How to make sure sure that a string contains a valid/well formed url?

Question

How to make sure that a string contains a valid/well formed url?

I need be sure the url in the string is well formed.

It must contain http:// or https://

and .com or .org or .net or any other valid extension

I tried some of the answers found here in SO but all are accepting "www.google.com" as valid.

In my case the valid url needs to be http://www.google.com or https://www.google.com.

The www. part is not an obligation, since some urls dont use it.

FILTER_VALIDATE_URL is not acceptible because "localhost" is a valid url on it, but cant be on my system. — Lucas Matos, Oct 14 '12 at 16:20

score 3 · Accepted Answer · edited May 23 '17 at 12:28

3

Take a look at the answer here: PHP regex for url validation, filter_var is too permisive

filter_var() could be just fine for you, but if you need something more powerful, you'll have to use regex.

Additionally with the code from here, you can sub-in any regex that suits your needs:

<?php 
    $regex = "((https?|ftp)\:\/\/)?"; // SCHEME 
    $regex .= "([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?"; // User and Pass 
    $regex .= "([a-z0-9-.]*)\.([a-z]{2,3})"; // Host or IP 
    $regex .= "(\:[0-9]{2,5})?"; // Port 
    $regex .= "(\/([a-z0-9+\$_-]\.?)+)*\/?"; // Path 
    $regex .= "(\?[a-z+&\$_.-][a-z0-9;:@&%=+\/\$_.-]*)?"; // GET Query 
    $regex .= "(#[a-z_.-][a-z0-9+\$_.-]*)?"; // Anchor 
?> 

Then, the correct way to check against the regex list as follows: 

<?php 
       if(preg_match("/^$regex$/", $url)) 
       { 
               return true; 
       } 
?>

edited May 23 '17 at 12:28

Community

1
1

answered Oct 14 '12 at 16:18

vladko

1,013
14
21

yeah, but i dont have sufficient knowledge to make a regex to deal with my needs. – Lucas Matos Oct 14 '12 at 16:28
but it's right in the answer at the link :) – vladko Oct 14 '12 at 16:31
yesh but on this expression in the link the http part is optional, i need that part. – Lucas Matos Oct 14 '12 at 16:35
thanks, i changed `"((https?|ftp)\:\/\/)?"; // SCHEME` to `"(https?|ftp)\:\/\/"; // SCHEME` to make it mandatory. Looks like its fine now. – Lucas Matos Oct 14 '12 at 17:02

score 1 · Answer 2 · answered Oct 14 '12 at 16:18

1

YOU can do this by using php filter_var function

$valid=filter_var($url, FILTER_VALIDATE_URL)

if($valid){
//your code
}

answered Oct 14 '12 at 16:18

StaticVariable

5,253
4
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score 0 · Answer 3 · answered Oct 14 '12 at 16:20

there's a curl solution:

function url_exists($url) {
    if (!$fp = curl_init($url)) return false;
    return true;
}

and there's a fopen solution (if you don't have

function url_exists($url) {
    $fp = @fopen('http://example.com', 'r'); // @suppresses all error messages
    if ($fp) {
        // connection was made to server at domain example.com
        fclose($fp);
        return true;
    }
    return false;
}

score 0 · Answer 4 · answered Oct 14 '12 at 16:23

0

filter_var($url, FILTER_VALIDATE_URL) can be first used to make sure you are dealing with a valid URL.

Then you have more conditions that can be tested by assuming the URL is indeed valid with parse_url:

$res = parse_url($url);
return ($res['scheme'] == 'http' || $ret['scheme'] == 'https') && $res['host'] != 'localhost');

answered Oct 14 '12 at 16:23

SirDarius

41,440
8
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Can you pls explain me how to use it? – Lucas Matos Oct 14 '12 at 16:29
@LucasMatos I believe my example is quite clear. Is there something you do not understand ? – SirDarius Oct 14 '12 at 17:25

How to make sure sure that a string contains a valid/well formed url?

4 Answers4