How to use php extension mbstring for multibyte string manipulation

How to use PHP extension mbstring for multi-byte string operations

Summary: When processing multi-byte strings, it is very important to use PHP's mbstring extension. This article describes how to use the mbstring extension for multi-byte string operations and provides relevant code examples.

Introduction: When processing multi-byte strings, we often encounter some problems, such as counting string lengths, intercepting substrings of specific lengths, converting character encodings, etc. These problems can be solved by using PHP's mbstring extension. The mbstring extension is a tool for processing multi-byte characters, providing a number of functions and methods for string operations.

1. Enable the mbstring extension
To use the mbstring extension, you first need to enable the extension in the php.ini file. Please open the php.ini file and find the following line (it may be different according to different PHP versions):

;extension=mbstring.so
Remove the semicolon (;) at the beginning of the line, and save document. Then restart the web server for the settings to take effect.

2. Obtain the length of a multi-byte string
When processing multi-byte strings, it is often necessary to obtain the length of the string. The commonly used strlen() function only applies to single-byte strings, and inaccurate results will occur for multi-byte strings. The mbstring extension provides a mb_strlen() function for getting the length of a multi-byte string.

The following is an example:

$str = '你好，世界！';
$length = mb_strlen($str, 'UTF-8');
echo $length; // 输出：7

In the above example, we obtain the length of the $str string through the mb_strlen() function, where the second parameter specifies the character encoding as UTF -8.

3. Intercepting multi-byte strings
Sometimes, when displaying multi-byte strings, it is necessary to limit the length of the string. The commonly used substr() function is only applicable to single-byte strings, and will also produce inaccurate results for multi-byte strings. The mbstring extension provides a mb_substr() function for intercepting multi-byte strings.

The following is an example:

$str = '你好，世界！';
$subStr = mb_substr($str, 0, 3, 'UTF-8');
echo $subStr; // 输出：你好，

In the above example, we use the mb_substr() function to intercept the first 3 characters of the $str string, and the first parameter is to intercept string, the second parameter is the starting position, the third parameter is the intercepted length, and the fourth parameter is the character encoding.

4. Convert character encoding
In multi-byte string processing, sometimes it is necessary to convert character encoding. We can use the mb_convert_encoding() function provided by the mbstring extension to achieve this.

The following is an example:

$str = '你好，世界！';
$newStr = mb_convert_encoding($str, 'GBK', 'UTF-8');
echo $newStr; // 输出：鍏ㄩ儴锛丂C码鍘熷�！

In the above example, we converted the $str string from UTF-8 encoding to GBK encoding and obtained the $newStr string.

Summary: Use PHP's mbstring extension to effectively handle multi-byte strings and provide some functions and methods for string operations. During the development process, when encountering problems related to multi-byte strings, we should consider using the mbstring extension to solve them. This article describes how to enable the mbstring extension and how to use the functions and methods it provides. Hope this article is helpful to you.

Reference:

• PHP official documentation: https://www.php.net/manual/zh/book.mbstring.php

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