brant_chen has asked for the wisdom of the Perl Monks concerning the following question:

I want to print a reversed array from STDIN,
This works:
#----------------------------------
#Pass
@temp=<STDIN>;
chomp(@temp);
@new1=reverse(@temp);
foreach $new(@new1) {
    $new = "\t$new";
    print $new."\n";
}
#----------------------------------

[download]

But why this doesen't:
#----------------------------------
@getnew=reverse(chomp(@temp=<STDIN>));
foreach $new(@getnew) {
    $new = "\t$new";
    print $new."\n";
}

[download]

Thank you.

Replies are listed 'Best First'.
Re: basic question:how to print a reversed array from STDIN
by ikegami (Patriarch) on Dec 04, 2008 at 10:23 UTC

    Because chomp "returns the total number of characters removed from all its arguments."

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Re: basic question:how to print a reversed array from STDIN
by ccn (Vicar) on Dec 04, 2008 at 11:09 UTC

    You also may try the following funny onliner script 

    perl -pe '$\=$_.$\}{'

    [download]

    Yes, it prints reversed array of lines from STDIN

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Re: basic question:how to print a reversed array from STDIN
by holli (Abbot) on Dec 04, 2008 at 12:25 UTC
    The reason why is what ikegami said. So try this: 
    @getnew=reverse(map { chomp; $_} <STDIN>);

    [download]
    or 
    chomp(@temp=<STDIN>);
@getnew=reverse(@temp);

    [download]
    Whatever you like best. I prefer the first version.


    holli, /regexed monk/
[reply]
[d/l]
[select]
      I think this is neater: 
      chomp(@getnew = reverse <STDIN>);

      [download]
[reply]
[d/l]
      I cringe when I see map or grep modify $_.
[reply]
[d/l]
[select]
        I agree with you in regards to grep, but map? It's sole purpose is the modification of $_.


        holli, /regexed monk/
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Re: basic question:how to print a reversed array from STDIN
by poolpi (Hermit) on Dec 04, 2008 at 14:14 UTC
[reply]
[d/l]
      Three bugs:
      • It doesn't print the last character of the input if the line has no line ending.
      • It doesn't print a trailingleading zero.
      • It's a poor way of achieving the goal.
[reply]

        Dear ikegami,

        I had never have the intention to submit this little piece of code to Perl 6 core modules...

        For me, it was just a funny variation on chomp.

        To be constructive, please give some examples because i can't reproduce two of your three remarks

        Laziness, impatience, hubris and why not humility.

        hth,
        PooLpi

        'Ebry haffa hoe hab im tik a bush'. Jamaican proverb
[reply]
[d/l]

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