How to calculate how many bytes a string occupies in php

In PHP, you can use the strlen() function to calculate the number of bytes in a string. This function calculates the length of a string in bytes and can count the character length (number of bytes) occupied by the string. The syntax is "strlen (string)". In the calculation of this function, English commas, numbers, English letters, decimal points, etc. only occupy one byte; while a GB2312-encoded Chinese character occupies two bytes, and a UTF-8-encoded Chinese character occupies three bytes.

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, DELL G3 computer

Characters occupied by different encoding formats in php The bytes are different:

• In the ANSI encoding format, one Chinese character occupies 2 bytes and one English character occupies 1 byte;

• UTF-8 encoding format: One Chinese character occupies 3 bytes, and one English character occupies 1 byte.

#In PHP, you can use the strlen() function to calculate the number of bytes in a string.

The strlen() function calculates the length of a string in bytes.

strlen($string)

This function only accepts one parameter $string (the string to be calculated), and returns 0 if the value passed in this parameter is empty.

In the strlen() function, (in English mode) commas, numbers, English letters, decimal points ., underscores, spaces, etc. only occupy one character in length ( byte).

<?php
header("Content-type:text/html;charset=utf-8");
$str = "hello world!";
echo &#39;字符串 “&#39;.$str.&#39;” 占：&#39;.strlen($str).&#39; 个字节<br>&#39;;
?>

Analysis: In the string in the above example, there are 10 English letters, a space, and an English exclamation mark; total: 12 bytes.

In the strlen() function, a GB2312-encoded Chinese character occupies two characters in length (bytes), and a UTF-8-encoded Chinese character occupies three characters in length (bytes).

<?php
header("Content-type:text/html;charset=utf-8");
$str = "！";
echo &#39;字符串 “&#39;.$str.&#39;” 占：&#39;.strlen($str).&#39; 个字节<br>&#39;;
?>

In the above example, "!" is a Chinese exclamation mark, so it occupies three bytes.

<?php
header("Content-type:text/html;charset=utf-8");
$str = "欢迎";
echo &#39;字符串 “&#39;.$str.&#39;” 占：&#39;.strlen($str).&#39; 个字节<br>&#39;;
?>

#In the above example, it contains two Chinese characters, so it occupies 6 bytes.

<?php
header("Content-type:text/html;charset=utf-8");
$str = "hello，欢迎来到这里！";
echo &#39;字符串 “&#39;.$str.&#39;” 占：&#39;.strlen($str).&#39; 个字节<br>&#39;;
?>

In the above example, it contains 5 English characters, 6 Chinese characters, a Chinese exclamation mark and a Chinese comma; therefore it occupies 5 (8*3) = 29 characters Festival.

Note: When calculating the number of characters in a string, the strlen() function can only process English strings and is not friendly to Chinese or mixed Chinese and English strings. At this time, you need to use the

mb_strlen() function, which can calculate the string length based on characters .

Extended knowledge: mb_strlen() function

mb_strlen() function can also return the length of the string. The syntax format is as follows:

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

• $str is the string whose length needs to be calculated

• $encoding is an optional parameter, which is the character encoding. If omitted, the internal character encoding is used.

The return value of the mb_strlen() function is the number of characters contained in the string $str with $encoding encoding. If $encoding is invalid, false is returned.

Note: Unlike the strlen() function, in the mb_strlen() function, whether it is Chinese characters, English, numbers, decimal points, underscores and spaces, they only occupy one character in length.

[Example] Use the mb_strlen() function to get the string length.

<?php
header("Content-type:text/html;charset=utf-8");
$str = "hello 你好!";
echo &#39;字符串 “&#39;.$str.&#39;” 的长度为：&#39;.mb_strlen($str,"utf-8").&#39;<br>&#39;;

$str = "欢迎来到PHP中文网！";
echo &#39;<br>字符串 “&#39;.$str.&#39;” 的长度为：&#39;.mb_strlen($str,&#39;utf-8&#39;).&#39;<br>&#39;;
?>

It can be seen that we can well handle the length problem of Chinese strings by setting the corresponding $encoding parameters.

Recommended learning: "PHP Video Tutorial"

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