How to use regular expressions in php to match only Chinese characters

In PHP, you can use the regular expression "/[\x{4e00}-\x{9fff}] /u" and the preg_match_all() function to match only Chinese characters, the syntax "preg_match_all("/[ \x{4e00}-\x{9fff}". The preg_match_all() function will search for all results in the string that can match the regular expression, matching "/[\x{4e00}-\x{9fff}] /u "You can filter the string and only get Chinese characters.

The operating environment of this tutorial: Windows 7 system, PHP 8 version, DELL G3 computer

In php, you can use the regular expression "/[\x{4e00}-\x{9fff}] /u" and the preg_match_all() function to match only Chinese characters.

preg_match_all() function will search for all results in the string that can match the regular expression

preg_match_all(pattern,subject,matches,flags,offset)

The parameter description is as follows:

• pattern: the pattern to be searched, also It is a defined regular expression;
• subject: the string to be searched;
• matches: optional parameters (multi-dimensional array), used to store all matching results, the array is sorted by $ flags specified;
• flags: optional parameters, which can be used in combination with the following flags (note that PREG_PATTERN_ORDER and PREG_SET_ORDER cannot be used at the same time):
  • PREG_PATTERN_ORDER: The results are sorted by $matches[0] Save complete All matches of the pattern, $matches[1] saves all matches of the first subgroup, and so on.
  • PREG_SET_ORDER: The results are sorted as $matches[0] contains all matches obtained from the first match ( including subgroups), $matches[1] is an array containing all matches (including subgroups) found in the second match, and so on.
  • PREG_OFFSET_CAPTURE: If this flag is passed, each found When a match is returned, it will increase its offset relative to the target string. Note that this will change each match result string element in $matches, making it a match result string with the 0th element and a match result string with the 1st element. The offset of the matching result string in the subject.
• offset: Optional parameter, $offset is used to start searching from the specified position in the target string (unit is bytes).

The preg_match_all() function can return the number of matches of pattern (possibly 0), or FALSE if an error occurs.

preg_match_all() function can filter strings with the regular expression "/[\x{4e00}-\x{9fff}] /u", only Get Chinese characters.

Note: preg_match_all() function will store the matching function characters one by one in an array (the array is specified by the third parameter).

<?php
header("Content-type:text/html;charset=utf-8");
$str = "欢迎4546来到php这里。zblog,我的?#$%^天呀&())*(&^";
echo $str;
preg_match_all("/[\x{4e00}-\x{9fff}]+/u","$str",$arr);
var_dump($arr);
?>

At this time, you can use the implode() function to splice the result value into a string.

implode('',$arr[0])

Extended knowledge: implode() function

implode() function returns a string composed of array elements.

implode(separator,array)

• separator: Optional. Specifies what is placed between array elements. Default is "" (empty string).

• array: required. Arrays to be combined into strings.

Return value: Returns a string composed of array elements.

There is also a function that has the same function as the implode() function: join(). The join() function is an alias of the implode() function.

Recommended learning: "PHP Video Tutorial"

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