#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my @array = (
  { test => 1, test2 => 3},{ test => 1, test2 => 3},
  { test => 1, test2 => 3},{ test => 1, test2 => 3}
);

print Dumper \@array;

x(\@array);

print Dumper \@array;

sub x{
   my $p = shift;
   for my $i ( 0..3 ){
      $p->[$i]->{test2} = 'etwas anderes';
   }
}