Perl：数组引用的数组

Question

Might be repeated somewhere but i've looked at every perl array referencing / dereferencing example i've been able to find and tried running 10+ different combos of this string to get my desired output. Such as @$array[i], @{$array[i]}, @{@$array[i]} etc.

So I have an array of array references. I built this by creating a global array, and then I push smaller temp arrays into that global array. The final outcome looks something like this when Dumper() is ran.

$VAR1 = [ 1 ]; $VAR2 = []; $VAR3 = []; $VAR4 = []; $VAR5 = []; $VAR6 = []; $VAR7 = [ 1 ]; $VAR8 = []; $VAR9 = []; $VAR10 = []; $VAR11 = [ 1 ]; $VAR12 = []; $VAR13 = [ 1 ]; $VAR14 = []; $VAR15 = [ 1 ];

Now I am trying to dereference one of these arrays by using

my @arrayRef = @{$redArray[$i]};
print "Here: " . @arrayRef[0];

@redArray is my global array.

The @{$redArray[$i]} part I see as get the reference from the global array, and then deference it which should return as array like [] or [1] or [1,1 .....]

Then on line two I want to get the first element of the array, which would return nothing/error or 1.

When print "Here: " . @arrayRef[0]; runs though, the output I see is

Here: Here: Here: Here: Here: Here: Here: Here: Here: Here: Here: Here: Here: Here: Here:

Answer 1

As others have mentioned, you're getting confused as to when you should use the $ and @ symbols. (To be fair, it's not always obvious in Perl.) The Perl reference tutorial link glenn gave is the best resource. Maybe some examples will help:

use strict;
use warnings;

my @important_years = (1066, 1492, 1776);
my @recent_years    = (2010, 2012, 2014);

my $important_years_ref = \@important_years;
my $recent_years_ref    = \@recent_years;

my @redArray = ($important_years_ref, $recent_years_ref);

printf("%s\n", $redArray[0][0]);    # 1066
printf("%s\n", $redArray[0][1]);    # 1492
printf("%s\n", $redArray[0][2]);    # 1776

printf("%s\n", $redArray[1][0]);    # 2010
printf("%s\n", $redArray[1][1]);    # 2012
printf("%s\n", $redArray[1][2]);    # 2014

# Get a reference to the "important years" array
my $important_years_copy_ref = $redArray[0];
printf("%s\n", $important_years_copy_ref->[2]);  # 1776

# Or make brand new array by dereferencing
# the "important years" reference stored in @redArray
my @important_years_copy = @{$redArray[0]};
printf("%s\n", $important_years_copy[2]);        # 1776

Answer 2

Thanks to glenn jackman and ThisSuitIsBlackNot I was able to figure it out.

The issue is that the reference I was doing above was more or less correct but there was an error later in my code, the reference I went with was,

my $arrayRef = @redArray[$i];
my @redVal = @{$arrayRef};