How to print one array of a multidimensional array in Perl?

#!usr/bin/perl
@array = ();
open(myfi开发者_运维知识库le,"sometext.txt");
while(<myfile>)
{
    chomp;
    push(@array,[split(" ")]);
}
close(myfile);
print @array[0];

Instead of printing the elements of the first array in this multidimensional array, it outputs the hexadecimal(?) pointer reference. If anyone knows how I can print this array, please post how and it will be greatly appreciated.

You should use strict and warnings. The latter would have told you the way to access the first row is $array[0]. Now, that value is a reference to the anonymous array you pushed on to @array. So, you need to dereference that: print "@{ $array[0] }\n";

#!/usr/bin/perl

use strict; use warnings;

my @array;

my $input_file = 'sometext.txt';

open my $input, '<', $input_file
    or die "Cannot open '$input_file': $!";

while(<$input>) {
    chomp;
    push @array, [ split ];
}

close $input;

print "@$_\n" for @array;

Perl doesn't do exactly what you want in this case. You need to explicitly tell Perl how to print out your array.

Try this:

use Data::Dumper;
print Dumper( $array[0] );

Or this:

foreach my $element ( @{ $array[0] } ) {
    print $element, "\n";
}

Or this:

print join ' ', @{ $array[0] };
print "\n";

Here's your example code, re-written a bit to do more error checking, and turn on strict and warnings. When these are turned on, Perl will do more checking and restrict you to a safer subset of the language.

#!/usr/bin/perl

use strict;
use warnings; 

my @arrays;
my $fn = 'summary.txt';
open FILE, "<$fn" or die "Error opening file ($!)";

while( my $line = <FILE> ) {
    chomp $line;
    my @data = split ' ', $line;
    push @arrays, \@data;
}
close FILE or die $!;

# print out comma-separated arrays, one per line
foreach my $array (@arrays) {
    print join ",", @$array;
    print "\n";
}

Here you go.

Perl's multi-dimensional arrays are really arrays of references to the arrays. In perl a reference is just a scalar variable. So, when you are trying to print your whole array it prints out just that reference. You need to use the @{} to change the context of the scalar to array.

#!/usr/bin/perl
@array = ();
open(myfile,"sometext.txt");
while(<myfile>)
{
    chomp;
    push(@array,[split(" ")]);
}
close(myfile);
print @{@array[0]};

I'm surprised that nobody mentioned this yet, but the standard way to print complex data is Data::Dumper.

use Data::Dumper;
#...
print Dumper( $array[0] );

You could also do:

print Dumper( @array );

Of course, you can't beat the ease of Smart::Comments, all you have to do is create comment using three initial hashes:

use Smart::Comments;
#...
### @array