Easy way to print Perl array? (with a little formatting)

Question

Is there an easy way to print out a Perl array with commas in between each element?

Writing a for loop to do it is pretty easy but not quite elegant....if that makes sense.

Answer 1

Just use join():

# assuming @array is your array:
print join(", ", @array);

Answer 2

You can use Data::Dump:

use Data::Dump qw(dump);
my @a = (1, [2, 3], {4 => 5});
dump(@a);

Produces:

"(1, [2, 3], { 4 => 5 })"

Answer 3

If you're coding for the kind of clarity that would be understood by someone who is just starting out with Perl, the traditional this construct says what it means, with a high degree of clarity and legibility:

$string = join ', ', @array;
print "$string\n";

This construct is documented in perldoc -fjoin.

However, I've always liked how simple $, makes it. The special variable $" is for interpolation, and the special variable $, is for lists. Combine either one with dynamic scope-constraining 'local' to avoid having ripple effects throughout the script:

use 5.012_002;
use strict;
use warnings;

my @array = qw/ 1 2 3 4 5 /;

{
    local $" = ', ';
    print "@array\n"; # Interpolation.
}

OR with $,:

use feature q(say);
use strict;
use warnings;

my @array = qw/ 1 2 3 4 5 /;
{
    local $, = ', ';
    say @array; # List
}

The special variables $, and $" are documented in perlvar. The local keyword, and how it can be used to constrain the effects of altering a global punctuation variable's value is probably best described in perlsub.

Enjoy!

Answer 4

Also, you may want to try Data::Dumper. Example:

use Data::Dumper;

# simple procedural interface
print Dumper($foo, $bar);

Answer 5

For inspection/debugging check the Data::Printer module. It is meant to do one thing and one thing only:

display Perl variables and objects on screen, properly formatted (to be inspected by a human)

Example usage:

use Data::Printer;  
p @array;  # no need to pass references

The code above might output something like this (with colors!):

   [
       [0] "a",
       [1] "b",
       [2] undef,
       [3] "c",
   ]

Answer 6

You can simply print it.

@a = qw(abc def hij);

print "@a";

You will got:

abc def hij

Answer 7

# better than Dumper --you're ready for the WWW....

use JSON::XS;
print encode_json \@some_array

Answer 8

Using Data::Dumper :

use strict;
use Data::Dumper;

my $GRANTstr = 'SELECT, INSERT, UPDATE, DELETE, LOCK TABLES, EXECUTE, TRIGGER';
$GRANTstr    =~ s/, /,/g;
my @GRANTs   = split /,/ , $GRANTstr;

print Dumper(@GRANTs) . "===\n\n";

print Dumper(\@GRANTs) . "===\n\n";

print Data::Dumper->Dump([\@GRANTs], [qw(GRANTs)]);

Generates three different output styles:

$VAR1 = 'SELECT';
$VAR2 = 'INSERT';
$VAR3 = 'UPDATE';
$VAR4 = 'DELETE';
$VAR5 = 'LOCK TABLES';
$VAR6 = 'EXECUTE';
$VAR7 = 'TRIGGER';
===

$VAR1 = [
          'SELECT',
          'INSERT',
          'UPDATE',
          'DELETE',
          'LOCK TABLES',
          'EXECUTE',
          'TRIGGER'
        ];
===

$GRANTs = [
            'SELECT',
            'INSERT',
            'UPDATE',
            'DELETE',
            'LOCK TABLES',
            'EXECUTE',
            'TRIGGER'
          ];

Answer 9

This might not be what you're looking for, but here's something I did for an assignment:

$" = ", ";
print "@ArrayName\n";

Answer 10

Map can also be used, but sometimes hard to read when you have lots of things going on.

map{ print "element $_\n" }   @array; 

Answer 11

I've not tried to run below, though. I think this's a tricky way.

map{print $_;} @array;