Question

I need some function to check is the given value is a url.

I have code:

<?php
$string = get_from_db();
list($name, $url) = explode(": ", $string);
if (is_url($url)) {
    $link = array('name' => $name, 'link' => $url);
} else {
    $text = $string;
}
// Make some things
?>

Answer 1

If you’re running PHP 5 (and you should be!), just use filter_var():

function is_url($url)
{
    return filter_var($url, FILTER_VALIDATE_URL) !== false;
}

Addendum: as the PHP manual entry for parse_url() (and @Liutas in his comment) points out:

This function is not meant to validate the given URL, it only breaks it up into the above listed parts. Partial URLs are also accepted, parse_url() tries its best to parse them correctly.

For example, parse_url() considers a query string as part of a URL. However, a query string is not entirely a URL. The following line of code:

var_dump(parse_url('foo=bar&baz=what'));

Outputs this:

array(1) {
  ["path"]=>
  string(16) "foo=bar&baz=what"
}