diff --git a/_posts/05-05-01-PHP-and-UTF8.md b/_posts/05-05-01-PHP-and-UTF8.md index e0bd47e..7c98c03 100644 --- a/_posts/05-05-01-PHP-and-UTF8.md +++ b/_posts/05-05-01-PHP-and-UTF8.md @@ -4,37 +4,61 @@ isChild: true ## PHP and UTF-8 {#php_and_utf8_title} -_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_. +_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_. ### There's no one-liner. Be careful, detailed, and consistent. -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. +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. ### UTF-8 at the PHP level -The basic string operations, like concatenating two strings and assigning strings to variables, don't need anything special for UTF-8. However most string functions, like `strpos()` and `strlen()`, do need special consideration. These functions often have an `mb_*` counterpart: for example, `mb_strpos()` and `mb_strlen()`. Together, these counterpart functions are called the Multibyte String Functions. The multibyte string functions are specifically designed to operate on Unicode strings. +The basic string operations, like concatenating two strings and assigning strings to variables, don't need anything +special for UTF-8. However most string functions, like `strpos()` and `strlen()`, do need special consideration. These +functions often have an `mb_*` counterpart: for example, `mb_strpos()` and `mb_strlen()`. Together, these counterpart +functions are called the Multibyte String Functions. The multibyte string functions are specifically designed to +operate on Unicode strings. -You must use the `mb_*` functions whenever you operate on a Unicode string. For example, if you use `substr()` 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()`. +You must use the `mb_*` functions whenever you operate on a Unicode string. For example, if you use `substr()` 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()`. -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. +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. -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. +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. -Additionally, you should use the `mb_internal_encoding()` function at the top of every PHP script you write (or at the top of your global include script), and the `mb_http_output()` 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. +Additionally, you should use the `mb_internal_encoding()` function at the top of every PHP script you write (or at the +top of your global include script), and the `mb_http_output()` 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. + +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()` has an +option for character encoding, and you should always specify UTF-8 if dealing with such strings. + +Note that as of PHP 5.4.0, UTF-8 is the default encoding for `htmlentities()` and `htmlspecialchars()`. -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()` has an option for character encoding, and you should always specify UTF-8 if dealing with such strings. ### UTF-8 at the Database level -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. +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. -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 collation, and that you use the `utf8mb4` character set in the PDO connection string. See example code below. This is _critically important_. +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 collation, and that you use the `utf8mb4` character set in the PDO connection string. See +example code below. This is _critically important_. -Note that you must use the `utf8mb4` character set for complete UTF-8 support, not the `utf8` character set! See Further Reading for why. +Note that you must use the `utf8mb4` character set for complete UTF-8 support, not the `utf8` character set! See +Further Reading for why. ### UTF-8 at the browser level -Use the `mb_http_output()` function to ensure that your PHP script outputs UTF-8 strings to your browser. In your HTML, include the [charset `` tag](http://htmlpurifier.org/docs/enduser-utf8.html) in your page's `` tag. +Use the `mb_http_output()` function to ensure that your PHP script outputs UTF-8 strings to your browser. In your HTML, +include the [charset `` tag](http://htmlpurifier.org/docs/enduser-utf8.html) in your page's `` tag. {% highlight php %} fetchAll(\PDO::FETCH_OBJ); * [`mb_internal_encoding()`](http://php.net/manual/en/function.mb-internal-encoding.php) * [`mb_http_output()`](http://php.net/manual/en/function.mb-http-output.php) * [`htmlentities()`](http://php.net/manual/en/function.htmlentities.php) + * [`htmlspecialchars()`](http://www.php.net/manual/en/function.htmlspecialchars.php) * [PHP UTF-8 Cheatsheet](http://blog.loftdigital.com/blog/php-utf-8-cheatsheet) * [Stack Overflow: What factors make PHP Unicode-incompatible?](http://stackoverflow.com/questions/571694/what-factors-make-php-unicode-incompatible) * [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)