Illegal character in Xml

I have a PHP file which produces an Xml sitemap based on data which has been imported from a number of sources开发者_C百科. My sitemap is currently not well formed due to an illegal character in one line of the imported data however I am struggling to remove it.

The character looks to represent the 'squared' or superscript 2, and is represented as a square. I have tried pasting this into a hex editor however it is shown as a ?, and the hex code also corresponds to ?. I have also tried using iconv to convert from all source encodings to all destination encodings, with no combination removing this character.

I also have the following function to remove non-ascii characters:

function stripInvalidXml($value)
{
    $ret = "";
    $current;
    if (empty($value)) 
    {
        return $ret;
    }

    $length = strlen($value);
    for ($i=0; $i < $length; $i++)
    {
        $current = ord($value{$i});
        if (($current == 0x9) ||
            ($current == 0xA) ||
            ($current == 0xD) ||
            (($current >= 0x20) && ($current <= 0xD7FF)) ||
            (($current >= 0xE000) && ($current <= 0xFFFD)) ||
            (($current >= 0x10000) && ($current <= 0x10FFFF)))
        {
            if($current != 0x1F)
            {
                $ret .= chr($current);
            }
        }
        else
        {
            $ret .= " ";
        }
    }


    return $ret;
}

However this still is not removing it. If I step through the code the illegal character is expanded out to ￿ in eclipses debug window. The string it is having issues with is below (hoping it pastes correctly)

251gm-50

Any ideas on a function which will remove this character and prevent this form occurring are much appreciated - I have little control over the data that is imported so it needs to be done at the point of Xml generation.

EDIT

After posting I can see that the character doesn't appear correctly. When viewing in Eclipses window it appears as & # 65535 ; (without spaces - if I leave spaces in it renders the character, which looks like ￿)

You are trying to perform character transcoding. Don't do it by yourself, use the PHP library.

I found iconv quite useful:

$cleanText = iconv('UTF-8','ISO-8859-1//TRANSLIT//IGNORE', $srcText);

This code translates from utf-8 to iso-8859, trying to remap the 'exotic' characters and ignoring the ones that can not be transcoded.

I'm just guessing the source encoding is utf-8. You have to discover which encoding the incoming data is using and translate in the one you are declaring in the XML header.

A linux command line tool that guesses a file's encoding is enca

This is wrong:

    $current = ord($value{$i});
    if (($current == 0x9) ||
        ($current == 0xA) ||
        ($current == 0xD) ||
        (($current >= 0x20) && ($current <= 0xD7FF)) ||
        (($current >= 0xE000) && ($current <= 0xFFFD)) ||
        (($current >= 0x10000) && ($current <= 0x10FFFF)))
    {
        if($current != 0x1F)
            $ret .= chr($current);
    }

ord() never returns anything bigger than 0xFF since it works in a byte-by-byte manner.

I'm guessing your XML is invalid because the file contains an invalid UTF-8 sequence (indeed , i.e., 0xFFFF, is invalid in UTF-8). This probably comes from copy-paste of different XML files that have different encodings.

I suggest you use the DOM extension instead to do your XML mash-up, which handles different encodings automatically by converting them internally to UTF-8.

I think I was looking down the wrong path - rather than an encoding issue character was an HTML entity representing the 'squared' symbol. As the descriptions in the URL only exist for search enging purposes I can safely remove all htmlentities with the following regex:

$content = preg_replace("/&#?[a-z0-9]+;/i","",$content);