As far as I know java uses UTF-16 to represent chars and string internally,
so if we load a text file from a file it is automatically decoded to its original encoding to utf-16.
Now the same can be said also for javascript
it also uses utf-16 as the internal string representation.
Suppose we load a string x encoded in utf-8 using ajax,
a converion takes place in order for javascript to be able to represent internally that string in UTF-16.
Please tell me if any of what I stated is correct or not,
because the real question is yet to come...
Now suppose the browser is rendering a page using utf-8 encoding,
and using javascript we want the browser to render also the ajax string x (as you normally do)
Would, in this case, a further conversion be needed from utf-16 to utf-8 ?
Thanks in advance.
According to this article, it is USC-2 or UTF-16
I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.
Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?
This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.
Data Storage:
Specify the utf8mb4 character set on all tables and text columns in your database. This makes MySQL physically store and retrieve values encoded natively in UTF-8. Note that MySQL will implicitly use utf8mb4 encoding if a utf8mb4_* collation is specified (without any explicit character set).
In older versions of MySQL (< 5.5.3), you'll unfortunately be forced to use simply utf8, which only supports a subset of Unicode characters. I wish I were kidding.
Data Access:
In your application code (e.g. PHP), in whatever DB access method you use, you'll need to set the connection charset to utf8mb4. This way, MySQL does no conversion from its native UTF-8 when it hands data off to your application and vice versa.
Some drivers provide their own mechanism for configuring the connection character set, which both updates its own internal state and informs MySQL of the encoding to be used on the connection—this is usually the preferred approach. In PHP:
If you're using the PDO abstraction layer with PHP ≥ 5.3.6, you can specify charset in the DSN:
$dbh = new PDO('mysql:charset=utf8mb4');
If you're using mysqli, you can call set_charset():
$mysqli->set_charset('utf8mb4'); // object oriented style
mysqli_set_charset($link, 'utf8mb4'); // procedural style
If you're stuck with plain mysql but happen to be running PHP ≥ 5.2.3, you can call mysql_set_charset.
If the driver does not provide its own mechanism for setting the connection character set, you may have to issue a query to tell MySQL how your application expects data on the connection to be encoded: SET NAMES 'utf8mb4'.
The same consideration regarding utf8mb4/utf8 applies as above.
Output:
UTF-8 should be set in the HTTP header, such as Content-Type: text/html; charset=utf-8. You can achieve that either by setting default_charset in php.ini (preferred), or manually using header() function.
If your application transmits text to other systems, they will also need to be informed of the character encoding. With web applications, the browser must be informed of the encoding in which data is sent (through HTTP response headers or HTML metadata).
When encoding the output using json_encode(), add JSON_UNESCAPED_UNICODE as a second parameter.
Input:
Browsers will submit data in the character set specified for the document, hence nothing particular has to be done on the input.
In case you have doubts about request encoding (in case it could be tampered with), you may verify every received string as being valid UTF-8 before you try to store it or use it anywhere. PHP's mb_check_encoding() does the trick, but you have to use it religiously. There's really no way around this, as malicious clients can submit data in whatever encoding they want, and I haven't found a trick to get PHP to do this for you reliably.
Other Code Considerations:
Obviously enough, all files you'll be serving (PHP, HTML, JavaScript, etc.) should be encoded in valid UTF-8.
You need to make sure that every time you process a UTF-8 string, you do so safely. This is, unfortunately, the hard part. You'll probably want to make extensive use of PHP's mbstring extension.
PHP's built-in string operations are not by default UTF-8 safe. There are some things you can safely do with normal PHP string operations (like concatenation), but for most things you should use the equivalent mbstring function.
To know what you're doing (read: not mess it up), you really need to know UTF-8 and how it works on the lowest possible level. Check out any of the links from utf8.com for some good resources to learn everything you need to know.
I'd like to add one thing to chazomaticus' excellent answer:
Don't forget the META tag either (like this, or the HTML4 or XHTML version of it):
<meta charset="utf-8">
That seems trivial, but IE7 has given me problems with that before.
I was doing everything right; the database, database connection and Content-Type HTTP header were all set to UTF-8, and it worked fine in all other browsers, but Internet Explorer still insisted on using the "Western European" encoding.
It turned out the page was missing the META tag. Adding that solved the problem.
Edit:
The W3C actually has a rather large section dedicated to I18N. They have a number of articles related to this issue – describing the HTTP, (X)HTML and CSS side of things:
FAQ: Changing (X)HTML page encoding to UTF-8
Declaring character encodings in HTML
Tutorial: Character sets & encodings in XHTML, HTML and CSS
Setting the HTTP charset parameter
They recommend using both the HTTP header and HTML meta tag (or XML declaration in case of XHTML served as XML).
