Comparison of strlen() and mb_strlen() in PHP

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First take a look at what the official documentation says;

strlen()-used to get the string length

##intstrlen(string$ string)

Returns the length of the given stringstring.

mb_strlen—Get the length of the string

##mixedmb_strlen(string$str[,string$encoding= mb_internal_encoding()] )

string.

str:Thestringto check the length of.

encoding: Theencodingparameter is the character encoding. If omitted, the internal character encoding is used.

Note: The strlen() function cannot correctly handle Chinese strings. It only gets the number of bytes occupied by the string.

In strlen(), the encoding is GB2312, and one Chinese character occupies 2 bytes. If encoded as utf-8, one Chinese character occupies 3 bytes.

However,

In mb_strlen(), if the encoding is utf-8, the length of a Chinese character output is 1. Code to help understand:

"; $_str_y = "hello"; $_str_c = "你好"; //strlen() echo "strlen()输出hello的长度".strlen($_str_y)."
"; echo "strlen()输出'你好'的长度".strlen($_str_c)."
"; /** * 输出： * strlen()输出hello的长度5 * strlen()输出'你好'的长度6 */ //mb_strlen() echo "mb_strlen( 不指定字符编码 )输出hello的长度".mb_strlen($_str_y)."
"; echo "mb_strlen( 不指定字符编码 )输出'你好'的长度".mb_strlen($_str_c)."
"; /** * mb_strlen( 不指定字符编码 )输出hello的长度5 * mb_strlen( 不指定字符编码 )输出'你好'的长度6 */ //mb_strlen() echo "mb_strlen( utf-8 )输出hello的长度".mb_strlen($_str_y,'utf-8')."
"; echo "mb_strlen( utf-8 )输出'你好'的长度".mb_strlen($_str_c,'utf-8')."
"; /** * 输出： * mb_strlen( utf-8 )输出hello的长度5 * mb_strlen( utf-8 )输出'你好'的长度2 */ ?>

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 it is not commented out, otherwise the problem of undefined function will occur.

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