use strict;
my $str = 'There are usually about 200 words in a paragraph, but this can vary widely. Most paragraphs focus on a single idea that\'s expressed with an introductory sentence, then followed by two or more supporting sentences about the idea. A short paragraph may not reach even 50 words while long paragraphs can be over 400 words long, but generally speaking they tend to be approximately 200 words in length.';
my $regex = qr/([^\v]{0,80})(?:\s|$)/mp;
my $subst = '$1\\n';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html