How to remove diacritics from text?

Question

I am making a swedish website, and swedish letters are å, ä, and ö.

I need to make a string entered by a user to become url-safe with PHP.

Basically, need to convert all characters to underscore, all EXCEPT these:

 A-Z, a-z, 1-9

and all swedish should be converted like this:

'å' to 'a' and 'ä' to 'a' and 'ö' to 'o' (just remove the dots above).

The rest should become underscores as I said.

Im not good at regular expressions so I would appreciate the help guys!

Thanks

NOTE: NOT URLENCODE...I need to store it in a database... etc etc, urlencode wont work for me.

Answer 1

If you're just interested in making things URL safe, then you want urlencode.

Returns a string in which all non-alphanumeric characters except -_. have been replaced with a percent (%) sign followed by two hex digits and spaces encoded as plus (+) signs. It is encoded the same way that the posted data from a WWW form is encoded, that is the same way as in application/x-www-form-urlencoded media type. This differs from the » RFC 1738 encoding (see rawurlencode()) in that for historical reasons, spaces are encoded as plus (+) signs.

If you really want to strip all non A-Z, a-z, 1-9 (what's wrong with 0, by the way?), then you want:

$mynewstring = preg_replace('/[^A-Za-z1-9]/', '', $str);

Answer 2

as simple as

 $str = str_replace(array('å', 'ä', 'ö'), array('a', 'a', 'o'), $str); 
 $str = preg_replace('/[^a-z0-9]+/', '_', strtolower($str));

assuming you use the same encoding for your data and your code.

Answer 3

and all swedish should be converted like this:

'å' to 'a' and 'ä' to 'a' and 'ö' to 'o' (just remove the dots above).

Use normalizer_normalize() to get rid of diacritical marks.

The rest should become underscores as I said.

Use preg_replace() with a pattern of [\W] (i.o.w: any character which doesn't match letters, digits or underscore) to replace them by underscores.

Final result should look like:

$data = preg_replace('[\W]', '_', normalizer_normalize($data));

Answer 4

One simple solution is to use str_replace function with search and replace letter arrays.

Answer 5

This should be useful which handles almost all the cases.

function Unaccent($string)
{
    return preg_replace('~&([a-z]{1,2})(?:acute|cedil|circ|grave|lig|orn|ring|slash|th|tilde|uml|caron);~i', '$1', htmlentities($string, ENT_COMPAT, 'UTF-8'));
}

Answer 6

If intl php extension is enabled, you can use Transliterator like this :

protected function removeDiacritics($string)
{
    $transliterator = \Transliterator::create('NFD; [:Nonspacing Mark:] Remove; NFC;');
    return $transliterator->transliterate($string);
}

To remove other special chars (not diacritics only like 'æ')

protected function removeDiacritics($string)
{
    $transliterator = \Transliterator::createFromRules(
        ':: Any-Latin; :: Latin-ASCII; :: NFD; :: [:Nonspacing Mark:] Remove; :: NFC;',
        \Transliterator::FORWARD
    );
    return $transliterator->transliterate($string);
}