Perl regexp to find an element inside an element - regex

Question

I need to find through regular expression from <div id="class1"> to end of </div>. I may also have as many <div> within its text inside it. Please find the code below
This is example <div id="class1">This is <div id="subclass1">This is </div> <div id="subclass2">This is </div> This is </div> This is example
I have tried the below code. But it gets only up to first </div> of <div id="subclass1">
Could any help me to solve this?
Code I tried to capture is:
<div id="class1">(?:(?!<\/div>).)*?</div>

Answer 1

Use a proper HTML parser.
use strict;
use warnings;
use feature qw( say );
use XML::LibXML qw( );
my $html = 'This is example <div id="class1">This is <div id="subclass1">This is </div> <div id="subclass2">This is </div> This is </div> This is example';
my $parser = XML::LibXML->new();
my $doc = $parser->parse_html_string($html);
my $root = $doc->documentElement();
for my $div ($root->findnodes('//div[#id="class1"]')) {
say "[", $div->toString(), "]";
}

Answer 2

$ echo 'This is example <div id="class1">This is <div id="subclass1">This is </div> <div id="subclass2">This is </div> This is </div> This is example' | sed -n 's/<div id="class1">\(.*\)<\/div>/\1/p'
This is example This is <div id="subclass1">This is </div> <div id="subclass2">This is </div> This is This is example

Answer 3

You should use appropriate HTML/XML parser. If you want to do it with regex for any reason, nested regex helps you. (Check perldoc perlre for detail.)
$re = qr{
(
<div[^>]*>
(?:(??{$re}) | [^<>]*)*
</div>
)
}x;
print "$1\n" if(/$re/o);

Answer 4

A lot of people always say "Use a proper HTML parser" to parse HTML and not regex. What some people fail to realize is that there are requirements to be met and those requirements might require regex.
<div id=".+?">.*</div> should work for you.
http://regexr.com?33336