It looks like you want to create a series of timestamps, one for each day in the @day_of_Month array. After fixing the initialization as indicated by Bloodnok, you just need to loop through the days: 
use strict;
use warnings;
use Time::Local;
my @day_Of_Month = ( 5, 16, 20 );
#i want to use this array one by one to do unix time stamp

use Time::Piece;
my $t = localtime($^T);
printf "entire time:  %s\n", $t;
printf "Month: %s\n",        $t->month;
printf "Year:  %s\n",        $t->year;

for my $dayOfMonth (@day_Of_Month) {
    my $updatetime = timegm(59,59,23,$dayOfMonth, $t->_mon, $t->year);
    printf "time for %2d  %d  (%s)\n", $dayOfMonth, $updatetime,
      scalar gmtime($updatetime);
}

#time for  5  1391644799  (Wed Feb  5 23:59:59 2014)
#time for 16  1392595199  (Sun Feb 16 23:59:59 2014)
#time for 20  1392940799  (Thu Feb 20 23:59:59 2014)

[download]

In reply to Re^3: convert it to unix time stamp by sn1987a
in thread convert it to unix time stamp by oikool

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.