Conversion between C# timestamp and time

The timestamp is actually the number of seconds or milliseconds from the current time to the time you want to calculate from 0:00:00:00 on January 1, 1970 (converted to Beijing time is 08:00:00:00 on January 1, 1970)

Generally speaking: the timestamp we use is 10 digits in seconds, and 13 digits in milliseconds

1. Conversion between time time and second timestamp

1. Convert the time time to a second timestamp

  DateTime time = DateTime.Now;
  System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1));//当地时区
  TimeSpan ts = time - startTime; 
  var timestamp = Convert.ToInt64(ts.TotalSeconds);
  Console.WriteLine(timestamp);

2. Convert the second timestamp to time

  long timestamp=1629160713;
  System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1));//当地时区
  var time = startTime.AddSeconds(timestamp);

2. Conversion between time time and millisecond timestamp

1. Convert time time to millisecond timestamp

  TimeSpan ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
  var timestamp= Convert.ToInt64(ts2.TotalMilliseconds);
  Console.WriteLine(timestamp);

2. Convert the millisecond timestamp to time

  System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1));//当地时区  
  var time = startTime.AddMilliseconds(cc);

Note:
UtcNow The standard time zone is obtained, while TimeZone.CurrentTimeZone.ToLocalTimethe local time zone is obtained, so there are two ways to obtain the time difference

  //当地时区
  System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1)); // 当地时区
  TimeSpan ts = DateTime.Now - startTime; 

  //标准时区
  TimeSpan ts2 = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);