Briefly describe the method of intercepting Chinese characters in PHP to prevent garbled characters

Directly using the PHP function substr to intercept Chinese characters may cause garbled characters. The main reason is that substr may "saw" a Chinese character in half. So let's see how to solve this problem.

I believe that everyone often uses interception of strings in their own programs, but often encounters the problem of garbled characters when intercepting Chinese strings. It is very troublesome. Next, we will introduce two methods to prevent garbled characters when intercepting Chinese strings.
First of all, a function written by yourself is convenient to use.
Use this function to intercept and there will be no garbled characters.

/** 
 * 支持中文字符串截取 
 */ 
function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true){ 
  switch($charset){ 
    case 'utf-8':$char_len=3;break; 
    case 'UTF8':$char_len=3;break; 
    default:$char_len=2; 
  } 
  //小于指定长度，直接返回 
  if(strlen($str)<=($length*$char_len)){   
    return $str; 
  } 
  if(function_exists("mb_substr")){  
    $slice= mb_substr($str, $start, $length, $charset); 
  }else if(function_exists(&#39;iconv_substr&#39;)){ 
    $slice=iconv_substr($str,$start,$length,$charset); 
  }else{ 
    $re[&#39;utf-8&#39;]  = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/"; 
    $re[&#39;gb2312&#39;] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/"; 
    $re[&#39;gbk&#39;]  = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/"; 
    $re[&#39;big5&#39;]  = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/"; 
    preg_match_all($re[$charset], $str, $match); 
    $slice = join("",array_slice($match[0], $start, $length)); 
  } 
  if($suffix) 
    return $slice; 
  return $slice; 
}

The second is a built-in function in PHP mb_substr function

Specify the encoding format of the string to be intercepted, just It can effectively prevent garbled characters.

Description

string mb_substr ( string $str , int $start [, int $length [, string $encoding ]] ) 
<?php 
 function substr_unicode($str, $s, $l = null) { 
   return join("", array_slice( 
     preg_split("//u", $str, -1, PREG_SPLIT_NO_EMPTY), $s, $l)); 
 } 
 
$str = "Büyük"; 
 $s = 0; // start from "0" (nth) char 
 $l = 3; // get "3" chars 
 echo substr($str, $s, $l) ."\n";  
 echo mb_substr($str, $s, $l) ."\n"; 
 echo substr_unicode($str, $s, $l); 
 ?>

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