#!/usr/bin/perl -w
use strict;
use Date::Business;
#
#  usage: $0 MMYYYY
#  result: third friday business day of the given month, which
#          should be the date equity options expire.
#          Use this for equities only; 
#         
#          Bonds and Futures exp dates are another story alltogether.
die &usage unless defined $ARGV[0];
# 
# perhaps I should verify $ARGV[0] is an int and
# length($ARGV[0] = 5
#
my $prepassed = $ARGV[0];
my $mon       = substr($prepassed, 0, 2);
my $yr        = substr($prepassed, 2, 4);

my $passto    = $yr . $mon . 21 ;

my $d = new Date::Business( DATE => "$passto", );
   while ( $d->day_of_week != 5 ) {
       $d->prevb;
   }
my $retdate = $d->image();

print("$retdate\n");

sub usage() {
    print "\n\t usage:\n\t\tgetExpirationDay.pl MMYYYY\n\t\t";
    print "returns expiration day in YYYYMMDD format\n";
}
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