.microsoft.com/Forums/en-US/…
  • well, if i change the code to ForEach-Object, I get error Unexpected token 'in' in expression or statement. Missing closing ')' in expression. Unexpected token ')' in expression or statement. .......
  • Right. Because ForEach-Object doesn't use that syntax. Look at the help documents I listed.
  • Keywords : ForEach-Object used in the pipeline. nice.
  • ForEach can also be piped to, because it's also an alias for ForEach-Object. (But the reverse is not true - ForEach-Object is not a keyword and can't be used for loops.)