递归多维数组变成一维数组

	/**
	 * 递归
	 * @param unknown $arr
	 * @return boolean|multitype:unknown
	 */
	public function ar($arr){
		static $tmp=array();
		if (!is_array ($arr)){
			return false;
		}
		foreach ($arr as $val ){
			if (is_array ($val)){
				$this->ar($val);
			}else{
				$tmp[]=$val;
			}
		}
		return $tmp;
	}