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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 ( #54673=note: print w/replies, xml ) Need Help??

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

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