PHP 截取字符串专题

1. 截取GB2312中文字符串

<?php
< ?php 
//截取中文字符串
function mysubstr($str, $start, $len) {
   $tmpstr = "";
   $strlen = $start + $len;
   for($i = 0; $i < $strlen; $i++) {
   if(ord(substr($str, $i, 1)) > 0xa0) {
   $tmpstr .= substr($str, $i, 2);
   $i++;
   } else
   $tmpstr .= substr($str, $i, 1);
   }
   return $tmpstr;
}
?>

2. 截取utf8编码的多字节字符串

<?php
< ?php
//截取utf8字符串
function utf8Substr($str, $from, $len)
{
   return preg_replace('#^(?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'.$from.'}'.
   '((?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'.$len.'}).*#s',
   '$1',$str);
}
?>
3. UTF-8、GB2312都支持的汉字截取函数

<?php
< ?php
/* 
Utf-8、gb2312都支持的汉字截取函数 
cut_str(字符串, 截取长度, 开始长度, 编码); 
编码默认为 utf-8 
开始长度默认为 0 
*/ 

function cut_str($string, $sublen, $start = 0, $code = 'UTF-8') 
{ 
   if($code == 'UTF-8') 
   { 
   $pa = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/"; 
   preg_match_all($pa, $string, $t_string); 

   if(count($t_string[0]) - $start > $sublen) return join('', array_slice($t_string[0], $start, $sublen))."..."; 
   return join('', array_slice($t_string[0], $start, $sublen)); 
   } 
   else 
   { 
   $start = $start*2; 
   $sublen = $sublen*2; 
   $strlen = strlen($string); 
   $tmpstr = ''; 

   for($i=0; $i< $strlen; $i++) 
   { 
   if($i>=$start && $i< ($start+$sublen)) 
   { 
   if(ord(substr($string, $i, 1))>129) 
   { 
   $tmpstr.= substr($string, $i, 2); 
   } 
   else 
   { 
   $tmpstr.= substr($string, $i, 1); 
   } 
   } 
   if(ord(substr($string, $i, 1))>129) $i++; 
   } 
   if(strlen($tmpstr)< $strlen ) $tmpstr.= "..."; 
   return $tmpstr; 
   } 
} 

$str = "abcd需要截取的字符串"; 
echo cut_str($str, 8, 0, 'gb2312'); 
?>
4. BugFree 的字符截取函数

<?php
< ?php 
/** 
* @package BugFree 
* @version $Id: FunctionsMain.inc.php,v 1.32 2005/09/24 11:38:37 wwccss Exp $ 
* 
* 
* Return part of a string(Enhance the function substr()) 
* 
* @author Chunsheng Wang <wwccss@263.net> 
* @param string $String the string to cut. 
* @param int $Length the length of returned string. 
* @param booble $Append whether append "...": false|true 
* @return string the cutted string. 
*/ 
function sysSubStr($String,$Length,$Append = false) 
{ 
   if (strlen($String) < = $Length ) 
   { 
   return $String; 
   } 
   else 
   { 
   $I = 0; 
   while ($I < $Length) 
   { 
   $StringTMP = substr($String,$I,1); 
   if ( ord($StringTMP) >=224 ) 
   { 
   $StringTMP = substr($String,$I,3); 
   $I = $I + 3; 
   } 
   elseif( ord($StringTMP) >=192 ) 
   { 
   $StringTMP = substr($String,$I,2); 
   $I = $I + 2; 
   } 
   else 
   { 
   $I = $I + 1; 
   } 
   $StringLast[] = $StringTMP; 
   } 
   $StringLast = implode("",$StringLast); 
   if($Append) 
   { 
   $StringLast .= "..."; 
   } 
   return $StringLast; 
   } 
} 

$String = "CodeBit.cn -- 简单、精彩、通用"; 
$Length = "18"; 
$Append = false; 
echo sysSubStr($String,$Length,$Append); 
?>