Monks, I was attempting to answer the Cartalk Puzzler when I came across something else that puzzled me.

I expect the following code to behave the same whether using "normal" if or "ternary" ? : ; style if. But, I get different results. Can someone explain this? 

use strict;
use warnings;
use Data::Dumper;

my %lights;

$lights{$_} = 0 for (1..4);
foreach my $light ( sort { $a <=> $b } (keys %lights) ){
        foreach my $divisor ( 2..4 ) {
            if ( $light % $divisor == 0 ) { # if it divides evenly, pu
+ll the cord
                if ( $lights{$light} ) {
                    $lights{$light} = 0;
                } else {
                    $lights{$light} = 1;
                } 
            }
        }
}
report({%lights}); # outputs 1 4

$lights{$_} = 0 for (1..4);
foreach my $light ( sort { $a <=> $b } (keys %lights) ){
        foreach my $divisor ( 2..4 ) {
            if ( $light % $divisor == 0 ) { # if it divides evenly, pu
+ll the cord
                $lights{$light} ? $lights{$light} = 0 : $lights{$light
+} = 1; # turn off if it's on, and vice versa.
            }
        }
}
report({%lights}); #outputs 1


sub report {
    my $lights = shift;
    print "off lights: ";
    foreach (sort { $a <=> $b }( keys %{$lights} ) ) {
            print "$_ " unless $lights->{$_}; 
    }
    print "\n";
}

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In reply to Ternary if versus normal if question by tphyahoo

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