Question

I use XPath to parse a HTML webpage for fetching all internal links. DOMXPath will return all links provided in href. How can I separate internal an external links?

I introduce a series of string checks to remove external links; but the problem is that there are different ways to link internal pages such as

    page.html
    /page.html
    http://domain.com/page.html
    http://subdomain.domain.com/page.html
    ....

What is the safest way to distinguish internal links (any link to the present domain including its subdomains) and external links (to any other domain).

Answer 1

Use substr() to see if the first 4 characters are http.

If so, use the parse_url() function to check whether the host is the same.
If not, it’s internal.