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added PHP and UTF-8 section
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Yannick Lyn Fatt
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_posts/05-05-01-PHP-and-UTF8.md
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_posts/05-05-01-PHP-and-UTF8.md
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## PHP and UTF-8 {#php_and_utf8_title}
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_This section was originally written by [Alex Cabal](https://alexcabal.com/) over at [PHP Best Practices](https://phpbestpractices.org/#utf-8) and has now been shared here_.
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### There's no one-liner. Be careful, detailed, and consistent.
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UTF-8 in PHP sucks. Sorry.
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Right now PHP does not support Unicode at a low level. There are ways to ensure that UTF-8 strings are processed OK, but it's not easy, and it requires digging in to almost all levels of the web app, from HTML to SQL to PHP. We'll aim for a brief, practical summary.
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### UTF-8 at the PHP level
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The basic [string operations](http://php.net/manual/en/language.operators.string.php), like concatenating two strings and assigning strings to variables, don't need anything special for UTF-8. However most [string functions](http://php.net/manual/en/ref.strings.php), like [`strpos()`](http://php.net/manual/en/function.strpos.php) and [`strlen()`](http://php.net/manual/en/function.strlen.php), do need special consideration. These functions often have an `mb_*` counterpart: for example, [`mb_strpos()`](http://php.net/manual/en/function.mb-strpos.php) and [`mb_strlen()`](http://php.net/manual/en/function.mb-strlen.php). Together, these counterpart functions are called the [Multibyte String Functions](http://php.net/manual/en/ref.mbstring.php). The multibyte string functions are specifically designed to operate on Unicode strings.
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You must use the `mb_*` functions whenever you operate on a Unicode string. For example, if you use [`substr()`](http://php.net/manual/en/function.substr.php) on a UTF-8 string, there's a good chance the result will include some garbled half-characters. The correct function to use would be the multibyte counterpart, [`mb_substr()`](http://php.net/manual/en/function.mb-substr.php).
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The hard part is remembering to use the `mb_*` functions at all times. If you forget even just once, your Unicode string has a chance of being garbled during further processing.
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Not all string functions have an `mb_*` counterpart. If there isn't one for what you want to do, then you might be out of luck.
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Additionally, you should use the [`mb_internal_encoding()`](http://php.net/manual/en/function.mb-internal-encoding.php) function at the top of every PHP script you write (or at the top of your global include script), and the [`mb_http_output()`](http://php.net/manual/en/function.mb-http-output.php) function right after it if your script is outputting to a browser. Explicitly defining the encoding of your strings in every script will save you a lot of headaches down the road.
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Finally, many PHP functions that operate on strings have an optional parameter letting you specify the character encoding. You should always explicitly indicate UTF-8 when given the option. For example, [`htmlentities()`](http://php.net/manual/en/function.htmlentities.php) has an option for character encoding, and you should always specify UTF-8 if dealing with such strings.
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### UTF-8 at the MySQL level
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If your PHP script accesses MySQL, there's a chance your strings could be stored as non-UTF-8 strings in the database even if you follow all of the precautions above.
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To make sure your strings go from PHP to MySQL as UTF-8, make sure your database and tables are all set to the utf8mb4 character set, and issue the MySQL query `set names utf8mb4` before issuing any other queries in your database. For an example, see the section on [connecting to and querying a MySQL database](https://phpbestpractices.org/#mysql). This is critically important.
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Note that you must use the `utf8mb4` character set for complete UTF-8 support, not the `utf8` character set! See Further Reading for why.
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### UTF-8 at the browser level
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Use the [`mb_http_output()`](http://php.net/manual/en/function.mb-http-output.php) function to ensure that your PHP script outputs UTF-8 strings to your browser. In your HTML, include the [charset `<meta>` tag](http://htmlpurifier.org/docs/enduser-utf8.html) in your page's `<head>` tag.
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{% highlight php %}
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<?php
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// Tell PHP that we're using UTF-8 strings until the end of the script
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mb_internal_encoding('UTF-8');
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// Tell PHP that we'll be outputting UTF-8 to the browser
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mb_http_output('UTF-8');
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// Our UTF-8 test string
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$string = 'Aš galiu valgyti stiklą ir jis manęs nežeidžia';
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// Transform the string in some way with a multibyte function
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$string = mb_substr($string, 0, 10);
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// Connect to a database to store the transformed string
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// See the PDO example in this document for more information
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// Note the `set names utf8mb4` commmand!
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$link = new \PDO( 'mysql:host=your-hostname;dbname=your-db',
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'your-username',
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'your-password',
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array(
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\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
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\PDO::ATTR_PERSISTENT => false,
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\PDO::MYSQL_ATTR_INIT_COMMAND => 'set names utf8mb4'
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)
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);
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// Store our transformed string as UTF-8 in our database
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// Assume our DB and tables are in the utf8mb4 character set and collation
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$handle = $link->prepare('insert into Sentences (Id, Body) values (?, ?)');
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$handle->bindValue(1, 1, PDO::PARAM_INT);
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$handle->bindValue(2, $string);
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$handle->execute();
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// Retrieve the string we just stored to prove it was stored correctly
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$handle = $link->prepare('select * from Sentences where Id = ?');
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$handle->bindValue(1, 1, PDO::PARAM_INT);
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$handle->execute();
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// Store the result into an object that we'll output later in our HTML
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$result = $handle->fetchAll(\PDO::FETCH_OBJ);
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?><!doctype html>
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>UTF-8 test page</title>
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</head>
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<body>
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<?php
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foreach($result as $row){
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print($row->Body); // This should correctly output our transformed UTF-8 string to the browser
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}
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?>
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</body>
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</html>
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{% endhighlight %}
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### Further reading
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* [PHP Manual: Multibyte String Functions](http://php.net/manual/en/ref.mbstring.php)
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* [PHP UTF-8 Cheatsheet](http://blog.loftdigital.com/blog/php-utf-8-cheatsheet)
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* [Stack Overflow: What factors make PHP Unicode-incompatible?](http://stackoverflow.com/questions/571694/what-factors-make-php-unicode-incompatible)
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* [Stack Overflow: Best practices in PHP and MySQL with international strings](http://stackoverflow.com/questions/140728/best-practices-in-php-and-mysql-with-international-strings)
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* [How to support full Unicode in MySQL databases](http://mathiasbynens.be/notes/mysql-utf8mb4)
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* [Brining Unicode to PHP with Portable UTF-8](http://www.sitepoint.com/bringing-unicode-to-php-with-portable-utf8/)
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