Storing an array in a hash

Question

So, this doesn't work, and I have no idea why. I've tried every possible variation. But nothing works. I'm ready to take a chainsaw to my server, but hopefully you can prevent that:

sub getQuestMarkers {
  #database stuff
  ...
  my %package;
  while(my ($key, $lat, $lng) = $sth->fetchrow_array()) {
    $package{$key} = ($lat,$lng);
  }

  ...
  return %package;
}

my %markers = getQuestMarkers();
while(my( $key, $value) = each %markers) {
  print "$key: @value - $value[0] $value[1]\n";
}

perldoc perlop: "Binary , is the comma operator. In scalar context it evaluates its left argument, throws that value away, then evaluates its right argument and returns that value. This is just like C's comma operator." — melpomene
– melpomene, Commented Apr 8, 2017 at 9:52
Always start with use strict; use warnings;. That would have told you that @value doesn't exist (it wasn't declared anywhere). — melpomene
– melpomene, Commented Apr 8, 2017 at 9:53

xxfelixxx · Accepted Answer · 2017-04-08 09:35:23Z

3

Use brackets [ ] to create an array reference, not parens ( );

As written, your code throws away the first value $lat. Write it like this instead:

$package{$key} = [$lat,$lng];

You can pull out the values like this:

my ($lat,$lng) = @{ $package{$key} };

In your code, you could print out the values by dereferencing them:

print "$key: " . $value->[0] . " " . $value->[1] . "\n";

Have a look at perldoc perlreftut.

edited Apr 8, 2017 at 9:35

answered Apr 8, 2017 at 9:29

xxfelixxx

6,6123 gold badges36 silver badges39 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Ratstail91 Over a year ago

Thank you so much! This has been frustrating me for days.

Collectives™ on Stack Overflow

Storing an array in a hash

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related