Hello monks,
I have a question about perl syntax :
I know that this piece of code is the correct way to do what I need :

use strict;

my %hash = (
   'A' => 'on',
   'B' => 'on',
   'C' => 'off',
   'D' => 'off',
   'E' => 'off',
);

for (keys %hash) {
   my $result = (exists $hash{$_} and $hash{$_} eq 'on') 
      ? 'OK' 
      : 'KO';
   print $result, "\n";
}
[download]

but how comes the next piece of code ( which, in my opinion, would do the same thing ) doesn't work ? Could it be due to the exists function ( as suggested by a co-worker ) ? Here's the second piece of code :

use strict;

my %hash = (
   'A' => 'on',
   'B' => 'on',
   'C' => 'off',
   'D' => 'off',
   'E' => 'off',
);
for (keys %hash) {
   my $result;
   (exists $hash{$_} and $hash{$_} eq 'on') 
      ? $result = 'OK' 
      : $result = 'KO';
   print $result, "\n";
}
[download]

In the second sample, $result is assigned 'KO' everytime, and I just don't understand why.
Does anyone have a good explanation ?

Thanks for your answers