<p> 以下代码试用于GB2312编码，截取中文字符串是PHP中一个头疼的问题，解决方法是根据值是否大于等于128来判断是否是双字节字符，以避免出现乱码的情况。但中英文混合、特殊符号等问题总是存在，现在写一个比较全面的，仅供参考：</p><p> 程序说明：</p><p> 1. len 参数以中文字符为标准，1len等于2个英文字符，为了形式上好看些</p><p> 2. 如果将magic参数设为false，则中文和英文同等看待，取绝对的字符数</p><p> 3. 特别适用于用htmlspecialchars()进行过编码的字符串</p><p> 4. 能正确处理GB2312中实体字符模式（𖰰）</p><p> 程序代码：</p><code>function FSubstr($title,$start,$len="",$magic=true)<br />{<br />/**<br /> * powered by Smartpig<br /> * mailto:d.einstein@263.net<br /> */<br /> <br />$length = 0;<br />if($len == "") $len = strlen($title);<br />//判断起始为不正确位置<br />if($start > 0)<br />{<br /> $cnum = 0;<br /> for($i=0;$i<$start;$i++)<br /> {<br /> if(ord(substr($title,$i,1)) >= 128) $cnum ++;<br /> }<br /> if($cnum%2 != 0) $start--;<br /> <br /> unset($cnum);<br />}<br />if(strlen($title)<=$len) return substr($title,$start,$len);<br />$alen = 0;<br />$blen = 0;<br />$realnum = 0;<br />for($i=$start;$i<strlen($title);$i++)<br />{<br /> $ctype = 0;<br /> $cstep = 0;<br /> $cur = substr($title,$i,1);<br /> if($cur == "&")<br /> {<br /> if(substr($title,$i,4) == "<")<br /> {<br /> $cstep = 4;<br /> $length += 4;<br /> $i += 3;<br /> $realnum ++;<br /> if($magic)<br /> {<br /> $alen ++;<br /> }<br /> }<br /> else if(substr($title,$i,4) == ">")<br /> {<br /> $cstep = 4;<br /> $length += 4;<br /> $i += 3;<br /> $realnum ++;<br /> if($magic)<br /> {<br /> $alen ++;<br /> }<br /> }<br /> else if(substr($title,$i,5) == "&")<br /> {<br /> $cstep = 5;<br /> $length += 5;<br /> $i += 4;<br /> $realnum ++;<br /> if($magic)<br /> {<br /> $alen ++;<br /> }<br /> }<br /> else if(substr($title,$i,6) == """)<br /> {<br /> $cstep = 6;<br /> $length += 6;<br /> $i += 5;<br /> $realnum ++;<br /> if($magic)<br /> {<br /> $alen ++;<br /> }<br /> }<br /> else if(substr($title,$i,6) == "'")<br /> {<br /> $cstep = 6;<br /> $length += 6;<br /> $i += 5;<br /> $realnum ++;<br /> if($magic)<br /> {<br /> $alen ++;<br /> }<br /> }<br /> else if(preg_match("/&#(d+);/i",substr($title,$i,8),$match))<br /> {<br /> $cstep = strlen($match[0]);<br /> $length += strlen($match[0]);<br /> $i += strlen($match[0])-1;<br /> $realnum ++;<br /> if($magic)<br /> {<br /> $blen ++;<br /> $ctype = 1;<br /> }<br /> }<br /> }else{<br /> if(ord($cur)>=128)<br /> {<br /> $cstep = 2;<br /> $length += 2;<br /> $i += 1;<br /> $realnum ++;<br /> if($magic)<br /> {<br /> $blen ++;<br /> $ctype = 1;<br /> }<br /> }else{<br /> $cstep = 1;<br /> $length +=1;<br /> $realnum ++;<br /> if($magic)<br /> {<br /> $alen++;<br /> }<br /> }<br /> }<br /> <br /> if($magic)<br /> {<br /> if(($blen*2+$alen) == ($len*2)) break;<br /> if(($blen*2+$alen) == ($len*2+1))<br /> {<br /> if($ctype == 1)<br /> {<br /> $length -= $cstep;<br /> break;<br /> }else{<br /> break;<br /> }<br /> }<br /> }else{<br /> if($realnum == $len) break;<br /> }<br />}<br />unset($cur);<br />unset($alen);<br />unset($blen);<br />unset($realnum);<br />unset($ctype);<br />unset($cstep);<br />return substr($title,$start,$length);<br />}</code></p>