# Enter the tags to check for. Can only handle tags with
# no attributes at the moment
@tags = qw(b i u); 

# Put it in some HTML 
$html = "<b>Hello</b><u>Hello</i>";  # i.e. no </u> and <i> tag

# Iterate through each tag 
foreach $tag (@tags) { 

	# If $html contains that tag 
	while (($html =~ /<$tag>/i) or ($html =~ /<\/$tag>/i)) { 

		# If it contains the opening tag, keep count
		# of many opening tags there are. 
		if ($html =~ /<$tag>/i) { 
			$opening++; 
		}

          	# If it contains the closing tag, keep count
		# of many closing tags there are.
		if ($html =~ /<\/$tag>/i) {
			$closing++;
		}

                # Remove the tags for the next iteration
		$html =~ s/<$tag>//si;
		$html =~ s/<\/$tag>//si; 

	}

        # If the number of opening tags and closing tags 
	# don't match, then something is wrong 
	if ($opening != $closing) { 
		if ($opening > $closing) { 
		     	# More opening than closing, therefore
			# missing closing
			print "Warning, missing </$tag> tag\n"; 
		} else {
			print "Warning, missing <$tag> tag\n"; 
		}
	}

 	# Prepare for next iteration
	$opening = $closing = undef; 
}