#The idea is to read the first line of the file and see how many columns we have, then we proceed accordingly, column-by-column
open (INFILE10, '<', 'ex1.dat') or die "File ex1.dat does not exist!\n";
my $firstLine = <INFILE10>; 
close INFILE10;
my @array_firstLine=split(/\t/, $firstLine);
my $total_columns=scalar(@array_firstLine);
print "This file has $total_columns columns in total.\n";

for(my $k=1; $k<=$total_columns; $k++)
{
  print "Calculate sum for column $k\n";
  my $wanted_column_number=$k;    #this is the column that we want to sum up each time, until we finish the columns
  my $sum_of_column=0;
  open (INFILE10, '<', 'ex1.dat') or die "File ex1.dat does not exist!\n";
  while( my $line10 = <INFILE10>)
  {
    my @split_line10 = split(/\t/, $line10);
    my $respective_element = $split_line10[$k-1];
    $sum_of_column = $sum_of_column + $respective_element;
  }
  close INFILE10;

  print "The sum for column $k is: $sum_of_column.\n";
}