copying array of hashes

Posted on 2009-05-10
Last Modified: 2012-05-06
how can I make a copy of an array of hashes so that the original one isn't affected? I don't have use storage in my PERL version
Question by:cucugirl
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 84

Accepted Solution

ozo earned 84 total points
ID: 24349370
print "$copy[1]{k2} $array[1]{k2}\n";
LVL 39

Expert Comment

ID: 24351547
>>I don't have use storage
I'm assuming you meant you don't have the Storable module?  If so, can you install it?  Have you tried?  Did you get an error?

Assisted Solution

vikaskhoria earned 83 total points
ID: 24352113
Check my script below:
(This deletes elements from the hash and the original hash is modified to the desired hash)


my %my_hash = ('TEST' =>'T' ,'QUIZ'=>'4','HWORK'=>'3');
my @table = ( {'TEST'=>'T'}, {'TEST'=>'F'},{'QUIZ'=>'1'},{'QUIZ'=> '2'},{'HWORK'=>'3'}, {'HWORK'=>'3'});
for my $value (keys %my_hash)
        my $found = 0;
        foreach $i (0 .. @table-1)
                if ( $table[$i]{$value} == $my_hash{$value} ) {
                        $found = 1;
        if ( ! $found )

Open in new window


Expert Comment

ID: 24361590
Check this link below:

This talks about copying array of hashes.
This may be of some help to you.
LVL 26

Assisted Solution

wilcoxon earned 83 total points
ID: 25953183
The best way is to use Clone (this handles any level of nested structures).  Alternately, if you know that the hashes only contain scalars, it's easy to copy them manually.
my $orig = [{first=>1,second=>2},{first=>3,second=>4}]; 
# using Clone
use Clone qw(clone);
my $copy = clone($orig); 
# manually copying
## slow/inefficient way
my $copy = [];
foreach my $el (@$orig) {
    my %tmp;
    foreach my $key (%$el) {
        $tmp{$key} = $el->{$key};
    push @$copy, {%tmp};
## better way
my $copy = [];
foreach my $el (@$orig) {
    push @$copy, {%$el};
## ozo's way - more succinct but should be about same performance (I think)
my $copy = [map { {%$_} } @$orig];

Open in new window


Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
pattern matching in perl 2 111
perl to convert excel to csv 3 310
use google analytics code in perl script 2 92
Perl Untar File 1 70
On Microsoft Windows, if  when you click or type the name of a .pl file, you get an error "is not recognized as an internal or external command, operable program or batch file", then this means you do not have the .pl file extension associated with …
Email validation in proper way is  very important validation required in any web pages. This code is self explainable except that Regular Expression which I used for pattern matching. I originally published as a thread on my website : http://www…
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…

696 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question