Absolutely!

--hsm

"Never try to teach a pig to sing...it wastes your time and it annoys the pig."

Note that "exponential" is also called "winkie", due to The Wizard of Oz.

The dog named Zero from the book _Ordinary Jack_ is the one true dog named Zero.

Tha kamikaze who survives the mission is one true zero.

Zero is nothing, so undef is the true zero!

(If only undef didn't give warnings in arithmetic...)

A lot of people don't seem to understand the poll... or I'm not getting their jokes, which is also possible.

Anyway, there is sometimes a wish for something that is considered zero when used in numeric context, but true when used in boolean context, that is something that will make the following print "42\n":

#!/usr/bin/perl
use warnings;
use strict;

my $x='<some choice on the poll>';
print $x+42, "\n" if ($x);
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Aha the naughty nought. I wonder how many others have been bitten by this with DBI return codes.

Are any of the other true zero values used I wonder?

Couldn't vote! The one true anything is just dogma.

print scalar reverse 'dogma';
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Number of times I have been right, according to my wife.

'Wife'? Then she must admit you've been right at least once... ;)

Her version is she picked me....

g_White

There may be many ways to skin a cat, but only an escaped lunatic would actually try them out in practice. (-S)

Couldn't vote! The one true zero is just 0. No plusses, dashes, letters, spaces or any other superfluous fluff :)

update: yes, I am aware of the zero, true zero dichotomy which is what the poll is about. Let me just say... "truth wears many faces"

That's like saying that all primes are odd except 2 which is the oddest amongst all.

The one true zero is just 0. No plusses, dashes, letters, spaces or any other superfluous fluff.

Ah, but this poll isn't about the one true "zero" but about the best "true zero" — of the various values in Perl which are zero in numeric context but true in boolean context, which do you like best?

Just "0" fails cos it's false, not true; you need some of that "superfluous fluff" to make it a "true zero".

Smylers

Isn't 0E0 and "Larry's 0 but true" the same? :-)

Not at all. "0 but true" describes a state of data in Perl. "0E0" is part of the lyrics for the background singers in "Jungle Love" by Morris Day and the Time. Quite different.

--
tbone1, YAPS (Yet Another Perl Schlub)
And remember, if he succeeds, so what.
- Chick McGee

No, it's really the string "0 but true". Try this for example:

use File::Temp; $th = File::Temp::tempfile(undef, "UNLINK", 1); $zbt =
+ sysseek $th, 0, 0; print $zbt, "\n";
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The "E0" suffix appears with the flip-flop operators, but "0E0" can never appear, only "1E0", "2E0" etc.

true, but also not true :-)

Many functions -like the execute function in DBI- return 0E0 when they want to return a result that is ment to be zero but is 'boolean' true in tests

So, indeed it is not general perl, but it is common to use 0E0 as "zero but true".

Cheers,


---------------------------
Dr. Mark Ceulemans
Senior Consultant
BMC, Belgium

No.

$ perl -wle'print "0 but true" eq "0E0" ?1:0'
0
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They are both silently equal to zero yet true, but so are the other poll options (except "0x0").

$ perl -wle'print 0+"0 but true"'
0

$ perl -wle'print 0+"0E0"'
0

$ perl -wle'print "0 but true" ?"true":"false"'
true

$ perl -wle'print "0E0" ?"true":"false"'
true
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Hector Zeroni from Holes...or Zero in Beetle Bailey...

Other: Zero from the Megaman X series. ;)

There is a difference. For example, DBI's do() returns the number of rows affected -- but some statements succeed even though no rows were affected. This allows for the following bit of code to be sane:

my $rows = $dbh->do(
   'UPDATE MyTable SET note_date = GETDATE() 
    WHERE ErrorCode IS NOT NULL'
);

if ($rows) {
   # true, even if zero rows were affected.
   print 'Found and updated rows: (',$rows,")\n";
}
else {
   warn 'Error during update query';
}
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Having a query affect zero rows is perfectly valid, and doesn't necessarily mean an error. This makes even more sense when other methods in the same program return '0' as the false value rather than undef: it allows for programmer choice and a consistent read.

Larry Wall is Yoda: there is no try{}
The Code that can be seen is not the true Code

Kelvin might have an absolute for you.

Kelvin is Lord!

The one true zero is of course $foo % $foo.

Zapato is totally whacked....

Paulster2


You're so sly, but so am I. - Quote from the movie Manhunter.

The thing I like about "0 but true" is that it is self-explanatory; with any of the others, I'd feel obligated to insert a comment explaining why I was returning zero in that particular way, so that some hapless soul a few years later doesn't pull out hair figuring out why my code is so weird; with "0 but true" I expect any decent Perl programmer to be able to figure it out, because the jist of the reason is contained in the value; assuming the reader understands context, it'll just click. (And if the reader doesn't understand context, he won't be able to maintain my code anyway; I make frequent use of context and consider it a major concept of the language.)

use Scalar::Util qw(dualvar);
my $true_zero = dualvar(0,"my true zero is better than yours");
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$ perl -wle'print 0+"0x0"'
Argument "0x0" isn't numeric in addition (+) at -e line 1.
0
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Behaviour change or bad poll option?

Update: 5.3 warned.

The one true zero is