A possible solution for the stars.pl program is as follows:

stars.pl

#!/usr/bin/perl
 
use warnings;
use strict;
 
#  stars.pl - solution for printing out an increasing number of asterisks,
#   from 1 to 5.  Uses a nested loop structure.  For variety, a for()
#   loop is used on the outside and a while loop is used on the inside.
#   Many different types of loops could be used in either place.
 
my ($i, $j);
 
for ($i = 1; $i <= 5 ; $i++)
{
    $j = 1;
    while ($j <= $i)
    {
	print '*';
	$j++;
    }
    print "\n";
}
 

Another possible solution is:

stars-foreach.pl

#!/usr/bin/perl
 
use warnings;
use strict;
 
#  stars-foreach.pl - solution for printing out an increasing number
#   of asterisks, #   from 1 to 5.  Uses a nested loop structure using
#   foreach loops.
 
my ($i, $j);
 
foreach $i (1..5)
{
    foreach $j (1..$i)
    {
	print '*';
    }
    print "\n";
}
 

A third possible solution is:

stars-xop.pl

#!/usr/bin/perl
 
# stars-xop.pl : alternate solution for stars.pl problem
#  uses the "x" operator which repeats a string (left operator)
#  a given number (right operator) of times.  This avoids the
#  need for a loop with $j.
 
use warnings;
use strict;
 
my $i;
 
for ($i = 1; $i <= 5 ; $i++)
{
    print '*' x $i, "\n";
}