Re: decimal - Binary
* Ronald J Kimball rjk-perl-...@tamias.net [2011-11-16 21:50]: It is greedy, but the important thing to remember is that the regular expression engine will find the longest *leftmost* match. To put that a third way: the engine will match at the first possible location, and will make the match as long as possible at that location.
Re: decimal - Binary
Greetings Sandro all,
From the keyboard of Sandro CAZZANIGA [16.11.11,14:26]:
hi!
Just a little JAPH for convert decimal to binary Feel free to comment
it ;)
golfed down a bit, just for fun...
#!/usr/bin/perl -l
@ARGV or die No args;
print$_: ,($_=unpackB*,packN,$_)=~s/0+//?$_:$_ for@ARGV;
#!/usr/bin/perl
use strict;
use warnings;
eval {@ARGV} or die(No args) ;
foreach my $arg(@ARGV) {
my $convert = unpack(B*,pack(N, $arg));
my @convertsp = split(, $convert);
my $count = 0;
foreach (@convertsp) {
unless ($convertsp[$count] == 1) {
$convertsp[$count] = ;
$count++;
}
}
print($arg: @convertsp \n);
}
exit 0;
cheers,
0--gg-
--
_($_= x(15).?\n.q·/)Oo. G°\/
/\_¯/(q/
\__(m.·.(_(always off the crowd)).·
);sub _{s./.($e='Itrs `mnsgdq Gdbj O`qkdq)=~y/-y/#-z/;$e.e print}
Re: decimal - Binary
What's the point? Seems to me the only purpose of this code beyond the obvious
unpack(B*,pack(N, $arg))
line is to reformat the result into an odd, probably application-dependent
format.
--- On Wed, 11/16/11, Sandro CAZZANIGA cazzaniga.san...@gmail.com wrote:
From: Sandro CAZZANIGA cazzaniga.san...@gmail.com
Subject: decimal - Binary
To: fwp@perl.org
Date: Wednesday, November 16, 2011, 8:26 AM
hi!
Just a little JAPH for convert decimal to binary Feel
free to comment
it ;)
#!/usr/bin/perl
use strict;
use warnings;
eval {@ARGV} or die(No args) ;
foreach my $arg(@ARGV) {
my $convert = unpack(B*,pack(N, $arg));
my @convertsp = split(, $convert);
my $count = 0;
foreach (@convertsp) {
unless ($convertsp[$count] ==
1) {
$convertsp[$count] = ;
$count++;
}
}
print($arg: @convertsp \n);
}
exit 0;
Re: decimal - Binary
On 2011-11-16 09:57 -0500, Ronald J Kimball wrote: That should be s/0*//, otherwise you'll get the wrong result for numbers above 2147483647. That should be s/^0*//, otherwise you'll get the wrong result for numbers above 2147483647. Also: printf$_:%b\n,$_ for@ARGV -- --- | Olof Johansson http://stdlib.se/ | ---
Re: decimal - Binary
On Wed, Nov 16, 2011 at 04:14:57PM +0100, Olof Johansson wrote: On 2011-11-16 09:57 -0500, Ronald J Kimball wrote: That should be s/0*//, otherwise you'll get the wrong result for numbers above 2147483647. That should be s/^0*//, otherwise you'll get the wrong result for numbers above 2147483647. No, you are wrong. s/0*// is sufficient, because /0*/ will always match at the start of the string anyway. Ronald
Re: decimal - Binary
Hasn't anyone noticed that a decimal to binary or whatever conversion
isn't a JAPH by definition, alone because it does anything other than
output the JAPH? With a looser definition it must at least output Just
another Perl hacker, perhaps on stderr
Daniel Cutter
@_=($_=aaceeehhjklnoprrrsttu, q)411!**.#)(#'$);for$a(map{
'.'x(ord($_)-3*11)}$_[1]=~m,.,g){s,($a)(.),$1,,$b.=$2};$c.=(.{$_})
for(4,7,4,6);@_=$b=~m,$c,;push@_,\n;print map{ucfirst}map{$_.$}@_
Am 16.11.2011 17:57, schrieb Ronald J Kimball:
On Wed, Nov 16, 2011 at 04:14:57PM +0100, Olof Johansson wrote:
On 2011-11-16 09:57 -0500, Ronald J Kimball wrote:
That should be s/0*//, otherwise you'll get the wrong result for numbers
above 2147483647.
That should be s/^0*//, otherwise you'll get the wrong result for
numbers above 2147483647.
