UTF-8 at the PHP and Database level

UTF-8 at PHP Level:

Must use the mb_* functions (such as mb_strpos() and mb_strlen() ) whenever operate on Unicode string. For example you use substr() on a UTF-8 string, there's a good chance the result will include some garbled half-characters.

Not all string functions have an mb_* counterpart, in this case, should use the mb_internal_encoding() function at the top of every PHP script (or at the top of your global include script), and mb_http_output() function right after it if script is outputting to a browser.

Many PHP functions that operate on strings have an optional parameter letting you specify the character encoding. 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:

Make sure strings go from PHP to MySQL as UTF-8, make sure 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.

Note: Must use the utf8mb4 character set for complete UTF-8 support, not the utf8 character set!

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.

The browser will then need to be told by the HTTP response that this page should be considered as UTF-8. Today, it is common to set the character set in the HTTP response header like this:

<?php

header('Content-Type: text/html; charset=UTF-8');

<?php
// Tell PHP that we're using UTF-8 strings until the end of the script
mb_internal_encoding('UTF-8');
$utf_set = ini_set('default_charset', 'utf-8');
if (!$utf_set) {
    throw new Exception('could not set default_charset to utf-8, please ensure it\'s set on your system!');
}

// Tell PHP that we'll be outputting UTF-8 to the browser
mb_http_output('UTF-8');
 
// Our UTF-8 test string
$string = 'Êl síla erin lû e-govaned vîn.';

// Transform the string in some way with a multibyte function
// Note how we cut the string at a non-Ascii character for demonstration purposes
$string = mb_substr($string, 0, 15);

// Connect to a database to store the transformed string
// See the PDO example in this document for more information
// Note the `charset=utf8mb4` in the Data Source Name (DSN)
$link = new PDO(
    'mysql:host=your-hostname;dbname=your-db;charset=utf8mb4',
    'your-username',
    'your-password',
    array(
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
        PDO::ATTR_PERSISTENT => false
    )
);

// Store our transformed string as UTF-8 in our database
// Your DB and tables are in the utf8mb4 character set and collation, right?
$handle = $link->prepare('insert into ElvishSentences (Id, Body, Priority) values (default, :body, :priority)');
$handle->bindParam(':body', $string, PDO::PARAM_STR);
$priority = 45;
$handle->bindParam(':priority', $priority, PDO::PARAM_INT); // explicitly tell pdo to expect an int
$handle->execute();

// Retrieve the string we just stored to prove it was stored correctly
$handle = $link->prepare('select * from ElvishSentences where Id = :id');
$id = 7;
$handle->bindParam(':id', $id, PDO::PARAM_INT);
$handle->execute();

// Store the result into an object that we'll output later in our HTML
// This object won't kill your memory because it fetches the data Just-In-Time to
$result = $handle->fetchAll(\PDO::FETCH_OBJ);

// An example wrapper to allow you to escape data to html
function escape_to_html($dirty){
    echo htmlspecialchars($dirty, ENT_QUOTES, 'UTF-8');
}

header('Content-Type: text/html; charset=UTF-8'); // Unnecessary if your default_charset is set to utf-8 already
?><!doctype html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>UTF-8 test page</title>
    </head>
    <body>
        <?php
        foreach($result as $row){
            escape_to_html($row->Body);  // This should correctly output our transformed UTF-8 string to the browser
        }
        ?>
    </body>
</html>

UTF-8 at the PHP and Database level

Guess you like