Marshall++ for pointing out the most obvious solution. However, since it is possible that you have simplified what you are trying to accomplish, here are three alternatives.You can decide which is best.

sub display_paragraph() {
   my $aref = shift;
   my $indentation = shift;
   my $first_time = 0;        # declare and init a flag
   for my $line (@$aref) {
      if (++$first_time == 1) {     # change and test the flag
         print ' ' x $indentation;
      }
      print "$line\n";
   }
}

[download]
use 5.010;
sub display_paragraph() {
   my $aref = shift;
   my $indentation = shift;
   for my $line (@$aref) {
      state $first_time = 0;        # declare and init a flag
      if (++$first_time == 1) {     # change and test the flag
         print ' ' x $indentation;
      }
      print "$line\n";
   }
}

[download]
sub display_paragraph() {
   my $aref = shift;
   my $indentation = shift;
   while (my ($index, $line) = each @$aref) {
      if ($index == 0) {     # test the position
         print ' ' x $indentation;
      }
      print "$line\n";
   }
}

[download]

In reply to Re: Easiest way to do something only on first iteration of loop by Mr. Muskrat
in thread Easiest way to do something only on first iteration of loop by ibm1620

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.