bebe has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks, could you please get some help with the code below. It works but I think I'm doing this conversions very inefficiently, I was wondering if you have other suggestions or better alternatives I could use. I appreciate it all. :-) 


# rand1 is array of binaries
# basically, I want to convert array of binaries to hex string

 my $bin = arraystring (@rand1);
 my $dec = stringdecimal($bin);
 my $hex = sprintf("0x%x", $dec);
 

  sub stringdecimal {
    return unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
  }

  sub arraystring {
     my $string = join('', @_);
     return $string;
  }

[download]

Replies are listed 'Best First'.
Re: array of binaries to hex conversion
by jwkrahn (Abbot) on Sep 11, 2012 at 05:49 UTC 
    $ perl -le'
my @rand1 = qw( 0 1 0 1 0 1 0 1 0 1 1 1 0 1 1 0 0 0 1 );

sub stringdecimal {
    return unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
    }

sub arraystring {
    my $string = join("", @_);
    return $string;
    }

my $bin = arraystring (@rand1);
my $dec = stringdecimal($bin);
my $hex = sprintf("0x%x", $dec);

print $hex;
'
0x2abb1

$ perl -le'
my @rand1 = qw( 0 1 0 1 0 1 0 1 0 1 1 1 0 1 1 0 0 0 1 );

my $hex = sprintf "0x%x", oct "0b" . join "", @rand1;

print $hex;
'
0x2abb1

    [download]
[reply]
[d/l]

      Perfect!! thanks a lot!!!!

[reply]

      Hello jwkrahn

      I have just read perlpacktut and I would like to have some clue for my 2 questions about this thread.

      What OP does is in short... 

      printf "0x%x\n",                #print it as hex
    unpack("N",                 #unpack it as 32bit int ,big endian
        pack("B32",             #pack it as MSB 32bit integer
            sprintf("%032s",    #32 length bit string
                join('',
                    @rand1))));

      [download]
      1. Does it really MSB ?

      MSB should pad '0' for right side, not left side, doesn't it ? 
      my @rand1 = qw( 1 );
      this currenty goes "00000000000000000000000000000001". Is it OK?

      2. How oct insures it is MSB and 32bit big endian?

      Does oct thinks it as 'long long' seeing the size of $Config{longlongsize}? How it thinks for MSB? 
      use Config;
print "int size=".$Config{intsize}."\n";
print "short size=".$Config{shortsize}."\n";
print "long size=".$Config{longsize}."\n";
print "long long size=".$Config{longlongsize}."\n";

      [download]
      If I could have some explanations by you or other monks, I am glad.

[reply]
[d/l]
[select]
[reply]
Re: array of binaries to hex conversion
by Anonymous Monk on Sep 11, 2012 at 07:02 UTC 
    #!/usr/bin/perl --
use strict; use warnings; use Data::Dump;
my @rand1 = qw( 0 1 0 1 0 1 0 1 0 1 1 1 0 1 1 0 0 0 1 );
my $bin = arraystring (@rand1);
my $dec = stringdecimal($bin);
my $hex = sprintf("0x%x", $dec);
my $ex = b32hex(@rand1);

dd \@rand1, $bin, $dec, $hex, $ex;


sub stringdecimal {
return unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
}

sub arraystring {
 my $string = join('', @_);
 return $string;
}

sub b32hex {
    '0x'. unpack 'H*', pack("B32", substr("0" x 32 . join('',@_), -32)
+)
}
__END__
(
  [0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 1],
  "0101010101110110001",
  175025,
  "0x2abb1",
  "0x0002abb1",
)

    [download]
[reply]
[d/l]

      Hello.

      I would like to ask you a question. The result will differ by byte orders. 

      my $tmp=pack("B32", substr("0" x 32 . join('',@rand1), -32));

#this prints 'as 32bit big endian:0x2abb1'
printf "as 32bit big endian:0x%x\n", unpack('N',$tmp) ;

#this prints 'as 32bit little endian:0x200'
printf "as 32bit little endian:0x%x\n", unpack('S',$tmp) ;

      [download]
      There is "<" for little endian, and ">" for big endian, which pack,unpack offers. OP treats it as "N"=32bit int, big endian, so I would like to do like this. 
      pack("B>32", $bitstring);
pack("(B32)>*",$bitstring);
      But both of them doesn't work...
      How can I add endian specification with your one line conversion? Is there a good way?

[reply]
[d/l]

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