$pageData = file_get_contents('http://geekforbrains.com');
if(preg_match_all('/<a\s+href=["\']([^"\']+)["\']/i', $pageData, $links, PREG_PATTERN_ORDER))
    return array_unique($links[1]);
return false;

$pageData = file_get_contents('http://geekforbrains.com');
if(preg_match_all('/<a\s+href=["\']([^"\']+)["\']/i', $pageData, $links, PREG_PATTERN_ORDER))
    return $links[1];
return false;

These 4 lines of code can be used to extract and return all links from any page using regex patterns. If links are found, an array is returned, else boolean false is returned.

Extract all links from a page using Regex

regex, file, html, links

PHP