A brief analysis of the difference between strlen and mb_strlen in PHP, strlenmb_strlen_PHP tutorial

A brief analysis of the difference between strlen and mb_strlen in PHP, strlenmb_strlen

In PHP, strlen and mb_strlen are functions to find the length of a string, but for some beginners, they may not be clear about the difference without reading the manual.
The difference between the two is explained below through examples.

Look at the example first:

<&#63;php 
//测试时文件的编码方式要是UTF8 
$str='中文a字1符'; 
echo strlen($str).'<br>';//14 
echo mb_strlen($str,'utf8').'<br>';//6 
echo mb_strlen($str,'gbk').'<br>';//8 
echo mb_strlen($str,'gb2312').'<br>';//10 
&#63;> 

Result analysis: When calculating strlen, a UTF8 Chinese character is treated as 3 lengths, so the length of "Chinese a character 1 character" is 3*4+2=14. When calculating mb_strlen, the selected internal code is UTF8, a Chinese character will be calculated as a length of 1, so the length of "Chinese a character 1 character" is 6.

Using these two functions, you can jointly calculate the occupancy of a mixed Chinese and English string (the occupancy of a Chinese character is 2, and the occupancy of an English character is 1)

echo (strlen($str) + mb_strlen($str,'UTF8')) / 2; 

For example, the strlen($str) value of "Chinese a character 1 character" is 14, and the mb_strlen($str) value is 6, then it can be calculated that the placeholder of "Chinese a character 1 character" is 10.

echo mb_internal_encoding(); 

PHP’s built-in string length function strlen cannot correctly handle Chinese strings. It only gets the number of bytes occupied by the string. For GB2312 Chinese encoding, the value obtained by strlen is twice the number of Chinese characters, while for UTF-8 encoded Chinese, the difference is three times (under UTF-8 encoding, one Chinese character occupies 3 bytes).

Using the mb_strlen function can better solve this problem. The usage of mb_strlen is similar to strlen, except that it has a second optional parameter to specify the character encoding. For example, to get the UTF-8 string $str length, you can use mb_strlen($str,'UTF-8'). If the second parameter is omitted, PHP's internal encoding will be used. The internal encoding can be obtained through the mb_internal_encoding() function.

It should be noted that mb_strlen is not a core function of PHP. Before using it, you need to make sure that php_mbstring.dll is loaded in php.ini, that is, make sure that the line "extension=php_mbstring.dll" exists and has not been commented out, otherwise it will An undefined function problem occurred.

strlen calculates the string length, one Chinese character is 2 characters
mb_strlen counts the characters quot
count according to its character encoding mode to calculate the number of elements in the array or the number of attributes in the object

strlen and mb_strlen are functions to find the length of a string
The following is an example to explain the difference between the two.
';//14echo mb_strlen($str,' utf8').'
';//6echo mb_strlen($str,'gbk').'
';//8echo mb_strlen($str,'gb2312').'
' ;//10?> It should be noted that mb_strlen is not a core function of PHP. Before using it, you need to make sure that php_mbstring.dll is loaded in php.ini, that is, make sure that the line "extension=php_mbstring.dll" exists and is not commented. Otherwise, undefined function problems will occur.