No, you are wrong. s/0*// is sufficient, because /0*/ will always match at
the start of the string anyway.
Ronald
Re: decimal - Binary
On 2011-11-16 11:57 -0500, Ronald J Kimball wrote: No, you are wrong. s/0*// is sufficient, because /0*/ will always match at the start of the string anyway. You're clearly an expert. I yield. Can you open a bug report with perl and getting this fixed? -- --- | Olof Johansson http://stdlib.se/ | ---
Re: decimal - Binary
On Wed, Nov 16, 2011 at 07:49:14PM +0100, Olof Johansson wrote: On 2011-11-16 11:57 -0500, Ronald J Kimball wrote: No, you are wrong. s/0*// is sufficient, because /0*/ will always match at the start of the string anyway. You're clearly an expert. I yield. Can you open a bug report with perl and getting this fixed? It's working as expected for me, so I'm not sure what needs to be fixed. % cat tmp.pl #!perl -l print$_: ,($_=unpackB*,packN,$_)=~s/0*//?$_:$_ for@_=@ARGV; print$_: ,($_=unpackB*,packN,$_)=~s/^0*//?$_:$_ for@_=@ARGV; % perl tmp.pl 2147483648 30 2147483648: 1000 30: 1011001011010100 2147483648: 1000 30: 1011001011010100 % Are you seeing different behavior? Ronald
Re: decimal - Binary
From the keyboard of Ronald J Kimball [16.11.11,14:14]:
On Wed, Nov 16, 2011 at 07:49:14PM +0100, Olof Johansson wrote:
On 2011-11-16 11:57 -0500, Ronald J Kimball wrote:
No, you are wrong. s/0*// is sufficient, because /0*/ will always match at
the start of the string anyway.
rye
You're clearly an expert. I yield. Can you open a bug report with perl
and getting this fixed?
It's working as expected for me, so I'm not sure what needs to be fixed.
well... the ternary ?: isn't necessary with s/0*// because s/0*// is
always successful, so
print$_: ,($_=unpackB*,packN,$_)=~s/0*//$_ for@ARGV;
two strokes ;-)
but as Olof pointed out,
printf$_:%b\n,$_ for@ARGV
is less convoluted. Why do I forget about printf almost always?
'cause I'm not a C hacker, but a heck parler, I guess ;-)
for some JAPH, see my signature. Latin-1 only, though
cheers,
0--gg-
% cat tmp.pl
#!perl -l
print$_: ,($_=unpackB*,packN,$_)=~s/0*//?$_:$_ for@_=@ARGV;
print$_: ,($_=unpackB*,packN,$_)=~s/^0*//?$_:$_ for@_=@ARGV;
% perl tmp.pl 2147483648 30
2147483648: 1000
30: 1011001011010100
2147483648: 1000
30: 1011001011010100
%
Are you seeing different behavior?
Ronald
--
_($_= x(15).?\n.q·/)Oo. G°\/
/\_¯/(q/
\__(m.·.(_(always off the crowd)).·
);sub _{s./.($e='Itrs `mnsgdq Gdbj O`qkdq)=~y/-y/#-z/;$e.e print}
Re: decimal - Binary
On 2011-11-16 14:14 -0500, Ronald J Kimball wrote: It's working as expected for me, so I'm not sure what needs to be fixed. Hum, now I'm ashamed. Sorry. But why is that not greedy? (I got other results earlier, but I can't reproduce now so I have probably made an error in my earlier attempts.) -- --- | Olof Johansson http://stdlib.se/ | ---
Re: decimal - Binary
Olof Johansson o...@ethup.se wrote: But why is that not greedy? Remember, the *first* match wins, even if it's shorter than a possible later match. ISTR that some have argued that's a bug. Well, too bad. It's too late. :-) -- john many jars porter
Re: decimal - Binary
On Wed, Nov 16, 2011 at 09:34:58PM +0100, Olof Johansson wrote: On 2011-11-16 14:14 -0500, Ronald J Kimball wrote: It's working as expected for me, so I'm not sure what needs to be fixed. Hum, now I'm ashamed. Sorry. But why is that not greedy? (I got other results earlier, but I can't reproduce now so I have probably made an error in my earlier attempts.) It is greedy, but the important thing to remember is that the regular expression engine will find the longest *leftmost* match. For example, 00111000 =~ /0*/ will match (00)111000. It won't match (0)0111000, because, although it's a leftmost match, it's not the longest leftmost match. And it won't match 00111(000) because that's not a leftmost match, regardless of the length. Ronald
