Detect encoding and make everything UTF-8


Question

I'm reading out lots of texts from various RSS feeds and inserting them into my database.

Of course, there are several different character encodings used in the feeds, e.g. UTF-8 and ISO 8859-1.

Unfortunately, there are sometimes problems with the encodings of the texts. Example:

  1. The "ß" in "Fußball" should look like this in my database: "Ÿ". If it is a "Ÿ", it is displayed correctly.

  2. Sometimes, the "ß" in "Fußball" looks like this in my database: "ß". Then it is displayed wrongly, of course.

  3. In other cases, the "ß" is saved as a "ß" - so without any change. Then it is also displayed wrongly.

What can I do to avoid the cases 2 and 3?

How can I make everything the same encoding, preferably UTF-8? When must I use utf8_encode(), when must I use utf8_decode() (it's clear what the effect is but when must I use the functions?) and when must I do nothing with the input?

How do I make everything the same encoding? Perhaps with the function mb_detect_encoding()? Can I write a function for this? So my problems are:

  1. How do I find out what encoding the text uses?
  2. How do I convert it to UTF-8 - whatever the old encoding is?

Would a function like this work?

function correct_encoding($text) {
    $current_encoding = mb_detect_encoding($text, 'auto');
    $text = iconv($current_encoding, 'UTF-8', $text);
    return $text;
}

I've tested it, but it doesn't work. What's wrong with it?

1
287
7/8/2019 4:28:53 PM

Accepted Answer

If you apply utf8_encode() to an already UTF-8 string, it will return garbled UTF-8 output.

I made a function that addresses all this issues. It´s called Encoding::toUTF8().

You don't need to know what the encoding of your strings is. It can be Latin1 (ISO 8859-1), Windows-1252 or UTF-8, or the string can have a mix of them. Encoding::toUTF8() will convert everything to UTF-8.

I did it because a service was giving me a feed of data all messed up, mixing UTF-8 and Latin1 in the same string.

Usage:

require_once('Encoding.php');
use \ForceUTF8\Encoding;  // It's namespaced now.

$utf8_string = Encoding::toUTF8($utf8_or_latin1_or_mixed_string);

$latin1_string = Encoding::toLatin1($utf8_or_latin1_or_mixed_string);

Download:

https://github.com/neitanod/forceutf8

I've included another function, Encoding::fixUFT8(), which will fix every UTF-8 string that looks garbled.

Usage:

require_once('Encoding.php');
use \ForceUTF8\Encoding;  // It's namespaced now.

$utf8_string = Encoding::fixUTF8($garbled_utf8_string);

Examples:

echo Encoding::fixUTF8("Fédération Camerounaise de Football");
echo Encoding::fixUTF8("Fédération Camerounaise de Football");
echo Encoding::fixUTF8("FÃÂédÃÂération Camerounaise de Football");
echo Encoding::fixUTF8("Fédération Camerounaise de Football");

will output:

Fédération Camerounaise de Football
Fédération Camerounaise de Football
Fédération Camerounaise de Football
Fédération Camerounaise de Football

I've transformed the function (forceUTF8) into a family of static functions on a class called Encoding. The new function is Encoding::toUTF8().

343
7/8/2019 11:10:31 AM

You first have to detect what encoding has been used. As you’re parsing RSS feeds (probably via HTTP), you should read the encoding from the charset parameter of the Content-Type HTTP header field. If it is not present, read the encoding from the encoding attribute of the XML processing instruction. If that’s missing too, use UTF-8 as defined in the specification.


Edit   Here is what I probably would do:

I’d use cURL to send and fetch the response. That allows you to set specific header fields and fetch the response header as well. After fetching the response, you have to parse the HTTP response and split it into header and body. The header should then contain the Content-Type header field that contains the MIME type and (hopefully) the charset parameter with the encoding/charset too. If not, we’ll analyse the XML PI for the presence of the encoding attribute and get the encoding from there. If that’s also missing, the XML specs define to use UTF-8 as encoding.

$url = 'http://www.lr-online.de/storage/rss/rss/sport.xml';

$accept = array(
    'type' => array('application/rss+xml', 'application/xml', 'application/rdf+xml', 'text/xml'),
    'charset' => array_diff(mb_list_encodings(), array('pass', 'auto', 'wchar', 'byte2be', 'byte2le', 'byte4be', 'byte4le', 'BASE64', 'UUENCODE', 'HTML-ENTITIES', 'Quoted-Printable', '7bit', '8bit'))
);
$header = array(
    'Accept: '.implode(', ', $accept['type']),
    'Accept-Charset: '.implode(', ', $accept['charset']),
);
$encoding = null;
$curl = curl_init($url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_HEADER, true);
curl_setopt($curl, CURLOPT_HTTPHEADER, $header);
$response = curl_exec($curl);
if (!$response) {
    // error fetching the response
} else {
    $offset = strpos($response, "\r\n\r\n");
    $header = substr($response, 0, $offset);
    if (!$header || !preg_match('/^Content-Type:\s+([^;]+)(?:;\s*charset=(.*))?/im', $header, $match)) {
        // error parsing the response
    } else {
        if (!in_array(strtolower($match[1]), array_map('strtolower', $accept['type']))) {
            // type not accepted
        }
        $encoding = trim($match[2], '"\'');
    }
    if (!$encoding) {
        $body = substr($response, $offset + 4);
        if (preg_match('/^<\?xml\s+version=(?:"[^"]*"|\'[^\']*\')\s+encoding=("[^"]*"|\'[^\']*\')/s', $body, $match)) {
            $encoding = trim($match[1], '"\'');
        }
    }
    if (!$encoding) {
        $encoding = 'utf-8';
    } else {
        if (!in_array($encoding, array_map('strtolower', $accept['charset']))) {
            // encoding not accepted
        }
        if ($encoding != 'utf-8') {
            $body = mb_convert_encoding($body, 'utf-8', $encoding);
        }
    }
    $simpleXML = simplexml_load_string($body, null, LIBXML_NOERROR);
    if (!$simpleXML) {
        // parse error
    } else {
        echo $simpleXML->asXML();
    }
}

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