convert_num_system.pl

#! /usr/bin/perl

###############################################################################
# convert between numeric systems                                     BnGhTz  #
#                                                                             #
# Usage: convert_num_system.pl number from [to]                               #
#  number: number to convert                                                  #
#  from:   base radix (int 2 - 36)                                            #
#  to:     target radix (int 2 - 36); The default is 10.                      #
#                                                                             #
# Examples:                                                                   #
# ./convert_num_system.pl foo 25                                              #
# 9999                                                                        #
#                                                                             #
# ./convert_num_system.pl 301 36 7                                            #
# 14224                                                                       #
#                                                                             #
###############################################################################

###### INCLUDES ###############################################################
use strict;
use warnings;

###### VARS ###################################################################
my $ver = 'v.0.0.1';
my $name = (split(/\/|\\/, $0))[-1];
my $max_radix = 36;
my $min_radix = 2;

###### SUBS ###################################################################
sub usage(;$)
{
  my $txt = (defined $_[0]) ? '' : $_[0];
  die "Usage: $name number from [to]\n\n" .
      "  number: number to convert\n" .
      "  from:   base radix (int $min_radix - $max_radix)\n" .
      "  to:     target radix (int $min_radix - $max_radix); The default is 10.\n\n";
}

sub check_radix($)
{
  my $x = shift;

  return undef if $x =~ /\D/;
  return 1 if (($x !~ /\D/) && ($x >= $min_radix) && ($x <= $max_radix));
}

sub dec_to_chr($)
{
  return $_[0] > 9 ? chr($_[0] + ord('A') - 10) : $_[0];
}

sub chr_to_dec($)
{
  my $x = uc($_[0]);
  return ($_[0] =~ m/^\D$/) ? ord($x) - ord('A') + 10 : $_[0];
}

sub search_min($)
{
  my $ret = 0;

  while ($_[0] =~ m/(.)/g)
  {
    my $x = chr_to_dec($1) + 1;
    $ret = $x if $x > $ret;
  }

  return $ret;
}

sub scale_to_dec($$)
{
  return scale_to_any(@_, 10);
}

sub scale_to_any($$$)
{
  my ($num, $from, $to) = @_;

  return 0 if $num eq '0';

  my $min = search_min($num);
  die "Invalid radix '$from'. Minimal radix is '$min'\n" if ($min > $from);

  my @nums = $num =~ m/(.)/g;
  my $ret = '';

  # to 10;
  my $_10 = 0;
  for (my $i = 0; $i <= $#nums; $i++)
  {
    $_10 += chr_to_dec($nums[$#nums - $i]) * $from ** $i;
  }

  # to oth;
  if ($to == 10 && 0)
  {
    $ret = $_10;
  }
  else
  {
    while ($_10)
    {
      my $c = $_10 % $to;
      $_10 = ($_10 - $c) / $to;
      $c = dec_to_chr($c) if $c > 9;
      $ret =  $c . $ret;
    }
  }

  return $ret;
}

###### PROGRAM ################################################################

# inputs
my ($number, $from, $to) = @ARGV;

usage() if (
  (!defined($from) || !check_radix($from)) ||
  (defined($to) && !check_radix($to))
);

if ($number =~ /^-/)
{
  $number =~ s/^-//;
  warn "cannot handle negative number\nretest with: $number\n\n";
}

$to ||= 10;

my $out = scale_to_any($number, $from, $to);
print "$out\n" if defined($out);