in reply to Re: Binary string to base64
in thread Binary string to base64

Thanks for the suggestion:

Working within Math::BigInt, it is easy to make the integer by prepending the string with '0b'. Then, between Math::Base85 and Math::BigInt, it is easy to go back and forth, though one needs to prepend '0's after the decoding to get back to the original length. 

use Math::Base85 qw(from_base85 to_base85);

$str = '0b000000010010001101000101011001111000100110101011110011011110
+1111';

$bint = Math::BigInt->new($str);
$b85str = to_base85($bint);
$bint2 = from_base85($b85str);
print $bint2->as_bin();

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This does exactly what I want now. And I get slightly more efficiency than with base64.

-albert

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Re^3: Binary string to base64
by zentara (Cardinal) on Jun 16, 2006 at 21:21 UTC
    Hi, I was working on the same thing, but I added a '0b1' so that the leading zeroes in the binary wouldn't get truncated. It condenses it down to 10 characters. Here's my attempt: 
    #!/usr/bin/perl
use Math::BigInt;
use Math::Base85;

my $str = '00000001001000110100010101100111100010011010101111001101111
+01111';
print "$str\n";

#prepend a 0b1 to signal binary and contain leading zeroes  
my $str_p = '0b1'.$str;
print "$str_p\n\n";

my $bignum = Math::BigInt->new($str_p);

my $hex =  $bignum->as_hex();
print "hex $hex\n\n";

my $hex85 = Math::Base85::to_base85($hex);
print "hex85-> $hex85\n\n";

my $hex_back = Math::Base85::from_base85($hex85);
print "hex_back-> $hex_back\n";

my $bignum1 = Math::BigInt->new($hex_back);

my $b_back = $bignum1->as_bin();

#strip off the '0b1'
$b_back = substr($b_back, 3);
print "out-> $b_back\n";
print "in -> $str\n";

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