#!/usr/bin/perl 
use warnings; 
use File::Glob(bsd_glob); 

do { @array=@array1;
  print"\n\n Press 1 to Enter New File or 2 to Combine:  ";
  $entry=<STDIN>; chomp $entry;  
############################ 
# Use of if Conditional:  
############################

  if ($entry==1) { 
  print"\n\n    Enter New File Name (.txt):  "; 
  $filename = <STDIN>; chomp $filename;
################################ 
# open the file, or exit:    ###
################################
 unless ( open(FILE, $filename) ) {
 print "Cannot open file \"$filename\"\n\n";
 exit;} 
 @DNA= <FILE>;
 close FILE;
 $DNA=join('',@DNA);    
 push @array, $DNA;
 @array1=@array;}      # Curly brace for entry1 ends:  
 
elsif ($entry==2)
  { @array1=@array; # Curly brace for entry2 starts
   $number=@array1; 
   print"\n\n No. of Elements in Joined Array: $number\n";
   print"\n Joined Array:\n";
   print @array1;           
# Use of foreach LOOP to view each element of joined array: 
 $num=0;  
 foreach my $element (@array1) { 
 $num++;    
 print"\n  Array No.$num of the Joined Array:\n"; 
 print $element;
 print"\n"; 
# Code to surround each element of joined array
# followd by comma i.e. [ ],  
 @element=split('',$element);  
$str1=sprintf '[%s],'x @element,@element; 
print"\n str1: $str1\n"; push @ARRAY1,$str1; 

      } # Curly brace for foreach ends: 

print"\n ARRAY:\n"; 
print @ARRAY1; print"\n"; 
# To produce all possible combinations of different elements: 
$combi=join('',map {'{'.join (',',@$_).'}'} @ARRAY1);  
@list=bsd_glob($combi); 
  
print"\n Results:\n"; 
print"\n @list\n"; 

   } # Curly brace for Entry 2 ends: 
} until ($entry==2); # Square bracket for do-until: 
exit;