About php interception string length function

This article mainly introduces the PHP interception string length function. Interested friends can refer to it. I hope it will be helpful to everyone.

First enter the string for testing:

<?php 
header("Content-Type:text/html;charset=utf-8"); 
echo cn_substr_utf8(&#39;我是一个，和哈，哦也，，国家！&#39;,12); 
echo &#39;<br />&#39;,cn_substr_utf8(&#39;ai\&#39;2145m a ch3我[是一，个，和哈，哦也，，国家！&#39;,12); 
echo &#39;<br />&#39;,cn_substr_utf8(&#39;【我，是一，个，和哈，哦也，，国家！&#39;,12); 
echo &#39;<br />&#39;,cn_substr_utf8(&#39;我是一，个，和哈，哦也，，国家！&#39;,12); 
echo &#39;<br />&#39;,cn_substr_utf8(&#39;我是,一，个，和哈，哦也，，国家！&#39;,12); 
echo &#39;<br />&#39;,cn_substr_utf8(&#39;我,是,一，个，和哈，哦也，，国家！&#39;,12); 
echo &#39;<br />&#39;,cn_substr_utf8(&#39;我是asd一，个，和哈，哦也，，国家！&#39;,12); 
echo &#39;<br />&#39;,cn_substr_utf8(&#39;【我i\&#39;m[是一，个，和哈，哦也，，国家！&#39;,12); 
echo &#39;<br />&#39;,cn_substr_utf8(&#39;【i\&#39;m a ch我[是一，个，和哈，哦也，，国家！&#39;,12); 
echo &#39;<br />&#39;,cn_substr_utf8(&#39;【i\&#39;2145m a ch3我[是一，个，和哈，哦也，，国家！&#39;,12);

The following is the rendering of accurately intercepting the string:

The specific function code is as follows :

//utf-8中文截取，单字节截取模式 
function cn_substr_utf8($str,$length,$append='...',$start=0){ 
  if(strlen($str)<$start+1){ 
    return &#39;&#39;; 
  } 
  preg_match_all("/./su",$str,$ar); 
  $str2=&#39;&#39;; 
  $tstr=&#39;&#39;; 
  //www.phpernote.com 
  for($i=0;isset($ar[0][$i]);$i++){ 
    if(strlen($tstr)<$start){ 
      $tstr.=$ar[0][$i]; 
    }else{ 
      if(strlen($str2)<$length + strlen($ar[0][$i])){ 
        $str2.=$ar[0][$i]; 
      }else{ 
        break; 
      } 
    } 
  } 
  return $str==$str2?$str2:$str2.$append; 
}

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

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