python 获取当前时间，获取几天前的时间

def getdate(beforeday):
    today = datetime.datetime.now()
    todaystr = str(today).split(".")[0]								 # 这是当前时间
    print(todaystr)
    offset = datetime.timedelta(days=-beforeday)	 # 计算偏移量
    re_date = (today + offset).strftime('%Y-%m-%d')	 # 获取想要的日期的时间
    print(re_date+" 00:00:00")
    return re_date

if __name__ == '__main__':
    beforeday = 30
    getdate(beforeday)