Extract URL from string

Question

I'm trying to find a reliable solution to extract a url from a string of characters. I have a site where users answer questions and in the source box, where they enter their source of information, I allow them to enter a url. I want to extract that url and make it a hyperlink. Similar to how Yahoo Answers does it.

Does anyone know a reliable solution that can do this?

All the solutions I have found work for some URL's but not for others.

Thanks

Solution 1

$string = preg_replace('/https?:\/\/[^\s"<>]+/', '<a href="$0" target="_blank">$0</a>', $string);

It only matches http/https, but that's really the only protocol you want to turn into a link. If you want others, you can change it like this:

$string = preg_replace('/(https?|ssh|ftp):\/\/[^\s"]+/', '<a href="$0" target="_blank">$0</a>', $string);

Solution 2

There are a lot of edge cases with urls. Like url could contain brackets or not contain protocol etc. Thats why regex is not enough.

I created a PHP library that could deal with lots of edge cases: Url highlight.

You could extract urls from string or directly highlight them.
Example:

<?php

use VStelmakh\UrlHighlight\UrlHighlight;

$urlHighlight = new UrlHighlight();

// Extract urls
$urlHighlight->getUrls("This is example http://example.com.");
// return: ['http://example.com']

// Make urls as hyperlinks
$urlHighlight->highlightUrls('Hello, http://example.com.');
// return: 'Hello, <a href="http://example.com">http://example.com</a>.'

For more details see readme. For covered url cases see test.