Returning a value from within a ForEach in Powershell

Question

This seems really basic, but I can't see how or why it behaves this way:

function ReturnStuff{
    $a=1,2,3,4,5
    $a.ForEach{
        return $_
    }
}

ReturnStuff

Why does this give me: 1 2 3 4 5 instead of just 1?

xXhRQ8sD2L7Z · Accepted Answer · 2016-06-01 01:54:12Z

15

It looks like you are calling ForEach (a function in [System.Array]) with a parameter which is a scriptblock. Essentially, you are defining and returning { Return $_ } every iteration of the loop.

This means ReturnStuff will capture output each time, and because this function does nothing with the output of this line, all the output is returned:

$a.ForEach{ return $_ }

This behavior is similar to $a | Foreach-Object { return $_ }

So what to do?

Use a ForEach loop instead (not to be confused with Foreach-Object):
```
ForEach ($item In $a) { return $item }
```
Select the first value returned from all the scriptblocks:
```
$a.ForEach{ return $_ } | Select -First 1
```

answered Jun 1, 2016 at 1:54

xXhRQ8sD2L7Z

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2 Comments

Ben Power Over a year ago

Wow, that's one hell of a trap for newbies! Thanks!

mhenry1384 Over a year ago

Doesn't make any sense to me why they work differently. Isn't the ForEach loop (option #1) also being called with a parameter which is a scriptblock?

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