PHP，使用域扩展的url验证

Question

I've been trying to use FILTER_VALIDATE_URL, as well as regex, to validate url, but no luck.

For example:

$url = "http://www.stackoverflow";

    if (preg_match("/^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$/", $url)) {
      echo "URL is valid";
    }
    else {
      echo "URL is invalid";
    }
        echo("$url is not a valid URL");
    }

The above will show valid url, even if domain extension is omitted, the same goes for FILTER_VALIDATE_URL

What I would like is to validate url only if entered in following format:

http://www.stackoverflow.com
https://www.stackoverflow.com
http://stackoverflow.com
https://stackoverflow.com

anything like:

http://stackoverflow
https://stackoverflow
http://www.stackoverflow
https://www.stackoverflow

should be invalid.

And of course it should work with any type of domain extension.

Answer 1

If you want to work with FILTER_VALIDATE_USE, acording to documentation, you should use:

FILTER_FLAG_HOST_REQUIRED - URL must include host name (like http://www.example.com)

like:

<?php
$url = "https://www.stackoverflow.com";

if (filter_var($url, FILTER_VALIDATE_URL, FILTER_FLAG_HOST_REQUIRED)) {
    echo("$url is a valid URL");
} else {
    echo("$url is not a valid URL");
}
?>

And this should work. Hope it helps!

Edit:

The results of the code:

stackoverflow.com is not a valid URL

http://stackoverflow.com is a valid URL

http://www.stackoverflow.com is a valid URL

ww.stackoverflow.com is not a valid URL

http://stackoverflow is a valid URL

As @mickmackusa said, I removed the regex snippet, if you want regex, you could use:

validate url with regular expressions

Or:

URL Validation REGEX - URL just valid with http://