The difference between strlen and Mb_strlen in PHP _php tutorial

In PHPIn strlenAnd Mb_strlenis a function of the length of the string, but for some beginners, if you do not read the manual, it may not be clear that the difference.
The difference between the two is explained in the following example.

First look at the example:

 
 

  
  

  
 
  
  

  
//Test file encoding method if UTF8  
  
  

  
$str = ' Chinese a character 1 characters ' ; 
  
  

  
Echo   strlen($str). '
'; //14  
  
  

  
Echo Mb_strlen ($str,' UTF8 '). '
'; //6  
  
  

  
Echo Mb_strlen ($str,' GBK '). '
'; //8  
  
  

  
Echo Mb_strlen ($str,' gb2312 '). '
'; //10  
  
  

  
?>
 
 

Results analysis: In the strlen calculation, the treatment of a UTF8 character is 3 length, so "Chinese a character 1 characters" length is 3*4+2=14, in the Mb_strlen calculation, the selected inner code is UTF8, will be a Chinese character as the length of the calculation, so "a character 1 characters" The length is 6.

The two functions can be combined to calculate the number of placeholders for a mixed Chinese-English string (a placeholder for a Chinese character is 2, the English character is 1)

 
  
  

  
   
   
Echo (strlen($str) + mb_strlen ($str,' UTF8 ') 
 
  
  

For example, the strlen ($STR) value of the Chinese a character 1 character is 14,mb_strlen ($STR) value is 6, then you can calculate the placeholder for the "Chinese-a-word 1-character" is 10.

 
  
  

  
   
   
Echo
 
  
  

PHP built-in string length function strlen cannot handle Chinese strings correctly, it only gets the number of bytes that the string occupies. For the Chinese encoding of GB2312, strlen get the value is twice times the number of Chinese characters, and for UTF-8 encoded in Chinese, is 3 times times the difference (in UTF-8 encoding, a Chinese character accounted for 3 bytes).

Using Mb_strlen function can solve this problem well. The usage of Mb_strlen is similar to strlen, except that it has a second optional parameter for specifying character encoding. For example get UTF-8 string $str length, can be used Mb_strlen ($str, ' UTF-8 '). If you omit the second argument, the internal encoding of PHP is used. The internal code can be obtained through the mb_internal_encoding () function.

It is important to note that Mb_strlen is not a PHP core function and needs to be sure that the Php_mbstring.dll is loaded in the php.ini before use, that is, to ensure that the "Extension=php_mbstring.dll" line is present and not commented out. Otherwise, there is an issue with undefined functions.

http://www.bkjia.com/PHPjc/445811.html www.bkjia.com true http://www.bkjia.com/PHPjc/445811.html techarticle in PHP, strlen and Mb_strlen are functions that seek the length of a string, but for some beginners it may not be clear what the difference is if you don't read the manual. Here's an example of ...

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