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Base Conversion Utility

by Adam (Vicar)
on Aug 09, 2000 at 23:04 UTC ( #27148=sourcecode: print w/ replies, xml ) Need Help??

Category:
Author/Contact Info Adam
Description: This was spawned from the code in RE: RE: RE: Randomizing Unique ID? and is a subroutine that you are welcome to steal. It allows base conversions to and from base 10 to any base from 2 to 62. (less then 2 would be pointless.) It only handles non-negative integers, as I didn't feel like exploring the realm of sign bits, twos-complement, and mantissas. Enjoy.
# Change the base representation of a non-negative integer
use strict;
sub GenerateBase
{
    my $base = shift;
    $base = 62 if $base > 62;
    my @nums = (0..9,'a'..'z','A'..'Z')[0..$base-1];
    my $index = 0;
    my %nums = map {$_,$index++} @nums;

    my $To = sub
    {
        my $number = shift;
        return $nums[0] if $number == 0;
        my $rep = ""; # this will be the end value.
        while( $number > 0 )
        {
            $rep = $nums[$number % $base] . $rep;
            $number = int( $number / $base );
        }
        return $rep;
    };

    my $From = sub
    {
        my $rep = shift;
        my $number = 0;
        for( split //, $rep )
        {
            $number *= $base;
            $number += $nums{$_};
        }
        return $number;
    };

    return ( $To, $From );
}

=Example usage:

my( $ToBase62, $FromBase62 ) = GenerateBase( 62 );
my $UniqueID = $ToBase62->( $$ ) . $ToBase62->( time );

my $hex = (GenerateBase(16))[0];
print $hex->( '28' );

=cut

Comment on Base Conversion Utility
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RE: Base Conversion Utility
by Cirollo (Friar) on Aug 10, 2000 at 02:24 UTC
    What about base pi?? {grin}
      I don't think pi is an int.
        What?? Does this mean that pi != 3??
Re: Base Conversion Utility
by ikegami (Pope) on Oct 29, 2008 at 03:46 UTC
    I had need of this recently, but the syntax is overly complicated. The use of code refs is unnecessary.
    { my @nums = (0..9,'a'..'z','A'..'Z'); my %nums = map { $nums[$_] => $_ } 0..$#nums; sub to_base { my $base = shift; my $number = shift; return $nums[0] if $number == 0; my $rep = ""; # this will be the end value. while( $number > 0 ) { $rep = $nums[$number % $base] . $rep; $number = int( $number / $base ); } return $rep; } sub fr_base { my $base = shift; my $rep = shift; my $number = 0; for( $rep =~ /./g ) { $number *= $base; $number += $nums{$_}; } return $number; } }

    You examples becomes

    my $UniqueID = to_base( 62, $$ ) . to_base( 62, time );
    print to_base( 16, 28 );

    If you need your original syntax for some reason, just add

    sub GenerateBase { my $base = shift; return ( sub { to_base( $base, $_[0] ) }, sub { fr_base( $base, $_[0] ) }, ); }

    Then the user has the choice of syntax at no cost.

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