How To Easily Loop And Index In PowerShell

Just learned these bits today while trying to answer something and thought to share them.

Consider these two arrays:

$x = @("a","b","c","d");
$y = @("apple","banana","carrot","dinner");

What I want to see as output is:

a is for apple
b is for banana
c is for carrot
d is for dinner

There are a couple of ways of going about this and then some.

You can use a regular for loop:

for ($i = 0; $i -Lt $x.Count; ++$i)
    "$($x[$i]) is for $($y[$i])";

You can go with a regular foreach loop too this way, if the values in $x are distinct – we’ll get around that in a second:

foreach ($v in $x)
    "$v is for $($y[$x.IndexOf($v)])"

You can shorten it by using a ForEach-Object CmdLet:

$x | ForEach-Object { "$_ is for $($y[$x.IndexOf($_)])" };

You can shorten the ForEach-Object into the % operator:

$x | % { "$_ is for $($y[$x.IndexOf($_)])" };

And finally, you can fix the issue of indexing duplicates by adding an initializer to the foreach and treating it just like a for:

$x | % { $i = 0 } { "$_ is for $($y[$i])"; ++$i };

You learn something new every day.

Index: PowerShell HowTo’s


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