#!/usr/bin/perl
#
# Name : Matthew Reeves
#
# Converts a binary number to decimel
#
#use diagnostics;
use warnings;
use strict;
#use feature ":5.10";

#prompt user for binary number to be converted, chomp $input
print "\nPlease enter a binary number: ";
chomp(my $input = <>);

#declares and sets initial values for variables
my $tmp = "";
my $count = 0;
my $decimel = 0;
my $binary = $input;

#loop to process binary-decimel conversion. Chops off digits
#from input from right to left, checks if digit is 1 or not,
#and if it is, raises 2 to the appropriate power based on the 
#value of $count, and adds result to current value for $decimel
#then increments $count. Loop runs until $binary = empty string.
while ($binary ne "")
{
	$tmp = chop $binary;

	if ($tmp == 1)
	{
		$decimel+=2**$count;
	}

	$count++;	
}

#prints original value, and converted value to screen
print "$input is $decimel in decimel.\n\n";

#I see now why you said arrays would be overkill for this assignment,
#the array implementation I coded first was way more complex that this.