Check if a string contains nothing but an URL in PHP

Question

I am wondering if this is a proper way to check, if a string contains nothing but an URL:

if (stripos($string, 'http') == 0 && !preg_match('/\s/',$string)) {
  do_something();
}

stripos() checks if the string starts with "http"
preg_match() checks if the string contains spaces

If not so, I assume that the string is nothing but an URL - but is that assumption valid? Are there better ways to achieve this?

possible duplicate of [the best way to check if a url is valid?](http://stackoverflow.com/questions/2058578/the-best-way-to-check-if-a-url-is-valid) — trejder, Jul 30 '15 at 09:46

score 161 · Accepted Answer · edited Sep 30 '15 at 11:24

161

if (filter_var($string, FILTER_VALIDATE_URL)) { 
  // you're good
}

The filters can be even more refined. See the manual for more on this.

edited Sep 30 '15 at 11:24

Limon Monte

answered Feb 21 '13 at 20:24

John Conde

Thanks a lot! (I think both answers came at the same time) – yotka Feb 22 '13 at 17:14
Thanks, this is better than parse_url($string), because anything with a colon (:) would get dinged as a url. Works alot better. Wish there was a way to detect if it was a url even if it did not have the http:// though. – alexander7567 Aug 06 '13 at 19:02
1

This failed to successfully validate a URL where I had the chracter `å` in it - but the URL was working. (Using PHP 7.0) – TheStoryCoder Aug 24 '17 at 02:44
1

This FAILED to validate valid URLs where they contain % chracters – Kyle KIM Apr 24 '18 at 14:38

score 10 · Answer 2 · edited Apr 09 '22 at 02:49

10

In PHP there is a better way to validate the URL:

if(filter_var('http://example.com', FILTER_VALIDATE_URL)) {
    echo 'this is URL';
}

edited Apr 09 '22 at 02:49

ScreamX

answered Feb 21 '13 at 20:25

Winston

score 1 · Answer 3 · edited Dec 20 '21 at 11:36

1

To more securely validate URLs (and those 'non-ascii' ones), you can

Check with the filter (be sure to check the manual on which filter suits your situation)

Check to see if there are DNS records

$string = idn_to_ascii($URL);
if(filter_var($string, FILTER_VALIDATE_URL) && checkdnsrr($string, "A")){
    // you have a valid URL
}

edited Dec 20 '21 at 11:36

JON

answered Nov 23 '18 at 13:26

Apps-n-Add-Ons

3 Answers3