Find and replace text from *.files in Perl

use strict;
use warnings;
use Cwd;

use File::Find;

my $search_pattern='sex' ;
my $replace_pattern = 'xes';

# my $replace_pattern = 'bar';
my $file_pattern ='.*?dat';
find(\&d, cwd);

sub d {
my $file = $File::Find::name;
$file =~ s,/,\\,g;

return unless -f $file;
return unless $file =~ /$file_pattern/;
use Tie::File ;

tie my @file_array , 'Tie::File', $file , memory => 100_000_000 or die "I cannot find the $file" ;
foreach my $line (@file_array) #foreach line of the file
{
$line =~ s/$search_pattern/$replace_pattern/igo ;
}
untie @file_array ;

}