You're printing $line - can't you see that it is not numeric and thus can't be used as an array index?

One way is by changing the for loop (and some other modifications to improve your code):

use strict;
use warnings;

open my $HOSTS, "<", "/etc/hosts" or die "Cannot open hosts file!\n";
my @hosts = <$HOSTS>;
close $HOSTS;

for my $line (0..$#hosts) {
    if ($hosts[$line] =~ /($ARGV[0])/) {
        print "$hosts[$line]";
        delete $hosts[$line]
    }
}

[download]

In reply to Re: deleting a non-numeric scalar within array by VinsWorldcom
in thread deleting a non-numeric scalar within array by pipeops

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.