What have you tried? See Arrays: A Tutorial/Reference from the tutorials section of this site, or http://learn.perl.org for further resources on learning perl.

@array[0..$ix] = @array[$ix, 0..$ix-1]
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my $element = 'dog';
my $last = $element;
for (@array) {
  ($_, $last) = ($last, $_);
  last if $last eq $element;
}
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Using unshift and splice in a loop will do the trick in this special case as we are not changing the size of the array so the subscript isn't mucked up.

$ perl -E '
> @arr = qw{ apple ball cat dog elephant fish dog budgie };
> for ( 1 .. $#arr )
> {
>     unshift @arr, splice @arr, $_, 1 if $arr[ $_ ] eq q{dog};
> }
> say for @arr;'
dog
dog
apple
ball
cat
elephant
fish
budgie
$
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I hope this is helpful.

@array = sort {
    ($a eq 'dog' ? 0 : 1)
        <=>
    ($b eq 'dog' ? 0 : 1)
} @array;
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Alternatively you can chose not to learn and use the code below

use strict;
use warnings;

my @array = ("apple","ball","cat","dog","elephant"); 
@array = drag_to_front("dog", @array);
print join(",", @array),"\n";

sub drag_to_front{
   my ($wanted, @array)=@_;
   my @new_array;
   for my $element (@array){
      if ($element eq $wanted){
         unshift @new_array, $element;
      }
      else{
         push @new_array, $element;
      }
   }
   return @new_array;
}
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