I agree with GrandFather that changing $ref (a reference to an anonymous hash) to %hash (an ordinary hash) is the better approach here. But, for completeness, I will point out that the original design can be made to work by changing the line print "@{$ref{$k}} \n; to print "@{$ref->{$k}} \n"; — that is, by adding in the dereferencing operator ->. See perlreftut.

However, my major concern is with the regular expressions. As written, the first expression $k =~ /US/ will match the character sequence “US” anywhere in the string. It is always a good idea to prevent unwanted matches by limiting, as much as possible, the conditions under which the regex can match. For example:

if (($k =~ /^US/) && ($k =~ m{/$loc})) {
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might be a useful step in this direction. It matches “US” only at the beginning of the string, and “Lynnwood”, “Edmonds”, etc. only when they follow a forward slash.

Hope that helps,

It's conventional and helpful for you to describe the error or problem. In this case it's evident enough, especially as leaping straight into using a hash reference instead of a hash is something of a code smell.

Change my $ref = { to my %hash = ( (and change the closing '}' of course). Remove @keys and change my $k(@keys) to my $k (keys %hash).

Thanks guys, I updated the existing code, its working now. Culprit was, I was using $ref{$k} instead of $ref->{$k} So dumb :-)

Please do not just change your OP without indicating (in your OP) what you've changed.

How to handle this situation is described in "How do I change/delete my post?" (which explains why as well as how).

Update: While I indicated "OP" above (as that was applicable to this specific case), the information about changing the content of your post applies to any node you write.

-- Ken

Culprit was, I was using $ref{$k} instead of $ref->{$k}

Nope. Unless there is more context than you are telling us, the culprit is using a hash reference instead of a hash.

References are fine where they are needed, but require needless extra syntax where a simple variable will suffice.

True laziness is hard work

G'day sunil9009,

Another issue you have here is that you're checking all the keys for a match with the first element of @ValidLocations, then checking all the keys again for a match with the next element of @ValidLocations. This means you're performing a lot of unnecessary processing: assuming the data you've posted is just a sample of the real dataset, this could be a substantial amount of unnecessary processing.

Consider coding your solution more like this:

#!/usr/bin/env perl -l

use strict;
use warnings;

my @ValidLocations = ('Lynnwood','Edmonds');
my $ref = {
    'US/Seattle/WA' => ['Smith','Eric','Sam'],
    'US/WA/Lynnwood' => ['John','Chuck','Ram','Lynda'],
    'US/WA/Everette' => ['Sun','Rick','Raj'],
    'US/Edmonds/WA' => ['Ken','Josh','Matt'],
    'IN/Banglore/KA' => ['Anil','Dada','Kaka']
};

my $re = '^US.+?(?:' . join('|' => @ValidLocations) . ')';
my @valid_us_people = map { @{$ref->{$_}} } grep { /$re/ } keys %$ref;
print "@valid_us_people";
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Output:

John Chuck Ram Lynda Ken Josh Matt
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You may already have your data as a hashref. If not, and you choose to change $ref to %hash (as suggested by GrandFather in the first reply), just change $ref->{$_} to $hash{$_} and %$ref to %hash.