PHP custom Chinese string interception function substr_for_gb2312 and substr_for_utf8 examples, _PHP tutorial

Examples of php custom Chinese string interception functions substr_for_gb2312 and substr_for_utf8,

This article describes the usage of php custom Chinese string interception functions substr_for_gb2312 and substr_for_utf8. Share it with everyone for your reference, the details are as follows:

/*
*gb2312中文字符串截取
 */
function substr_for_gb2312($str,$start,$len=null)
 {
  $totlelength = strlen($str);
  //特例情况
  if ($len == null) $len = $totlelength;
  if ($len ==0) return "";
  if ($len >= $totlelength && $start == 0 ) return $str;
  if ($start > $totlelength) return "";
  //分析$start
  if ($start < 0 ) //$start<0时,转化为$start>0时的定位.
  {
  if ( abs($start) >= $totlelength ) $start = 0;
  else $start = $totlelength - abs($start);
  }
  //确定起始位置,当起始位拆分某汉字时,返回值包含此汉字.
  if ($start > 0)
  {
  $i = $start-1;
  $flag = -1;
  while ($i >= 0)
  {
  if ( ord(substr($str,$i,1)) > 160)
  {
  $flag = -1*$flag;
  }
  else break;
  $i--;
  }
  if($flag==1)
  {
  $start = $start - 1;
  $len++;    //保证不位移.
  }
 }
 $str = substr($str,$start);//截除字符串$str的$start位前的字符
 $totlelength = strlen($str);
 //确定结束位置,当结束位拆分某汉字时,返回值不包含此汉字.
 if ($len<0) $len = $totlelength - abs($len);
 if ($len <= 0) return "";
 $i=min($len,$totlelength);
 $i--;
 $flag = -1;
 while ($i >= 0)
 {
  if (ord(substr($str,$i,1))>160)
  {
   $flag=-1*$flag;
  }
  else break;
  $i--;
 }
 if($flag == 1)
  $len=$len-1;
 $subit=substr($str,0,$len);
 return $subit;
 }
/******************************************************************
* PHP截取UTF-8字符串，解决半字符问题。
* 英文、数字（半角）为1字节（8位），中文（全角）为3字节
* @return 取出的字符串, 当$len小于等于0时, 会返回整个字符串
* @param $str 源字符串
* $len 左边的子串的长度
****************************************************************/
function substr_for_utf($str,$len)
{
for($i=0;$i<$len;$i++)
{
$temp_str=substr($str,0,1);
if(ord($temp_str) > 127)
{
$i++;
if($i<$len)
{
$new_str[]=substr($str,0,3);
$str=substr($str,3);
}
}
else
{
$new_str[]=substr($str,0,1);
$str=substr($str,1);
}
}
return join($new_str);
}
&#63;>
/*带start位置的utf8截取函数*/
function utf8_substr($string, $start, $length) {
  preg_match_all ('/[/x00-/x7F]|[/xC2-/xDF][/x80-/xBF]|[/xE0-/xEF][/x80-/xBF][/x80-/xBF]|[/xF0-/xF4][/x80-/xBF][/x80-/xBF][/x80-/x
BF]/', $string, $rs);
  $out = '';
  $size = count ($rs[0]);
  $end = $start + $length;
  if ($end > $size ) {
    $end = $size;
  }
  for ($i = $start; $i < $end; $i++) {
    $out .= $rs[0][$i];
  }
  return $out;
}

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