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

for ($i=0;$i<5;$i++) {
$x{$i}="x";

}

print Dumper($x);

##</code><code>##

Global symbol "$i" requires explicit package name at noname.pl line 5.
Global symbol "$i" requires explicit package name at noname.pl line 5.
Global symbol "$i" requires explicit package name at noname.pl line 5.
Global symbol "%x" requires explicit package name at noname.pl line 6.
Global symbol "$i" requires explicit package name at noname.pl line 6.
Global symbol "$x" requires explicit package name at noname.pl line 10.
Execution of noname.pl aborted due to compilation errors.

##</code><code>##

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

my %x;

for (my $i = 0; $i < 5; $i++) {
    $x{$i} = "x";
}

print Dumper (\%x);

##</code><code>##

#1/ Perl for loop:
my %x;

for my $i (0 .. 4) {
    $x{$i} = "x";
}

#2/ For as a statement modifier
$x{$_} = 'x' for 0 .. 4;

#3/ map generating hash key/value pairs:
%x = map {$_ => 'x'} 0 .. 4;

#4/ hash slice and x operator:
@x{0 .. 4} = ('x') x 5;