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0 pointsuseerup7y ago0 comments

Indeed, in PowerShell you could do:

    1..500 | ?{ !(Test-Path ('{0:0000}_A.csv' -f $_)) }

Explanation:

1..500 generates a sequence of numbers 1 through 500

| pipes the numbers

?{ … } is a filter that is evaluated for each item (number)

! negates the following expression

Test-Path tests that a file exists

-f formats the string left of -f with the parameters (zero-based to the right of -f

'{0:0000}_A.csv' is a pattern which formats parameter 0 as 4 digits, zero-padded.

EDIT: Explanation

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2 comments · 1 top-level

jclay7y ago· 1 in thread

Great example. PowerShell is definitely underrated. I don’t care to use it as an interactive shell, and that likely turns many off to it, but now that it’s cross platform I think it’s massively underrated for these sorts of tasks.

eMSF7y ago

I don't think that example really shows the benefits of the "Powershell way". There's hardly any need for objects and what-not when solving an easy problem like this; strings will do just fine. With Bash, a close equivalent would be:

  for f in {0001..0500}_A.csv; do test -e $f || echo $f; done

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