In addition to setting default_charset in php.ini, you can send the correct charset using header() from within your code, before any output:
header('Content-Type: text/html; charset=utf-8');
Working with Unicode in PHP is easy as long as you realize that most of the string functions don't work with Unicode, and some might mangle strings completely. PHP considers "characters" to be 1 byte long. Sometimes this is okay (for example, explode() only looks for a byte sequence and uses it as a separator -- so it doesn't matter what actual characters you look for). But other times, when the function is actually designed to work on characters, PHP has no idea that your text has multi-byte characters that are found with Unicode.
A good library to check into is phputf8. This rewrites all of the "bad" functions so you can safely work on UTF8 strings. There are extensions like the mb_string extension that try to do this for you, too, but I prefer using the library because it's more portable (but I write mass-market products, so that's important for me). But phputf8 can use mb_string behind the scenes, anyway, to increase performance.
Warning: This answer applies to PHP 5.3.5 and lower. Do not use it for PHP version 5.3.6 (released in March 2011) or later.
Compare with Palec's answer to PDO + MySQL and broken UTF-8 encoding.
I found an issue with someone using PDO and the answer was to use this for the PDO connection string:
$pdo = new PDO(
'mysql:host=mysql.example.com;dbname=example_db',
"username",
"password",
array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));
In my case, I was using mb_split, which uses regular expressions. Therefore I also had to manually make sure the regular expression encoding was UTF-8 by doing mb_regex_encoding('UTF-8');
As a side note, I also discovered by running mb_internal_encoding() that the internal encoding wasn't UTF-8, and I changed that by running mb_internal_encoding("UTF-8");.
First of all, if you are in PHP before 5.3 then no. You've got a ton of problems to tackle.
I am surprised that none has mentioned the intl library, the one that has good support for Unicode, graphemes, string operations, localisation and many more, see below.
I will quote some information about Unicode support in PHP by Elizabeth Smith's slides at PHPBenelux'14
INTL
Good:
Wrapper around ICU library
Standardised locales, set locale per script
Number formatting
Currency formatting
Message formatting (replaces gettext)
Calendars, dates, time zone and time
Transliterator
Spoofchecker
Resource bundles
Convertors
IDN support
Graphemes
Collation
Iterators
Bad:
Does not support zend_multibyte
Does not support HTTP input output conversion
Does not support function overloading
mb_string
Enables zend_multibyte support
Supports transparent HTTP in/out encoding
Provides some wrappers for functionality such as strtoupper
ICONV
Primary for charset conversion
Output buffer handler
mime encoding functionality
conversion
some string helpers (len, substr, strpos, strrpos)
Stream Filter stream_filter_append($fp, 'convert.iconv.ISO-2022-JP/EUC-JP')
DATABASES
MySQL: Charset and collation on tables and on the connection (not the collation). Also, don't use mysql - mysqli or PDO
postgresql: pg_set_client_encoding
sqlite(3): Make sure it was compiled with Unicode and intl support
Some other gotchas
You cannot use Unicode filenames with PHP and windows unless you use a 3rd part extension.
Send everything in ASCII if you are using exec, proc_open and other command line calls
Plain text is not plain text, files have encodings
You can convert files on the fly with the iconv filter
The only thing I would add to these amazing answers is to emphasize on saving your files in UTF-8 encoding, I have noticed that browsers accept this property over setting UTF-8 as your code encoding. Any decent text editor will show you this. For example, Notepad++ has a menu option for file encoding, and it shows you the current encoding and enables you to change it. For all my PHP files I use UTF-8 without a BOM.
Sometime ago I had someone ask me to add UTF-8 support for a PHP and MySQL application designed by someone else. I noticed that all files were encoded in ANSI, so I had to use iconv to convert all files, change the database tables to use the UTF-8 character set and utf8_general_ci collate, add 'SET NAMES utf8' to the database abstraction layer after the connection (if using 5.3.6 or earlier. Otherwise, you have to use charset=utf8 in the connection string) and change string functions to use the PHP multibyte string functions equivalent.
I recently discovered that using strtolower() can cause issues where the data is truncated after a special character.
The solution was to use
mb_strtolower($string, 'UTF-8');
mb_ uses MultiByte. It supports more characters but in general is a little slower.
In PHP, you'll need to either use the multibyte functions, or turn on mbstring.func_overload. That way things like strlen will work if you have characters that take more than one byte.
You'll also need to identify the character set of your responses. You can either use AddDefaultCharset, as above, or write PHP code that returns the header. (Or you can add a META tag to your HTML documents.)
I have just gone through the same issue and found a good solution at PHP manuals.
I changed all my files' encoding to UTF8 and then the default encoding on my connection. This solved all the problems.
if (!$mysqli->set_charset("utf8")) {
printf("Error loading character set utf8: %s\n", $mysqli->error);
} else {
printf("Current character set: %s\n", $mysqli->character_set_name());
}
View Source
Unicode support in PHP is still a huge mess. While it's capable of converting an ISO 8859 string (which it uses internally) to UTF-8, it lacks the capability to work with Unicode strings natively, which means all the string processing functions will mangle and corrupt your strings.
