use strict;
my $str = 'Below, we present an introduction to advanced regular expressions, with eight commonly used concepts and examples.
Each example outlines a simple way to match patterns in complex strings.
If you do not yet have experience with basic regular expressions, have a look at this article to get started. The syntax used here matches PHP regular expressions.Regular expressions (or regex) are a powerful way to traverse large strings in order to find information. They rely on underlying patterns in a string’s structure to work their magic. Unfortunately, simple regular expressions are unable to cope with complex patterns and symbols. To deal with this dilemma, you can use advanced regular expressions.';
my $regex = qr/(((^|\n*).{1,42}?)(\n))|(\n*.{1,42})( |\n|$)/smp;
my $subst = '\\2\\5\\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