the program has to find successful match if the filename is following
Case 1 : test_file_name.dat (all lower case)
Case 2 : TEST_FILE_NAME.DAT (all upper case)
Case 3 : Test_File_Name.dat (Mixed)

##</code><code>##

lc $name eq 'test_file_name.dat'

##</code><code>##

    $datfile = uc(test_file_name.dat);

##</code><code>##

use strict;    # and
use warnings;  # as well

##</code><code>##

        open(FL, $File::Find::name);