How to treat Chinese characters and various special punctuation characters as 2 characters in length during UTF-8 Coding

This title is a bit of a second... I don't know how to describe it. Let's take a look. The maximum length of a registered user is 12 in Chinese and 24 in English. How can we verify this in PHP? The length of a Chinese character in strlen is 3 in UTF-8 encoding. Using mb_strl... is a bit of a title... I don't know how to describe it. Let's take a look.

The length limit that is frequently seen when registering users is:
You can enter 12 Chinese characters and 24 English letters.
How can we verify this in PHP?

UTF-8 Encoding
The length of a Chinese character using strlen is 3.
The length of a Chinese character using mb_strlen is 1.

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This title is a bit of a second... I don't know how to describe it. Let's take a look.

The length limit that is frequently seen when registering users is:
You can enter 12 Chinese characters and 24 English letters.
How can we verify this in PHP?

UTF-8 Encoding
The length of a Chinese character using strlen is 3.
The length of a Chinese character using mb_strlen is 1.

It seems that you do not know that there is a function named mb_strwidth.

The characters encoded by the UTF-8 may be 1 ~ It consists of three bytes. The specific number can be determined by the first byte. (Theoretically it may be longer, but it is assumed that the length cannot exceed 3 bytes)

Encoding method of UTF-8

1. The first byte is greater than 224, which together with the second byte after it forms a UTF-8 character
2. The first byte is greater than 192 less than 224, and it is a UTF-8 character with the first byte after it
3. Otherwise, the first byte is an English character (including numbers and a small part of punctuation marks ).

You can specify the encoding for obtaining the length:

mb_strlen($str,'gb2312')

It's easy. Convert the code to cp936, and then use strlen directly.