use strict;
use warnings;

my @arr = (1..10);

sub test_this {
	print "Inside the sub, before the map \@arr: @arr\n";
	print "Inside the sub, before the map \@\_ = @_\n";
	@arr = map { 2 * $_ } @_;
	print "Inside the sub, after the map \@arr: @arr\n";
	print "Inside the sub, after the map \@\_ = @_\n";
}
print "Before calling the sub test_this \@arr: @arr\n";
&test_this(@arr);
print "After calling the sub test_this \@arr: @arr\n";



##</code><code>##

pritesh@t430:~$ perl test.pl 
Before calling the sub test_this @arr: 1 2 3 4 5 6 7 8 9 10
Inside the sub, before the map @arr: 1 2 3 4 5 6 7 8 9 10
Inside the sub, before the map @_ = 1 2 3 4 5 6 7 8 9 10
Inside the sub, after the map @arr: 2 4 6 8 10 12 14 16 18 20
Inside the sub, after the map @_ = 2 4 6 8 10 12 14 16 18 20
After calling the sub test_this @arr: 2 4 6 8 10 12 14 16 18 20
pritesh@t430:~$