Special characters from forms using as variables on the same page

Question

I've ran into an issue with special characters being used as variables.

Heres my HTML that has something to do with characters:

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
...
<form class="nav-search left" method="POST" enctype="application/x-www-form-urlencoded">
    <input name="summoner_name" type="text" placeholder="Summoner Name" required autofocus />
</form>

Heres the PHP which is trying to get the $_POST:

$summoner = htmlspecialchars($_POST['summoner_name']);
$summoner_name = strtolower($summoner);

-> outputs nothing, as it isn't read properly.

Letters such as Śý will be used, and I think these are from extended-latin

Answer 1

Using this walkthrough as a jumping off point, I would say:

First

...verify that your application is emitting the Content-Type: text/html; charset=utf-8 header. There's really no reason not to, and it's really simple.

Next

...the first place you may have a real issue is your form. Again referencing the above link the encoding to be used for application/x-www-form-urlencoded data is practically undefined.

Make sure your form is using the attribute accept-charset set to "utf-8" (accept-charset="utf-8").

One More

...If you aren't using a database in here, then there's nothing to do there, but if you ever store this data in a database, that's almost definitely where the mis-encoding is happening.

There's a lot that could go wrong in the database - from connecting, to how the data is stored, to how the data is retrieved. If you are using a database at all to store this data before it is sent back to the browser, take extra care to make sure the database is properly encoding and retrieving UTF-8 text.

Finally

...strtolower doesn't convert characters not represented by your locale. If your locale is, say, en-US, your special UTF-8 characters will not be converted, and you'll get an empty string (if there aren't any other characters).

If you were to use mb_strtolower, you could pass an encoding like: mb_strtolower($summoner, 'UTF-8'); This properly handles special characters.