#!/usr/bin/perl


use strict;


##################################################
#file:  <intro.pl>
#This program takes in 4 numbers and calculates the sum using two methods
#To use it, at the command line type perl numbers.pl number_1 number_2 number_3 number_4
#date:  <Dec 21, 2003>
#
#Author:  <Christina Chen>
##################################################

#declare variables
my $num1;
my $num2;
my $num3;
my $num4;
my $total1;
my $total2;
my $i;
my $count;
my @numbers;
my %animals;


#check number of arguments
if($#ARGV != 3) 
{
        print "perl numbers.pl num1 num2 num3 num4\n";
        exit(0);
}


#read in numbers;
$num1=$ARGV[0];
$num2=$ARGV[1];
$num3=$ARGV[2];
$num4=$ARGV[3];


#calculate sum of inputs
$total1=$num1+$num2+$num3+$num4;
print "\nUsing scalars, the sum is $total1\n\n";


#construct an array from the command line

for($i=0;$i<@ARGV;$i++)
{
	
    push @numbers, $ARGV[$i];
	$count++;
	print "The loop has executed $count times.\n";
	print "The array" . ' @numbers ' . "now contains:  @numbers\n\n";
	
}

#doing calculation with elements in an array
for($i=0;$i<@numbers;$i++)
{
        $total2+=$numbers[$i];
}
print "The sum using an array is $total2!!\n\n";