PHP function introduction—mb_strlen(): Get the length of a multi-byte string

PHP function introduction—mb_strlen(): Get the length of a multi-byte string

In development, we often need to process multi-byte strings, such as Chinese, Japanese, etc., and traditional PHP functions Support for handling multi-byte strings is not good. Therefore, PHP provides the mb_strlen() function to get the length of a multi-byte string. In this article, we will introduce the usage of mb_strlen() function and provide some code examples.

The mb_strlen() function is defined in the mbstring extension, so before using it, we need to ensure that the mbstring extension has been installed and enabled. You can enable the extension by removing the relevant comments in the php.ini file, or use the phpinfo() function to view the current PHP configuration information to confirm whether it is enabled.

The syntax of the mb_strlen() function is as follows:
int mb_strlen ( string $str [, string $encoding = mb_internal_encoding() ] )

Among them, the parameter $str needs to calculate the length Multi-byte string, parameter $encoding is optional, used to specify the character encoding of the string. If the $encoding parameter is not specified, the character encoding returned by the mb_internal_encoding() function is used by default.

The following is a simple example, we will use the mb_strlen() function to calculate the length of a Chinese string:
$str = "Hello, world!";
echo mb_strlen($str); // Output: 7
?>

In the above example, use the mb_strlen() function to calculate the length of the $str string and output the result. Because the $str string contains 4 Chinese characters and 3 English characters, the final output result is 7.

The mb_strlen() function can also specify the character encoding when processing strings with different encodings. The following example is a string encoded in UTF-8:
$str = "こんにちは世界";
echo mb_strlen($str, "UTF-8"); // Output :6
?>

In the above example, the character encoding is specified as UTF-8, and the mb_strlen() function is used to calculate the length of the UTF-8 string. Because the $str string contains 3 Japanese characters and 3 Chinese characters, the final output result is 6.

In addition to obtaining the length of a multi-byte string, the mb_strlen() function can also be used to verify whether the length of the string meets the requirements. For example, we can limit the length of a string to a certain value. Here is an example:
$str = "This is a very long sentence.";
$max_length = 20;
if (mb_strlen($str) > $max_length ) {

echo "String is too long.";

} else {

echo "String is within the limit.";

}
?>

In the above example, we set the maximum length of a string to 20 character. If the length of the $str string exceeds this limit, "String is too long." is output, otherwise "String is within the limit." is output.

Through the above examples, we have learned the basic usage of the mb_strlen() function and some common application scenarios. In actual development, when encountering the problem of processing multi-byte strings, the mb_strlen() function can help us process it more conveniently.

Summary:
mb_strlen() function is a function in PHP used to obtain the length of a multi-byte string. By specifying the character encoding, we can flexibly handle strings with different encodings. During development, we can use the mb_strlen() function to obtain the length of the string and perform length verification and other operations. With the support of this function, we can better handle multi-byte strings and improve the accuracy and stability of the program.

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