#!C:/perl/bin/perl.exe
use CGI::Carp qw(fatalsToBrowser);
use CGI;
$query = new CGI;

$pass= $query->param('pass');
$v1= $query->param('v1');
$v2= $query->param('v2');
$v3= $query->param('v3');
$v4= $query->param('v4');

if($pass < 1){
	$pass = 0;
}

print $query->header;
print $query->start_html(-title=>'Subroutines');

print "<style type='text/css'>	body{ font-size: 90%; font-family: verdana; }</style>";


if($pass == 1){

	print "The input values were = $v1, $v2, $v3, and $v4 <BR>";
	$average = &averageScores($v1,$v2,$v3,$v4);
	print "<BR>The average of those values is $average.";

}

if($pass == 0){

	print "<FORM ACTION = '/cgi-bin/P593/sub3.pl' METHOD = 'post'>";

	print "Type 4 numbers below and click the button to find their average.<BR>";
	
	print "<INPUT TYPE=textbox NAME=v1 SIZE=2 MAXSIZE=2><BR>";
	print "<INPUT TYPE=textbox NAME=v2 SIZE=2 MAXSIZE=2><BR>";
	print "<INPUT TYPE=textbox NAME=v3 SIZE=2 MAXSIZE=2><BR>";
	print "<INPUT TYPE=textbox NAME=v4 SIZE=2 MAXSIZE=2><BR>";

	print "<INPUT TYPE=submit VALUE='average'>";
	print "<INPUT TYPE=hidden NAME=pass VALUE=1>";

	print "</FORM>";



}

print $query->end_html;

# ----------------- Subroutines -----------------------------
# for a good tutorial/overview of Perl subroutines, see
# http://www.comp.leeds.ac.uk/Perl/subroutines.html
#------------------------------------------------------------

sub averageScores {

	# Function for averaging scores and adjusting denom for missing cases
	# R. Chris Fraley March 26 2005; modified March 2011
	# Returns the mean, takes as param an array or seq of values
	# Returns zero if no valid cases
	# defined = http://www.perl.com/doc/manual/html/pod/perlfunc/defined.html
	
	$nSUB = @_;
	$validnSUB = 0;
	$sumSUB = 0;
	for($iSUB=0;$iSUB<=($nSUB-1);++$iSUB){

		print "i = $iSUB, $_[$iSUB], ";					# provide index values for internal testing
		

		if($_[$iSUB]){
			print " valid value ";
			$sumSUB = $sumSUB + $_[$iSUB];				# add the value to the running total
			$validnSUB = $validnSUB + 1;				# update the demoninator by 1
			print "Current index value = $iSUB, Running total = $sumSUB, Running denominator = $validnSUB";		# print some testing feedback

		}

		print "<BR>";


	}
	$mean = 0;
	if($validnSUB > 0){
		$mean = $sumSUB/$validnSUB;
	}
    return $mean;
}