So you have to either use a separate library for proper UTF-8 support, or rewrite all the string handling functions yourself.
The easy part is just specifying the charset in HTTP headers and in the database and such, but none of that matters if your PHP code doesn't output valid UTF-8. That's the hard part, and PHP gives you virtually no help there. (I think PHP 6 is supposed to fix the worst of this, but that's still a while away.)
If you want a MySQL server to decide the character set, and not PHP as a client (old behaviour; preferred, in my opinion), try adding skip-character-set-client-handshake to your my.cnf, under [mysqld], and restart mysql.
This may cause trouble in case you're using anything other than UTF-8.
The top answer is excellent. Here is what I had to on a regular Debian, PHP, and MySQL setup:
// Storage
// Debian. Apparently already UTF-8
// Retrieval
// The MySQL database was stored in UTF-8,
// but apparently PHP was requesting ISO 8859-1. This worked:
// ***notice "utf8", without dash, this is a MySQL encoding***
mysql_set_charset('utf8');
// Delivery
// File *php.ini* did not have a default charset,
// (it was commented out, shared host) and
// no HTTP encoding was specified in the Apache headers.
// This made Apache send out a UTF-8 header
// (and perhaps made PHP actually send out UTF-8)
// ***notice "utf-8", with dash, this is a php encoding***
ini_set('default_charset','utf-8');
// Submission
// This worked in all major browsers once Apache
// was sending out the UTF-8 header. I didn’t add
// the accept-charset attribute.
// Processing
// Changed a few commands in PHP, like substr(),
// to mb_substr()
That was all!
I am starting to create a Samsung TV App, which runs a pretty tight system where I can barely work with more than JS and HTML5. Furthermore, I have to send a json request to my web server to get the data down to the emulator client. For easier representation of my data I wanted to covert the json into XML. But due to having utf-8 encoded data on the web, it seems impossible for me to automate the decoding from json and encoding into XML.
Not like in some of the posts and aritcles I read, the json_encode creates HTML entities except of representations as something like \uXXXXXX.
So, what can I do?
the json_encode creates HTML entities
No, it doesn't.
except of representations as something like \uXXXXXX.
Those are JSON unicode escapes
So, what can I do?
Parse the JSON as normal. Generate the XML as normal.
Any JSON library and any XML library should be able to handle unicode characters.
I'd like to deliver custom binary data to browser. They are actually images, but I need to deliver multiple versions of the same image + some metadata. Network performance should be achieved by using just a single GET request, and it should unpack fast in the browser. So far I could think of these solutions:
image sprite (what about the metadata?)
ZIP
msgpack
JSON + base64 encoding
I don't care about < IE8. I think avoiding XHR is not possible in my case, but same origin policy is making it even worse as I need to load from different (sub) domain. That could be worked around though by server routing, on the other side that prevents using CDN.
That depend on data structure, but if you need do something with this data in JavaScript - there are two (three) ways to achieve this
JSON + base64 or escaping special characters
XML + base64 or escaping ( Choosing between one of them depend on preferences )
Harder one, but most effective - plain text with escaped 0 char and special marks (make three special codes - 0x20 0x40 for 0x00 char, 0x20 0x41 as mark and 0x20 0x42 for 0x20)
It turned out today's (and near future - IE9) browsers have very poor support for binary data, so whatever you decide to use, it has to be encoded (encodeable?) into a Javascript String, ie. JSON+base64.
For curious minds: http://status-501.tumblr.com/post/20293218962/delivering-binary-data-to-browser
what the built-in or user-defined function that I can use in Javascript or jQuery to convert from one character encoding to another?
For Example,
FROM "utf-8" TO "windows-1256"
OR
FROM "windows-1256" TO "utf-8"
A practical use of that is if you have a php page with specific character encoding like "windows-1256" that you could not change it according to the business needs and when you use ajax to send a block data from database using json which uses "utf-8" encoding only so you need to convert the ouput of json to this encoding so that the characters and the strings will be displayed well
Thanks in advance .....
From the standpoint of a JavaScript runtime environment, there's really no such thing as character encodings – the messiness of encodings is abstracted away from you. By spec, all JS source text is interpreted as Unicode characters, and all Strings are Unicode.
As such, there's no way in JavaScript to represent characters in anything other than Unicode. Look at the methods available on a String instance – you'll see there's nothing related to character encoding.
Because JavaScript runs in Unicode, and all JavaScript strings are stored in Unicode, all AJAX calls will be transmitted over the wire in Unicode. From the jQuery AJAX docs:
Data will always be transmitted to the server using UTF-8 charset; you must decode this appropriately on the server side.
Your PHP script is going to have to cope with Unicode input from AJAX calls.