Re: Dangerous Names

Perl wants to see numbers around <=> (spaceship) operator and converts strings to numbers. ~~"Nan" and "NaN" are both converted to zero~~.

Update: Strings which start with "nan" (/^nan/i) are converted to nan, others which start with "inf" (/^inf/i) converted to inf. Others are converted to zero unless begin with digits.

see perldoc peldata (Scalar values)

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

my @s =qw(nan naNo inf InfInity infimum foo bar 123dd);
print "$_ => ", $_+0 for @s;

__END__

Argument "naNo" isn't numeric in addition (+) at a.pl line 7.
Argument "infimum" isn't numeric in addition (+) at a.pl line 7.
Argument "foo" isn't numeric in addition (+) at a.pl line 7.
Argument "bar" isn't numeric in addition (+) at a.pl line 7.
Argument "123dd" isn't numeric in addition (+) at a.pl line 7.
nan => nan
naNo => nan
inf => inf
InfInity => inf
infimum => inf
foo => 0
bar => 0
123dd => 123
[download]

Comment on Re: Dangerous Names Select or Download Code

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Re^2: Dangerous Names by samtregar (Abbot) on Dec 17, 2008 at 21:58 UTC
Incorrect! Proof: `$ perl -e '@names = (["Nan Tregar"], ["Sam Tregar"]); @names = sort { +$a->[0] <=> $b->[0] } @names;' Sort subroutine didn't return a numeric value at -e line 1.` [download] Note that you have to work a little. Just a straight { $a <=> $b } gets optimized into something that doesn't do the NaN conversion. -sam	[reply] [d/l]
Re^3: Dangerous Names by ikegami (Patriarch) on Dec 17, 2008 at 22:04 UTC
I didn't need to do any extra work. See my post below. `$ perl -v This is perl, v5.8.8 built for x86_64-linux-gnu-thread-multi` [download]	[reply] [d/l]
Re^4: Dangerous Names by samtregar (Abbot) on Dec 17, 2008 at 22:05 UTC
Ok - but do you find it unusual that sort { $a <=> $b } doesn't die, but sort { $a->[0] <=> $b->[0] } does? -sam	[reply]
Re^5: Dangerous Names by ikegami (Patriarch) on Dec 17, 2008 at 22:09 UTC
Re^6: Dangerous Names by samtregar (Abbot) on Dec 17, 2008 at 22:13 UTC
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