Solved by adding chomp

while ( <SFILE> ) {
  chomp
 my @words = split /(?=\\)/;
    for my $word ( @words ) {
        $word = $words{ $word } if exists $words{ $word };
        }
    print TFILE "@words\n<br>";
}
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another question: is it OK, if I used hash array my "data" (DFILE) on that program contain about 5000 lines ?

my %words;
while (<DFILE>) {
    chomp;    
    my ($key, $val) = split /:/;
    $words{$key} = $val;
};
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