Math::BaseConvert with strange basenumbers like 23 or 1000 - perl

Question

I just found the perl module Math::BaseConvert. I have to the task to convert numbers to very strange number with a different base. Not only base 2, 8, 16, but also 23, 134 up to 1000. (This is a partial task to balance a tree of files in a directory)
I could not make it. Reading the tests for the module in CPAN also confused me. So I wrote a little test, maybe you can tell me what's wrong, the result is:
ok 1 - use Math::BaseConvert;
ok 2 - Convert number '23' (base10) to '27' (base8)
not ok 3 - Convert number '23' (base10) to '23' (base32)
# Failed test 'Convert number '23' (base10) to '23' (base32)'
# at test_math_baseconvert.pl line 35.
# got: 'N'
# expected: '23'
not ok 4 - Convert number '64712' (base10) to '64:712' (base1000)
# Failed test 'Convert number '64712' (base10) to '64:712' (base1000)'
# at test_math_baseconvert.pl line 35.
# got: '-1'
# expected: '64:712'
1..4
# Looks like you failed 2 tests of 4.
The testprogram is this:
#!/usr/bin/perl
use strict;
use warnings;
use Test::More;
use_ok( 'Math::BaseConvert', '1.7' );
my #lines = (
{
# http://www.wolframalpha.com/input/?i=23+from+base+10+to+base+16
old_number => '23',
old_base => 10,
new_number => '27',
new_base => 8,
},
{
# http://www.wolframalpha.com/input/?i=23+from+base+10+to+base+32
old_number => '23',
old_base => 10,
new_number => '23', # stays same
new_base => 32,
},
{
# http://www.wolframalpha.com/input/?i=64712+from+base+10+to+base+1000
old_number => '64712',
old_base => 10,
new_number => '64:712',
new_base => 1000,
},
);
for my $line (#lines) {
cmp_ok(
Math::BaseConvert::cnv(
$line->{old_number}, $line->{old_base}, $line->{new_base}
),
'eq',
$line->{new_number},
sprintf(
"Convert number '%s' (base%d) to '%s' (base%d)",
$line->{old_number}, $line->{old_base},
$line->{new_number}, $line->{new_base}
)
);
}
done_testing();

Answer 1

Wolfram Alpha's method of showing bases greater than base 16 is to separate digits with a colon. There's nothing wrong with that, as they're displaying those numbers using css styling that lessons the shading of the colon to make it more obvious what they're doing. But they also add a message stating exactly how many digits they're showing since "1:1617 (2 digits)" isn't obvious enough.
The method Math::BaseConvert and other such modules use is to expand the character set for digits just like is done with hex numbers 0-9A-F to include the first 6 letters in the alphabet. For the case of base 32 numbers the character set is 0-9A-V. Given N is the 14th letter in the alphabet, it is the appropriate representation for 23 in base 32.
If you want to use the colon representation for numbers greater than 16, you can either use the module or just roll your own solution.
#!/usr/bin/perl
use strict;
use warnings;
use Test::More;
use_ok( 'Math::BaseConvert', '1.7' );
my #lines = (
# Old_Number Old_Base New_Number New_Base
[qw(23 10 27 8)], # http://www.wolframalpha.com/input/?i=23+from+base+10+to+base+16
[qw(23 10 23 32)], # http://www.wolframalpha.com/input/?i=23+from+base+10+to+base+32
[qw(64712 10 64:712 1000)], # http://www.wolframalpha.com/input/?i=64712+from+base+10+to+base+1000
);
for my $line (#lines) {
cmp_ok(
base10toN(#$line[0,3]),
'eq',
$line->[2],
sprintf("Convert number '%s' (base%d) to '%s' (base%d)", $line->[0], 10, #$line[2,3])
);
}
sub base10toN {
my ($num, $base) = #_;
return Math::BaseConvert::cnv($num, 10, $base)
if $base <= 16;
my #digits = ();
while (1) {
my $remainder = $num % $base;
unshift #digits, $remainder;
$num = ($num - $remainder) / $base
or last;
}
return join ':', #digits;
}
done_testing();

Answer 2

You seem to be expecting decimal output, with "digits" being decimal numbers separated by :.
Math::BaseConvert doesn't do that. It only supports having a single character per digit.
By default, the digits used are '0'..'9', 'A'..'Z', 'a'..'z', '.', '_' though you can supply your own list instead (and you would have to do so to support up to base 1000).