Correct me if I'm wrong, but shouldn't the below change each element in the array $List to 'ZZZ'?

> $List = @('a','b')
> ForEach($i In $List) { $i = 'ZZZ' }
> $List
a
b

Correct me if I'm wrong, but shouldn't the below change each element in the array $List to 'ZZZ'?

> $List = @('a','b')
> ForEach($i In $List) { $i = 'ZZZ' }
> $List
a
b

• powershell
• foreach
• reference-type

Share Improve this question Follow edited Mar 26 at 20:07 Santiago Squarzon 61.6k55 gold badges2424 silver badges5454 bronze badges asked Mar 26 at 18:55 Ryan.JamesRyan.James 5755 bronze badges

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1 Answer 1

Sorted by: Reset to default 2

It would if you were dealing with mutable reference types, e.g. an array of hash tables:

$List = @{ Value = 'a' }, @{ Value = 'b' }
foreach ($i in $List) { $i.Value = 'ZZZ' }
$List

The loop modifies the original hash tables in $List because $i is a reference to each hash table, and hash tables are mutable reference types.

But for value types and strings in this case, which are reference types but are immutable, the assignment of $i doesn't change the string itself, just re-assigns the variable reference to a new string.

If you used a for loop instead of a foreach for example, and since arrays are also reference types, you could alter their elements, but again, this doesn't mean you're altering the strings themselves, just assigning a new reference to each array element.

$List = 'a', 'b'
for($i = 0; $i -lt $List.Length; $i++) { $List[$i] = 'ZZZ' }
$List