php convert data to utf 8

In the daily development process, we often encounter character encoding problems, especially when multiple languages ​​are involved. As a commonly used development language, PHP must have the correct character encoding processing method, otherwise it will cause garbled characters in the application system and affect the user experience.

This article will introduce how PHP converts data in different encoding formats into UTF-8 encoding, so that everyone can quickly solve this common problem.

1. What is UTF-8 encoding?

UTF-8 is a variable-length character encoding for Unicode and one of the most commonly used character encodings at present. It supports all Unicode characters, including Asian characters and European characters, so it is widely used in web browsers, emails, operating systems and other application systems.

In UTF-8 encoding, one character can occupy 1 to 4 bytes. Among them, ASCII characters (i.e. English, numbers, punctuation marks) occupy 1 byte, and Chinese characters occupy 3 bytes. The advantage of this encoding method is that it is backward compatible with the ASCII character set, so that we can ensure that the previous ASCII data can be displayed normally under the new encoding format. At the same time, because UTF-8 encodes and decodes data in bytes, it supports random access to text and improves the efficiency of data storage, transmission and processing.

2. Character encoding issues in PHP

For a website application, the diversity of data sources will affect the diversity of character encoding. We need to correctly handle different encodings in the code to ensure the normal operation of the application. For example, the data in the database may be GBK encoded; the data input by the user may be UTF-8 encoded; the data uploaded by the file may be ISO-8859-1 encoded; the data output to the front end may be GB2312 encoded, etc.

If you mix data of different encodings directly in the application, garbled characters will appear, which is very unfriendly to the user experience.

3. PHP converts data to UTF-8 encoding

1. Convert source data encoding

First, we need to find the source of the data, that is, obtain The encoding format of the data.

For example, the data in the database often uses GBK encoding, and we need to convert it to UTF-8 encoding when we obtain the data. PHP's mysql extension provides the mysql_set_charset method, which can change the MySQL database character set connection.

$conn = mysql_connect('localhost', 'mysql_user', 'mysql_password');
mysql_set_charset('utf8', $conn);
mysql_select_db('mydb', $conn);

2. Convert user input data encoding

Users may enter data containing special characters in forms, input boxes, etc., such as special symbols, Chinese, Korean, Japanese, etc. wait. This data will be passed to the server in the form of post or get. If the encoding of the data is not UTF-8, we need to convert it to UTF-8 encoding.

It is recommended to use the mb_convert_encoding method to convert the encoding:

$request = array_merge($_GET, $_POST);
foreach ($request as $key => &$value) {
    if (!is_array($value)) {
        $value = mb_convert_encoding($value, 'UTF-8', 'GBK');
    }
}
unset($value);

3. Convert file upload data encoding

For file upload data, we may need to convert the encoding format . For example, when uploading an MS Office file, since the file itself may use ISO-8859-1 encoding, we need to convert it to UTF-8 encoding to avoid garbled characters.

if (isset($_FILES['file'])) {
    $file = $_FILES['file'];
    $tmpfilePath = $file['tmp_name'];
    $tmpfile = file_get_contents($tmpfilePath);
    $tmpfile = mb_convert_encoding($tmpfile, 'UTF-8', 'ISO-8859-1');
    file_put_contents($tmpfilePath, $tmpfile);
}

4. Convert encoding when outputting data

When we output data to the front end, we need to convert the encoding format into the encoding format required by the front end, which is usually UTF-8 encoding. We can use the iconv function to implement encoding conversion. Commonly used parameters include specifying the character encoding, input string, and output string.

header('Content-Type: application/xml; charset=utf-8');
echo iconv('GBK', 'UTF-8', $xml);

In this example, the iconv function is used to convert a GBK-encoded XML format string into UTF-8 encoding, and then the XML string is output to the front end.

4. Avoid encoding problems

The above content mentioned the character encoding conversion processing in PHP. In fact, we can avoid character encoding problems in the following two ways:

1. Uniform Character Encoding

We can convert all data into UTF-8 encoding format, thus avoiding the problem of character encoding conversion between different data. The implementation is usually as follows: in the data acquisition and processing layer, data is stored and processed in UTF-8 mode. For example, when the front end uses JS or jQuery to obtain data, it is initialized using UTF8 encoding, and the back end uses UTF-8 encoding to store and operate.

2. Set character encoding

Set the character encoding for various input/output methods in the code, such as setting the encoding method of MySQL, the character encoding method of PHP, and the HTML page encoding method, etc. Ensure that all kinds of data are correctly encoded to avoid garbled characters.

Summary:

This article details how PHP converts data in different encoding formats to UTF-8 encoding, and provides code examples in various aspects to help us understand, which is suitable for multi-language applications. Development is very important. At the same time, we also introduced two methods to avoid encoding problems, which greatly reduced the trouble of encoding processing problems.

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