Pathologically Eclectic Rubbish Lister PerlMonks

### Re: Re: Re: Hash slices ?

by davorg (Chancellor)
 on Dec 01, 2000 at 17:53 UTC ( #44343=note: print w/replies, xml ) Need Help??

in reply to Re: Re: Hash slices ?

Any one further investigation, it seems that my original solution suffered from a fundamental problem.

```my %hash = (one => 1, two => 2, three => 3);
my @keys = qw(four five six);
my @slice = @hash{@keys};

@slice is now contains four undef elements, where I thought it would be an empty list (don't know why I thought that - it was very early in the morning.

If the hash slice was interpreted as an array, it would therefore always be true and therefore doesn't solve ChOas' original problem. That would be better addressed using something like:

```if (grep { exists %hash{\$_} } @keys) {
print "yep\n";
} else {
print "nope\n";
}
--
<http://www.dave.org.uk>

"Perl makes the fun jobs fun
and the boring jobs bearable" - me

Replies are listed 'Best First'.
Re: Re: Re: Re: Hash slices ?
by snax (Friar) on Dec 01, 2000 at 18:03 UTC
```perl -w -e '%x=(a=>7,b=>8,c=>9);@s=(qq(a),qq(b));\$y=@x{@s};print \$y;'
returns 8 -- so it is pretty clearly the case that a hash slice is properly a list.

Re: Re: Re: Re: Hash slices ?
by ChOas (Curate) on Dec 01, 2000 at 18:09 UTC
I was thinking about doing it like this to avoid the grep:
```   sub Match{foreach (@keys) {return 1 if exists \$hash{\$_};}return 0}
if ( Match  )
{
print "yep\n";
} else {
print "nope\n";
};
the slice ;))

Create A New User
Node Status?
node history
Node Type: note [id://44343]
help
Chatterbox?
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others avoiding work at the Monastery: (13)
As of 2017-07-20 13:02 GMT
Sections?
Information?
Find Nodes?
Leftovers?
Voting Booth?
I came, I saw, I ...

Results (301 votes). Check out past polls.