use strict;
 
my $sequence = "This is a nice line ";
# Note: You should  use '\1' rather than '$1'.
$sequence =~ s/(\S{1,80})/\1\n/g;
print "*",$sequence,"*\n";

##</code><code>##

*This
 is
 a
 nice
 line
 *

##</code><code>##

use strict;
 
my $sequence = "12345678901234567890123456789012345678901234567890123456789012345678901234567890123456";
my $len = int(length($sequence)/80);
my @seq = ($len > 0) ? unpack("(A80)$len A*",$sequence) : $sequence;
 
print "*",join("\n",@seq),"*\n";