Chinese character interception function supported by Utf-8 and gb2312

/**
 * Utf-8、gb2312都支持的汉字截取函数
 * @param string $string 需要截取的文字
 * @param number $sublen 截取长度
 * @param number $start 开始位数
 * @param string $omitted 省略符
 * @param string $code 编码格式 默认UTF-8
 * @return string
 */
function cut_str($string, $sublen, $start = 0, $omitted = '...', $code = 'UTF-8')
{
	if($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, $sublen)).$omitted;
		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.= $omitted;
		return $tmpstr;
	}
}

The above introduces the Chinese character interception functions supported by Utf-8 and gb2312, including relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.