Powershell中对foreach的不同输入

Question

I've got two beginner's questions regarding data types in Powershell.

1. why does these two commands differ in results?

    PS > $test = {"a", "b", "c"} PS > foreach ($item in $test) { $item | Out-Host } "a", "b", "c" PS > $test = "a", "b", "c" PS > foreach ($item in $test) { $item | Out-Host } a b c 

2. One command returns data, which - when formatted as list - looks like the following:

    Changes : {Change instance 10406282 ChangeType: Edit (...) , Change instance 25906333 ChangeType: Edit (...) } 

   It looks like this is some kind of a list of items. How can I foreach through them?

Answer 1

First question If you do following: $test = {"a", "b", "c"} $test.GetType()

$test = "a", "b", "c"
$test.GetType()

You will notice that the first object is ScriptBlock the second one is an array

Second question

Assign result to an object and simple iterate as you do above.

Simple example:

$result = (Get-TfsItemHistory $/<projectName> -all -user $name -Recurse -server $tfs)
$result | foreach {$item = $_; Write-Host $item; Write-Host $item.ChangeType;}

Answer 2

{...} creates a scriptblock, you might think that the loop runs 3 times but it's not (one iteration only), it just returns the content of the script block.

Items seperated by a comma creates a collection of items (array). When you loop over a collection you iterate over each item int he collection