Find all external links with Simple HTML Dom Parser and regular expressions? - php

Question

How can I find all external links on a page using regular expressions and Simple HTML DOM Parser? I have the following code to find all links.
<?php
include_once('simple_html_dom.php');
$url = "http://www.tokyobit.com";
$html = new simple_html_dom();
$html->load_file($url);
foreach($html->find('a') as $a){
echo $a;
}
?>
How can I add a regular expression to find all links starting with http://, https:// or ftp://?
foreach($html->find('a') as $a){
$regex = ; //regex here
if(preg_match_all($regex, $a, $matches)){
foreach($matches as $match){
echo $match . '<br />';
}
}
}

Answer 1

Change the $regex variable to:
$regex = "#(https?|ftp)://.#";

Answer 2

You can use a custom strpos to use an array as a needle
You'll first need this function
function strposa($haystack, $needle, $offset=0) {
if(!is_array($needle)) $needle = array($needle);
foreach($needle as $query) {
if(strpos($haystack, $query, $offset) !== false) return true; // stop on first true result
}
return false;
}
Then in your code
$needle = array("ftp://","http://","https://");
foreach($html->find('a') as $a){
if(strposa($a, $needle){
echo $matches;
}
}

Answer 3

Try this:
foreach($html->find('a') as $a){
if(preg_match('#^(?:https?|ftp)://.+$#', $a->href)){
echo $matches;
}
}

Answer 4

You can do it like this:
include_once('simple_html_dom.php');
$url = "http://www.tokyobit.com";
$html = new simple_html_dom();
$html->load_file($url);
$result = array();
foreach($html->find('a') as $a){
$href = $a->href;
if (strpos($href, '://', 3)!==false) $result[] = $href;
}
print_r($result);