Question

WHat will be the best practice to replace Unicode character in URL.
For example if I have a multilingual website and support East European languages

How should I format the URL that it always contains valid characters?

Answer 1

What you want todo is called slugify.

$slugified_url_part = iconv('utf-8', 'us-ascii//TRANSLIT', $url_part);

The above code will turn non ascii chars to it’s closest ascii char.
You should also trim whitespace and replace inner whitespace with a dash or underscore.
Making all chars lowercase is also common.

Slugify is handy for remembering URLS and SEO.
You could ofcourse use percent encoding but that can look ugly.