php - 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 "?" in "Fu?ball" should look like this in my database: "??". If it is a "??", it is displayed correctly.

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

3. In other cases, the "?" is saved as a "?" - 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?

Answer 1

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 ForceUTF8Encoding;  // 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 ForceUTF8Encoding;  // It's namespaced now.

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

Examples:

echo Encoding::fixUTF8("F??d??ration Camerounaise de Football");
echo Encoding::fixUTF8("F???d???ration Camerounaise de Football");
echo Encoding::fixUTF8("F?????d?????ration Camerounaise de Football");
echo Encoding::fixUTF8("F???dération 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().