Common functions used in php to calculate the string length include strlen and mb_strlen. The following is a comparison of the two functions (encoding method UTF8. comparison between strlen and mb_strlen when the characters are all English characters, the two are the same. Here we will mainly compare the two calculation results when mixing Chinese and English. (The encoding method is UTF8 during testing)
Common functions used in php to calculate the string length include strlen and mb_strlen. The following is a comparison of the two functions (encoding method UTF8. comparison between strlen and mb_strlen when the characters are all English characters, the two are the same. Here we will mainly compare the two calculation results when mixing Chinese and English. (The encoding method is UTF8 during testing)
Common functions used in php to calculate the string length include strlen and mb_strlen. The following is a comparison of the two functions (encoding method UTF8)
1. Compare strlen and mb_strlen
When all the characters are English characters, the two are the same. Here we will mainly compare the two calculation results when mixing Chinese and English. (The encoding method is UTF8 during testing)
'; Echo mb_strlen ($ str, 'utf8'); // output result // 14 // 6?>
Result Analysis: During strlen calculation, the Chinese character of UTF8 is 3 characters in length, so the length of "Chinese character a 1 character" is 3*4 + 2 = 14
When mb_strlen is calculated, if the selected inner code is UTF8, a Chinese character is regarded as 1 in length. Therefore, the length of "Chinese a character 1 character" is 6.
2. placeholder Calculation for Chinese and English mixed strings:
The two functions can be used to calculate the placeholder value of a string in both Chinese and English (the placeholder value of a Chinese character is 2 and that of an English character is 1). The calculation method is as follows: if a mixed string has a Chinese character and B English character, the placeholder is:
For example, the strlen ($ str) Value of "Chinese character a 1 character" is 14, and the mb_strlen ($ str) value is 6, the placeholder Value of "Chinese character a 1 character" is 10.
The built-in String Length function strlen in PHP cannot properly process Chinese strings. It only obtains the number of bytes occupied by strings. For GB2312 Chinese encoding, strlen obtains two times the number of Chinese characters, and for the UTF-8 encoding of Chinese, is three times the difference (in the UTF-8 encoding, A Chinese Character occupies 3 bytes ).
Using the mb_strlen function can better solve this problem. The usage of mb_strlen is similar to that of strlen, except that it has a second optional parameter for specifying character encoding. For example, you can use mb_strlen ($ str, 'utf-8') to get the $ str length of the UTF-8 '). If the second parameter is omitted, the internal code of PHP is used. The internal encoding can be obtained through the mb_internal_encoding () function. It should be noted that mb_strlen is not a PHP core function. before using it, make sure that. the "php_mbstring.dll" line is loaded in ini to ensure that the "extension = php_mbstring.dll" line exists and is not commented out. Otherwise, the problem of undefined functions may occur.
