PHP 截取中文字符函数

可通过以下函数针对 thinkphp 模板截取内容简介如： {$content|msubstr=0,20}

function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true){
$re["utf-8"] = "/[x01-x7f]|[xc2-xdf][x80-xbf]|[xe0-xef][x80-xbf]{2}|[xf0-xff][x80-xbf]{3}/";
$re["gb2312"] = "/[x01-x7f]|[xb0-xf7][xa0-xfe]/";
$re["gbk"] = "/[x01-x7f]|[x81-xfe][x40-xfe]/";
$re["big5"] = "/[x01-x7f]|[x81-xfe]([x40-x7e]|xa1-xfe])/";
$str = strip_tags($str);
preg_match_all($re[$charset], $str, $match);
$str_lenth = count($match[0]);
if(function_exists("mb_substr")){
if($suffix && $str_lenth>$length)
return mb_substr($str, $start, $length, $charset)."...";
else
return mb_substr($str, $start, $length, $charset);
}elseif(function_exists("iconv_substr")) {
if($suffix && $str_lenth>$length)
return iconv_substr($str,$start,$length,$charset)."...";
else
return iconv_substr($str,$start,$length,$charset);
}
}