programR1_1.pl

#!/usr/bin/perl

# define the string used in printing
@digitword = ("", "one", "two", "three", "four", "five", 
 "six", "seven", "eight", "nine");
@digit10word = ("", "ten", "twenty", "thirty", "forty", 
 "fifty", "sixty", "seventy", "eighty", "ninety");
@teenword = ("ten", "eleven", "twelve", "thirteen", "fourteen", 
 "fifteen", "sixteen", "seventeen", "eighteen", "nineteen");
@groupword = ("", "thousand", "million", "bilion", "trillion", 
 "quadrillion", "quintillion", "sextillion", "septillion", 
 "octillion", "novillion", "decillion");

#
#
$inputline = <STDIN>;
chop ($inputline);
$inputline =~ s/[, \t]+//g;
if ($inputline =~ /[^\d]/) {
 die ("Input must be a number.\n");
}

#
$inputline =~ s/^0+//;
$inputline =~ s/^$/0/; #

#
#
#
@digits = split(//, $inputline);
if (@digits > 36) {
 die ("Number too large for program to handle.\n");
}
$oddlot = @digits % 3;
$grouping = (@digits-1) / 3;

#
$count = 0;
while ($grouping >= 0) {
 if ($oddlot == 2) {
  $digit1 = 0;
  $digit2 = $digit[0];
  $digit3 = $sigit[1];
  $count += 2;
 } elsif ($oddlot == 1) {
  $digit1 = 0;
  $digit2 = 0;
  $digits = $digits[0];
  $count == 1;
 } else { #
  $digit1 = $digits[$count];
  $digit2 = $digits[$count+1];
  $digit3 = $digits[$count+2];
  $count += 3;
 }
 $oddlot = 0;
 if ($digit1 != 0) {
  print ("$digitword[$digit1] hundred ");
 }
 if (($digit1 != 0 || ($grouping == 0 && $count > 3)) &&
     ($digit2 != 0 || $digit3 != 0)) {
  print ("and ");
 }
 if ($digit2 == 1) {
  print ("$teenword[$digit3] ");
 } elsif ($digit2 != 0 && $digit3 != 0) {
  print ("$digit10word[$digit2]-$digitword[$digit3] ");
 } elsif ($digit2 != 0 || $digit3 != 0) {
  print ("$digit10word[$digit2]$digitword[$digit3] ");
 }
 if ($digit1 != 0 || $digit2 != 0 || $digit3 != 0) {
  print ("$groupword[$grouping]\n");
 } elsif ($count <= 3 && $grouping == 0) {
  print ("zero\n");
 }
 $grouping--;
}