Re: How can I define the subroutine to get the result of the appended string i.e. ATGCTTTT?

[Marshall]

You need to export the DNAappend symbol. I would use DNAlibrary or some such name, presuming that you will add other DNA routines to this thing.

#!/usr/bin/perl -w
use strict;

use DNAlibrary;

my $a='ATGC';
my $b='TTTT';
print"\n\n";
print DNAappend($a,$b), "\n\n";  #ATGCTTTT

#!/usr/bin/perl -w
use strict;

package DNAlibrary;   #FILE name should be DNAlibrary.pm
use vars qw(@ISA @EXPORT @EXPORT_OK %EXPORT_TAGS $VERSION);
use Exporter;
our $VERSION=1.0;
our @ISA = qw(Exporter);
our @EXPORT = qw(DNAappend);#these are the default exports
our @EXPORT_OK = qw();      #these are export on request

sub DNAappend {
  my ($head,$tail)=@_;
  return ($head.$tail)
  }
1;