1\n

##</code><code>##

     $_ =~ s/$_/$_ 1.0/g;

##</code><code>##

     1\n 1.0

##</code><code>##

foreach $txtfile (glob("*.TXT")) {
   print $txtfile;
   print "\n";
   open FILE, "$txtfile";
   open NEWFILE, ">$txtfile.tmp";
   while (<FILE>){
      chomp $_;
      if ($. == 1){
         $_ .= " 1.0";     # i.e. $_ = $_ . " 1.0";
      }
      print NEWFILE $_, "\n";
   }
   close FILE;
   close NEWFILE;
}

##</code><code>##

foreach $txtfile (glob("*.TXT")) {
   print $txtfile;
   print "\n";
   open FILE, "$txtfile";
   open NEWFILE, ">$txtfile.tmp";
   while (<FILE>){
      $_ =~ s/\n/ 1.0\n/ if $. = 1;
      print NEWFILE $_;
   }
   close FILE;
   close NEWFILE;
}