When using preg_replace I get double characters...?

When I use the following script, I get double characters. Why?

$clean_lastname = "Dür";
$clean_lastname = preg_replace("/[ùúûü]/", "u", $clean_lastname);
echo $clean_lastname;

Output: Duur

I want it to be Dur.

I am still doing something wrong... What's up with the 'putting one value of an array in the preg function?

$clean_lastname = "Boerée";
$l = 0;
$pattern = array('[ÀÁÂÃÄÅ]','[Ç]','[ÈÉÊË]','[ÌÍÎÏ]','[Ñ]','[ÒÓÔÕÖØ]','[Ý]','[ß]','[àáâãäå]','[ç]','[èéêë]','[ìíîï]','[ñ]','[òóôõöø]','[ùúûü]','[ýÿ]');
$replace = array(A,C,E,I,N,O,Y,S,a,c,e,i,n,o,u,y);

foreach ($pattern as $wierdchar)
{
    $clean_lastname = preg_replace('/$wierdchar/u', '$replace[$l]', $clean_lastname);
    $l++;
}

//$clean_lastname = preg_replace('/[èéêë]/u', 'e', $clean_lastname);

//$clean_l开发者_开发知识库astname = strtr($clean_lastname, "ùúûü","uuuu");
echo $clean_lastname;

$clean_lastname = str_replace(array('ù', 'ú', 'û', 'ü', 'Ù', 'Ú', 'Û', 'Ü'), array('u', 'u', 'u', 'u', 'U', 'U', 'U', 'U'), $clean_lastname);

// OR to solve your initial issue:

$clean_lastname = preg_replace('/[ùúûü]/u', 'u', $clean_lastname);

The only situation I can image this to happen is when your two strings (the input string and the pattern) have a different character encoding or both are UTF-8 but you didn’t specify it properly.

Because in the latter case, "Dür" is equivalent to "D\xC3\xBCr" (ü is encoded with the two byte sequence 0xC3BC) and the pattern "/[ùúûü]/" is equivalent to "/[\xC3\xB9\xC3\xBA\xC3\xBB\xC3\xBC]/". Since each byte specified by the escape sequence \xHH is treated as a single character, this yields the following result:

echo preg_replace("/[\xC3\xB9\xC3\xBA\xC3\xBB\xC3\xBC]/", "u", "D\xC3\xBCr");  // Duur

So when working with UTF-8 make sure to set the u modifier flag so that the pattern and input string is treated as UTF-8 encoded:

"/[ùúûü]/u"

Edit    Now that you clarified your intentions and you seem to try to implement some kind of transliteration, you should take a look at iconv and it’s ability to transliterate:

iconv("UTF-8", "US-ASCII//TRANSLIT", $str)

See also other related topics like:

• How to transliterate accented characters into plain ASCII characters?
• How to handle user input of invalid UTF-8 characters?

<?php
    $vowels = array("ù","ú","û","ü" );
    $consonents = array("u","u","u","u");
    $clean_lastname = "Dür";
    echo str_replace( $vowels, $consonents, $clean_lastname);
?>

stick with your original strtr

$clean_lastname = "Dür Dùr Dúr Dûr";
$clean_lastname = strtr($clean_lastname, "ùúûü", "uuuu");
echo $clean_lastname;