Calculate string length using mb_strlen() function in PHP

In PHP development, it is often necessary to calculate the length of a string. PHP provides a built-in function mb_strlen(), which is used to calculate the length of a string, especially suitable for processing Chinese characters.

In PHP, the length of a string can be obtained using the strlen() function. However, this function has problems with statistics on strings containing non-ASCII characters (including Chinese). Since strlen() is calculated based on the number of bytes occupied by each character, in some encoding methods, Chinese characters occupy 2 or 3 bytes, while ASCII characters only occupy 1 byte, so if the string contains Chinese characters, then the string length calculated by the strlen() function is inaccurate.

For example:

$str = 'Hello 你好';
echo strlen($str);

The output result is 11, but in fact the length of this string should be 8. This is because the number of bytes occupied by Chinese characters is different, resulting in inaccurate calculation of the strlen() function.

To solve this problem, we can use the mb_strlen() function.

The syntax of the mb_strlen() function is as follows:

int mb_strlen ( string $str [, string $encoding = mb_internal_encoding() ] )

Among them, $str is the string whose length needs to be calculated, $encoding is the encoding method of the string, and the default is the internal character encoding of the current script. . If the string is encoded using UTF-8, the $encoding parameter can be omitted or set to 'UTF-8'.

Using the mb_strlen() function, the above example can be rewritten as follows:

$str = 'Hello 你好';
echo mb_strlen($str, 'UTF-8');

At this time, the output result is 8, which is consistent with the actual length. The mb_strlen() function automatically identifies non-ASCII characters in the string, correctly calculates the number of bytes they occupy, and returns the actual length of the string.

It should be noted that the mb_strlen() function is only suitable for calculating the length of multi-byte character encoded strings. For calculating the length of single-byte encoded strings, you still need to use the strlen() function.

In addition to the mb_strlen() function, PHP also provides a series of functions starting with mb_ for processing multi-byte character encoding strings, such as mb_substr(), mb_strpos(), mb_strtolower(), etc. These functions are very useful when dealing with multi-language website development.

To summarize, using the mb_strlen() function in PHP to calculate the string length can correctly handle the length calculation of Chinese characters. This function is very useful for the development of multilingual websites.

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