PHP Chinese string interception function supports multiple encodings

/*
* @todo Chinese interception, support gb2312, gbk, utf-8, big5
* @http://bbs.it-home.org
* @param string $str The string to be intercepted
* @param int $start The interception starting position
* @param int $length The interception length
* @param string $charset utf-8|gb2312|gbk|big5 encoding
* @ param $suffix whether to add a suffix
*/
function csubstr($str, $start=0, $length, $charset="utf-8", $suffix=true)
{
if(function_exists("mb_substr"))
return mb_substr($str, $start, $length, $charset);
$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]/";
$re ['big5'] = "/[x01-x7f]|[x81-xfe]([x40-x7e]|xa1-xfe])/";
preg_match_all($re[$charset], $str, $match) ;
$slice = join("",array_slice($match[0], $start, $length));
if($suffix) return $slice."…";
return $slice;
}
?> ;

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