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Homephp教程php手册最准确的php截取字符串长度函数,截取字符串

最准确的php截取字符串长度函数,截取字符串

说是最精确截取长度,其实我也不敢确定是否是最精确的,具体有多精确看下面的效果就知道了:
先上测试用的字符串:

<&#63;php 
header("Content-Type:text/html;charset=utf-8"); 
echo cn_substr_utf8('我是一个,和哈,哦也,,国家!',12); 
echo '<br />',cn_substr_utf8('ai\'2145m a ch3我[是一,个,和哈,哦也,,国家!',12); 
echo '<br />',cn_substr_utf8('【我,是一,个,和哈,哦也,,国家!',12); 
echo '<br />',cn_substr_utf8('我是一,个,和哈,哦也,,国家!',12); 
echo '<br />',cn_substr_utf8('我是,一,个,和哈,哦也,,国家!',12); 
echo '<br />',cn_substr_utf8('我,是,一,个,和哈,哦也,,国家!',12); 
echo '<br />',cn_substr_utf8('我是asd一,个,和哈,哦也,,国家!',12); 
echo '<br />',cn_substr_utf8('【我i\'m[是一,个,和哈,哦也,,国家!',12); 
echo '<br />',cn_substr_utf8('【i\'m a ch我[是一,个,和哈,哦也,,国家!',12); 
echo '<br />',cn_substr_utf8('【i\'2145m a ch3我[是一,个,和哈,哦也,,国家!',12); 

下面是精确截取字符串的效果图:


具体函数代码如下:

//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 ''; 
  } 
  preg_match_all("/./su",$str,$ar); 
  $str2=''; 
  $tstr=''; 
  //www.phpernote.com 
  for($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&#63;$str2:$str2.$append; 
} 

如果大家认为还不够准确大家可以在此基础上进行改进,或者是创新,希望这篇关于php截取字符串长度函数的文章对大家的学习有所帮助。

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