php strlen mb_strlen calculates the length of mixed Chinese and English strings

php strlen mb_strlen calculates the length of mixed Chinese and English strings_PHP tutorial

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Release： 2016-07-21 15:45:31

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Compare strlen and mb_strlen
When the characters are all English characters, the two are the same. Here we mainly compare the two calculation results when Chinese and English are mixed. (The encoding method during testing is UTF8)

Copy code The code is as follows:

$str= 'Chinese a character 1 character'; 
echo strlen($str); 
echo '
'; 
echo mb_strlen($str,'UTF8'); 
// Output result 
//14 
//6 
?> 

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, if the internal code is selected to be UTF8, a Chinese character will be calculated as a length of 1, so "Chinese a character 1 character" "The length is 6
About the placeholder calculation of Chinese and English mixed strings:
Using these two functions, you can jointly calculate the placeholder of a Chinese and English mixed string. (The placeholder for a Chinese character is 2, and the placeholder for an English character is 1). The calculation method is: if a mixed string has a Chinese character and b English character, the placeholder is:

Copy code The code is as follows:

$str='Chinese a character 1 character'; 
//The calculation is as follows
 echo (strlen($str) + mb_strlen($str,'UTF8')) / 2; 
echo 
//Output result
//10 
?> 

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.
Attached is an article from the website:
Still a question about Chinese. 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 is not commented out, otherwise it will be undefined. function problem.