Discussion of Perl's three built-in data types: scalars, arrays of scalars, and associative arrays of scalars, known as "hashes". At your command-line: perldoc perldata
Questions tagged [perl-data-structures]
401 questions
120
votes
2 answers
How do I enter a multi-line comment in Perl?
Possible Duplicate:
What are the common workarounds for multi-line comments in Perl?
How do I add a multi-line comment to Perl source code?
vrbilgi
- 5,163
- 11
- 38
- 56
47
votes
6 answers
Perl array vs list
I have two data structures in Perl:
An array:
my @array2 = ( "1", "2", "3");
for $elem (@array2) {
print $elem."\n";
}
Giving me the following output:
1
2
3
And a list:
my @array = [ "1", "2", "3"]; …
Marcin Cylke
- 2,022
- 2
- 21
- 38
30
votes
2 answers
How does double arrow (=>) operator work in Perl?
I know about the hash use of the => operator, like this
$ cat array.pl
%ages = ('Martin' => 28,
'Sharon' => 35,
'Rikke' => 29,);
print "Rikke is $ages{Rikke} years old\n";
$ perl array.pl
Rikke is 29 years old
$
and I thought it…
Lazer
- 79,569
- 109
- 264
- 349
24
votes
5 answers
How can I store multiple values in a Perl hash table?
Up until recently, I've been storing multiple values into different hashes with the same keys as follows:
%boss = (
"Allan" => "George",
"Bob" => "George",
"George" => "lisa" );
%status = (
"Allan" => "Contractor",
"Bob" …
paxdiablo
- 772,407
- 210
- 1,477
- 1,841
22
votes
7 answers
How can I maintain the order of keys I add to a Perl hash?
How can I maintain the order of actual list after counting its occurrence using a hash in the following program? For example, are
a
b
e
a
c
d
a
c
d
b
etc.
Using hash, i counted the occurrence of each element.
and what i want is:
a 3
b …
Cthar
- 623
- 2
- 8
- 11
18
votes
4 answers
What are anonymous hashes in perl?
$hash = { 'Man' => 'Bill',
'Woman' => 'Mary,
'Dog' => 'Ben'
};
What exactly do Perl's “anonymous hashes” do?
user1363308
- 908
- 3
- 12
- 32
17
votes
9 answers
How to iterate through Hash (of Hashes) in Perl?
I have Hash where values of keys are other Hashes.
Example: {'key' => {'key2' => {'key3' => 'value'}}}
How can I iterate through this structure?
Jay Gridley
- 683
- 2
- 12
- 31
14
votes
6 answers
How to get hashes out of arrays in Perl?
I want to write a little "DBQuery" function in perl so I can have one-liners which send an SQL statement and receive back and an array of hashes, i.e. a recordset. However, I'm running into an issue with Perl syntax (and probably some odd…
Edward Tanguay
- 176,854
- 291
- 683
- 1,015
14
votes
5 answers
How do I retrieve an integer's ordinal suffix in Perl (like st, nd, rd, th)
I have number and need to add the suffix: 'st', 'nd', 'rd', 'th'. So for example: if the number is 42 the suffix is 'nd' , 521 is 'st' and 113 is 'th' and so on.
I need to do this in perl. Any pointers.
bozo user
- 231
- 1
- 4
- 14
13
votes
1 answer
How do I create a 2D array in Perl?
I am trying to create a 2d array in Perl
my code:
my @wordsList=();
my @words=();
for ($id=0; $id<=@language.length; $id++)
{
my $eng = $db->selectall_arrayref("select word from words
…
JoT
- 303
- 1
- 3
- 10
11
votes
2 answers
In Perl, why does concatenating a hash with a string give a fraction-looking result?
I have the following hash:
my %villains = {
"Boba" => "Fett",
"Darth" => "Vader",
"Moff" => "Tarkin",
}
I then print it like so:
print "".%villains;
I get the following output:
1/8
What semantics in Perl make this happen?
Thank you!
Dmitry Blotsky
- 193
- 7
10
votes
7 answers
Is there a way to replace an if-elsif-else in Perl with something better?
I want to build a bunch of Perl subrotines that all have the same template if elsif elsif else that takes a decision based on a factor variable. Here's an example of subroutine template:
sub get_age{
my $factor=shift;
if ($factor == 1 ){…
smith
- 3,045
- 24
- 51
10
votes
1 answer
How do I access a value of a nested Perl hash?
I am new to Perl and I have a problem that's very simple but I cannot find the answer when consulting my Perl book.
When printing the result of
Dumper($request);
I get the following result:
$VAR1 = bless( {
'_protocol' => 'HTTP/1.1',
…
st.
- 156
- 1
- 6
9
votes
1 answer
Why no interpolation within `map` BLOCK?
This throws an error in Perl v5.20:
use strict;
use warnings;
my @a = (2,3,9);
my %b = map { "number $_" => 2*$_ } @a;
Error:
syntax error at a.pl line 4, near "} @a"
Execution of a.pl aborted due to compilation errors.
This doesn't:
use…
user1427008
8
votes
2 answers
Search for hash in an array by value
I have a function which extracts Excel data into an array of hashes like so:
sub set_exceldata {
my $excel_file_or = '.\Excel\ORDERS.csv';
if (-e $excel_file_or) {
open (EXCEL_OR, $excel_file_or) || die("\n can't open…
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