日期时间转换c#

DateTime date = DateTime.Now;
string dateString = date.ToString("yyyy-MM-dd");

string dateString = "2022-01-01";
DateTime date = DateTime.ParseExact(dateString, "yyyy-MM-dd", CultureInfo.InvariantCulture);

DateTime time = DateTime.Now;
string timeString = time.ToString("HH:mm:ss");

string timeString = "12:34:56";
DateTime time = DateTime.ParseExact(timeString, "HH:mm:ss", CultureInfo.InvariantCulture);

DateTime dateTime = DateTime.Now;
string dateTimeString = dateTime.ToString("yyyy-MM-dd HH:mm:ss");

string dateTimeString = "2022-01-01 12:34:56";
DateTime dateTime = DateTime.ParseExact(dateTimeString, "yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture);