use strict;
use warnings;
 
my $filename = 'C:\Users\William\Desktop\data.txt';
open(DONG,$filename)
  or die "Could not open file '$filename' $!";
 

my @line=<DONG>;
close DONG;
 
#while (my $row = <DONG>) {
#  chomp $row;
#  print "$row\n";
#}

my $out_filename = 'C:\Users\William\Desktop\data_out.txt'

#判断输出文件是否存在
if (-e $out_filename) {
    die ("Output file outfile already exists.\n");
}
open(OUTFILE,">$out_filename");
print OUTFILE ("@line\n");