I'd just:

my @arr = map {$_ * $_} qw( 1 2 3 4 5 6 7 8);
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or if the array already exists:

$_ *= $_ for @arr;
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Somehow you have to loop through the array and modify the values in place with the exponentiation operator (or the multiplication operator). perlsyn describes most of the interesting parts in the section on "Foreach Loops".

Is this you are expecting.


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


my @array=(1,2,3);
print Dumper \@array;
my $len=$#array;
while($len>=0)
{
        $array[$len]=$array[$len]*$array[$len];
        $len--;
}
print Dumper \@array;
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Or use the following way.


my @array=(1,2,3);
foreach (@array)
{
        $_=$_*$_;
}
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The latter is much better, though you could multiply and assign in place with =*:

for (@array)
{
    $_ *= $_;
}
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... or even use postfix iteration:

$_ *= $_ for @array;

For completeness:

@a = 1..10;;
$_ **= 2 for @a;;
print @a;;
1 4 9 16 25 36 49 64 81 100
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Thanks to all..

#!usr/bin/perl -w
use strict;

my @arr = qw( 1 2 3 4 5 6 7 8); 
square(\@arr);

sub square
{
   my $arrayref = shift;
   foreach my $item (@$arrayref)
   {
      $item **=2; #or
     #$item *=$item;
   }
}

foreach (@arr)
{
   print "$_\n";
}
__END__
prints:
1
4
9
16
25
36
49
64
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my @arr = qw( 1 2 3 4 5 6 7 8); 
foreach (@arr)
{
  $_*=$_;
}
#or 
@arr = map($_*$_}@arr;
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pajout@balvan:~$ perl -e 'my @a = (1,2,3); print join(",", map {$_*$_}
+ @a)."\n";'
1,4,9
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