# To find unique words in files:
#!/usr/bin/perl 
use warnings;

use List::Compare;  # Module       

# To enter many files: 
 my $entry; my @a; 

# Use of do-until loop:       
 do {print"\n\n  Press 1 to enter a new file or 2 to exit: \n"; # do LOOP
    $entry=<STDIN>; chomp ($entry);

       $file_no=0;  
   if ($entry==1) {$file_no++; # if LOOP starts   

   # Upload the files: 
    print "\n      Enter the filename:  "; 
    $file=<STDIN>; 
    chomp $file; 
    ############################
    # open the file, or exit:  
    ############################
       unless ( open(FILE, $file) ) {
       print "Cannot open file \"$file\"\n\n";
       exit;} 
    @string = <FILE>;   
    close FILE;
    $string=join(" ",@string);
    $string=~ s/\s//gi;     
    push @all,$string; 
    }  # End of if LOOP 

} until ($entry==2); # End of do-until LOOP     
###############################################

################################################
           $fnum=0; $wnum=0; 
foreach $item (@all) {$fnum++;     # 1st foreach LOOP for all files
       @file_words=();             # To empty array
  while ($item=~ /[A-Za-z].*?,/g)  # While LOOP2 starts                                   
     { $wnum++;   
       $word=$&;          
       $word=~ s/,//g;
       $word=~ s/\s//g; 
       
       push @file_words,$word;     

      } # while LOOP2 ends for all words in file 
     $num_all_words=@file_words;  

print "\n File No. $fnum
 Total Words: $num_all_words
 Words are:\n"; 
print join ("\n",@file_words);
print "\n\n\n"; 
  push @s,\@file_words;     


} # foreach LOOP ends 

     $ele_no=@s;    
print "\n\n Elements No.: $ele_no\n
 Final Array: @s\n\n"; 

 $all=List::Compare->new(@s); # Use of module function

    @file1=$all->get_unique(0);        
    @file2=$all->get_unique(1);
    @file3=$all->get_unique(2);         
     
print "\n\n Unique Words in Files:\n\n
 file1: @file1\n
 file2: @file2\n
 file3: @file3\n\n";   
                    
exit; 
####################

##</code><code>##

bat,    
cat, 


##</code><code>##

rat,
bat,


##</code><code>##

 
bat,
dog,


##</code><code>##

C:\Users\x\Desktop>m.pl

  Press 1 to enter a new file or 2 to exit:
1

      Enter the filename:  1.txt


  Press 1 to enter a new file or 2 to exit:
1

      Enter the filename:  2.txt


  Press 1 to enter a new file or 2 to exit:
1

      Enter the filename:  3.txt


  Press 1 to enter a new file or 2 to exit:
2

 File No. 1
 Total Words: 2
 Words are:
bat
cat

 File No. 2
 Total Words: 2
 Words are:
rat
bat

 File No. 3
 Total Words: 2
 Words are:
bat
dog


 Elements No.: 3

 Final Array: ARRAY(0x2902f5c) ARRAY(0x2902f5c) ARRAY(0x2902f5c)

 Unique Words in Files:


 file1:

 file2:

 file3:  
####################


##</code><code>##

Elements No.: 3

 Final Array: ???

 Unique Words in Files:


 file1: cat

 file2: rat

 file3: dog