php - Best way to check if a URL is valid

Question

I want to use PHP to check, if string stored in $myoutput variable contains a valid link syntax or is it just a normal text. The function or solution, that I'm looking for, should recognize all links formats including the ones with GET parameters.

A solution, suggested on many sites, to actually query string (using CURL or file_get_contents() function) is not possible in my case and I would like to avoid it.

I thought about regular expressions or another solution.

Answer 1

You can use a native Filter Validator

filter_var($url, FILTER_VALIDATE_URL);

Validates value as URL (according to ? http://www.faqs.org/rfcs/rfc2396), optionally with required components. Beware a valid URL may not specify the HTTP protocol http:// so further validation may be required to determine the URL uses an expected protocol, e.g. ssh:// or mailto:. Note that the function will only find ASCII URLs to be valid; internationalized domain names (containing non-ASCII characters) will fail.

Example:

if (filter_var($url, FILTER_VALIDATE_URL) === FALSE) {
    die('Not a valid URL');
}