在thinkphpu公共函数库下定义这个函数；函数如下:

//$str=strip_tags($str);可以在第二行加这句，表示先剔除html标签

• function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=false){

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• if(function_exists("mb_substr")){

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• if($suffix)

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• return mb_substr($str, $start, $length, $charset).".";

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• else

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• return mb_substr($str, $start, $length, $charset);

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• }elseif(function_exists('iconv_substr')) {

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• if($suffix)

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• return iconv_substr($str,$start,$length,$charset).".";

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• else

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• return iconv_substr($str,$start,$length,$charset);

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• }

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• $re['utf-8'] = "/[x01-x7f]|[xc2-xdf][x80-xbf]|[xe0-xef][x80-xbf]{2}|[xf0-xff][x80-xbf]{3}/";

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• $re['gb2312'] = "/[x01-x7f]|[xb0-xf7][xa0-xfe]/";

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• $re['gbk'] = "/[x01-x7f]|[x81-xfe][x40-xfe]/";

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• $re['big5'] = "/[x01-x7f]|[x81-xfe]([x40-x7e]|xa1-xfe])/";

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• preg_match_all($re[$charset], $str, $match);

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• $slice = join("",array_slice($match[0], $start, $length));

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• if($suffix) return $slice."…";

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• return $slice;

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• }