Parse Website for URLs - php

Question

Just wondering if someone can help me further with the following. I want to parse the URL on this website:http://www.directorycritic.com/free-directory-list.html?pg=1&sort=pr
I have the following code:
<?PHP
$url = "http://www.directorycritic.com/free-directory-list.html?pg=1&sort=pr";
$input = #file_get_contents($url) or die("Could not access file: $url");
$regexp = "<a\s[^>]*href=(\"??)([^\" >]*?)\\1[^>]*>(.*)<\/a>";
if(preg_match_all("/$regexp/siU", $input, $matches)) {
// $matches[2] = array of link addresses
// $matches[3] = array of link text - including HTML code
}
?>
Which does nothing at present and what I need this to do is scrap all the URL in the table for all 16 pages and would really appreciate some help with how to amend the above to do that and output URL into a text file.

Answer 1

Use HTML Dom Parser
$html = file_get_html('http://www.example.com/');
// Find all links
$links = array();
foreach($html->find('a') as $element)
$links[] = $element->href;
Now links array contains all URLs of given page and you can use these URLs to parse further.
Parsing HTML with regular expressions is not a good idea. Here are some related posts:
Using regular expressions to parse HTML: why not?
RegEx match open tags except XHTML self-contained tags
EDIT:
Some Other HTML Parsing tools as described by Gordon in comments below:
phpQuery
Zend_Dom
QueryPath
FluentDom

Answer 2

You really shouldn’t use regular expressions to parse HTML as it’s to error prone.
Better use an HTML parser like the one of PHP’s DOM library:
$code = file_get_contents($url);
$doc = new DOMDocument();
$doc->loadHTML($code);
$links = array();
foreach ($doc->getElementsByTagName('a') as $element) {
if ($element->hasAttribute('href')) {
$links[] = $elements->getAttribute('href');
}
}
Note that this will collect the URI references as they appear in the document and not as an absolute URI. You might want to resolve them before.
It seems that PHP doesn’t provide an appropriate library (or I haven’t found it yet). But see RFC 3986 – Reference Resolution and my answer on Convert a relative URL to an absolute URL with Simple HTML DOM? for further details.

Answer 3

Try this method
function getinboundLinks($domain_name) {
ini_set('user_agent', 'NameOfAgent (<a class="linkclass" href="http://localhost">http://localhost</a>)');
$url = $domain_name;
$url_without_www=str_replace('http://','',$url);
$url_without_www=str_replace('www.','',$url_without_www);
$url_without_www= str_replace(strstr($url_without_www,'/'),'',$url_without_www);
$url_without_www=trim($url_without_www);
$input = #file_get_contents($url) or die('Could not access file: $url');
$regexp = "<a\s[^>]*href=(\"??)([^\" >]*?)\\1[^>]*>(.*)<\/a>";
//$inbound=0;
$outbound=0;
$nonfollow=0;
if(preg_match_all("/$regexp/siU", $input, $matches, PREG_SET_ORDER)) {
foreach($matches as $match) {
# $match[2] = link address
# $match[3] = link text
//echo $match[3].'<br>';
if(!empty($match[2]) && !empty($match[3])) {
if(strstr(strtolower($match[2]),'URL:') || strstr(strtolower($match[2]),'url:') ) {
$nonfollow +=1;
} else if (strstr(strtolower($match[2]),$url_without_www) || !strstr(strtolower($match[2]),'http://')) {
$inbound += 1;
echo '<br>inbound '. $match[2];
}
else if (!strstr(strtolower($match[2]),$url_without_www) && strstr(strtolower($match[2]),'http://')) {
echo '<br>outbound '. $match[2];
$outbound += 1;
}
}
}
}
$links['inbound']=$inbound;
$links['outbound']=$outbound;
$links['nonfollow']=$nonfollow;
return $links;
}
// ************************Usage********************************
$Domain='<a class="linkclass" href="http://zachbrowne.com">http://zachbrowne.com</a>';
$links=getinboundLinks($Domain);
echo '<br>Number of inbound Links '.$links['inbound'];
echo '<br>Number of outbound Links '.$links['outbound'];
echo '<br>Number of Nonfollow Links '.$links['nonfollow'];