Array ref empty when received by a sub

Question

I am trying to access elements of arrays by reference, passing references into a sub. Here is my code snippet:

my @arr1 = (1,2);
my @arr2 = (3,4);
my @arr3;

push @arr3, \@arr1;
push @arr3, \@arr2;

for my $i (@arr3) {
  print "$i\n";
}

print "Entered Sub func()\n";

for my $i (@arr3) { 
  func($i);
}

sub func{
  my $par = shift;
  print $par."\n";
}
print "------------------------\n";

for my $elem(@$par) {
  print $elem."\n";
}

And here is the ouput:

C:\Users\ag194y>perl arrs.pl
ARRAY(0x357b28)
ARRAY(0x3575e8)
Entered Sub func()
ARRAY(0x357b28)
ARRAY(0x3575e8)
------------------------

C:\Users\ag194y>

I was expecting to access the elements of @arr1 and a@rr2 with the for loop in the sub, but it looks like array refs are empty. What am I doing wrong? Many thanks.

There is no `for` loop in your sub. If you had used `use strict; use warnings;`, perl would've told you. — melpomene, Jun 03 '17 at 20:23
What is it with all the badly-formatted code we're seeing recently? I've fixed it for you, but please do it yourself next time. — Dave Cross, Jun 05 '17 at 08:03

score 2 · Accepted Answer · answered Jun 03 '17 at 20:33

I think the problem is, loop being outside of func. You are calling func twice, and only after that you are looping through $par, which is undefined at the time.

You might be looking for something like:

sub func{
  my $par = shift;

  print $par."\n";
  print "------------------------\n";

  for my $elem (@$par){
    print $elem."\n";
  }
}

Array ref empty when received by a sub

1 Answers1