DateTime dt = DateTime.Now; //本地时间
string str0 = dt.ToString();
Console.WriteLine(str0); //2025-01-17 16:05:34
//将本地时间输出为ISO 8601格式字符串,东八区后面会+08:00
string str1 = dt.ToString("yyyy-MM-ddTHH:mm:sszzzz");
Console.WriteLine(str1); //2025-01-17T16:05:34+08:00
//将本地时间转成协调时间时(UTC)后输出为ISO 8601格式字符串,UTC时间后面会有个Z
string str2 = dt.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ssZ");
Console.WriteLine(str2); //2025-01-17T08:05:34Z
var dt0 = Convert.ToDateTime(str0); //ToDateTime可以把各类型的日期字符串转成本地时间
var dt1 = Convert.ToDateTime(str1);
var dt2 = Convert.ToDateTime(str2);
Console.WriteLine("dt0=" + dt0); //2025-01-17 16:05:34
Console.WriteLine("dt1=" + dt1); //2025-01-17 16:05:34
Console.WriteLine("dt2=" + dt2); //2025-01-17 16:05:34