A brief analysis of the difference between strlen() and mb_strlen() in PHP_PHP Tutorial

Common functions for calculating string length in PHP are: 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.

Let’s look at an example first:

Copy code The code is as follows:

//The encoding method of the file during testing must be UTF8
$str='Chinese character a';
echo strlen($str).'
';//14
echo mb_strlen($str,'utf8').'
';//6
echo mb_strlen($str,'gbk').'
';//8
echo mb_strlen($str,'gb2312').'
';//10
?>

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)

Copy code The code is as follows:

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:

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 3 times (under UTF-8 encoding, one Chinese character occupies 3 characters Festival).

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.

Note: 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 undefined function problems will occur.

http://www.bkjia.com/PHPjc/825400.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/825400.htmlTechArticleCommon functions for calculating the length of strings in PHP are: strlen and mb_strlen. When the characters are all English characters At the same time, the two are the same. The main comparison here is that when Chinese and English are mixed,...