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Re(golf): I'm looking for the faster way to convert char 2 Bin and Bin 2 char (8bits)

by jynx (Priest)
on Jan 27, 2001 at 03:17 UTC ( [id://54673]=note: print w/replies, xml ) Need Help??


in reply to I'm looking for the faster way to convert char 2 Bin and Bin 2 char (8bits)

beware before!

Yesterday i found an amusing little routine to do decimal to binary (not the same drek everyone did in school as i understand it). So i converted it to perl and felt like posting it. Unfortunately i may have messed up something, so if someone (like maybe IO) could tell me if i did or not that would be sweet.

sub dec2bin {
   my $num = shift;
   my @num;  my $i = 0;

   (push @num, (($num & 2**$i) == 2**$i) ? 1 : 0) and $i++ until (2**$
+i > $num);
   return 0 + join '', reverse @num;
}

[download]
It is completely untested, but it should work (as if that's any boon to a programmer)

jynx

update: changed the $n to $num on line 5 according to IO's suggestion (thank you).

Replies are listed 'Best First'.
Re: Re(golf): I'm looking for the faster way to convert char 2 Bin and Bin 2 char (8bits)
by I0 (Priest) on Jan 27, 2001 at 05:08 UTC
    Testing it would have found
    Name "main::n" used only once: possible typo at - line 5.
    But besides that, ** is a more expensive operation than you need here especially doing it 3 times per iteration.
    using 1<<$iin place of 2**$i would be a bit faster.
      my $i = 1;
   (push @num, (($num & $i) ? 1 : 0)) and $i<<=1 until $i > $num;

    [download]
    is even better. And
    (push @num, (($num & 1) ? 1 : 0)) and $num>>=1 until 1 > $num;still faster...
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