Convert 10 digit Julian date to DateTime

Question

I tried to convert 1368463365 which is an int field in sql server database with the following code

public static DateTime JulianToDateTime(int julianDate)
{
    int RealJulian = julianDate + 1900000;
    int year = Convert.ToInt32(RealJulian.ToString().Substring(0, 4));
    int DoY = Convert.ToInt32(RealJulian.ToString().Substring(4));
    DateTime d = new DateTime(year, 1, 1);
    return d.AddDays(DoY - 1);
}

Define "Julian Date" here. It looks like you are referring to the text representation of a mashed number since 1900 (which is not a [Julian Date](http://en.wikipedia.org/wiki/Julian_day)). — user2864740, Feb 18 '14 at 18:47
Show sample input and expected output, or describe more precisely your problem. — MarcinJuraszek, Feb 18 '14 at 18:48
possible duplicate of [How to convert UNIX timestamp to DateTime and vice versa?](http://stackoverflow.com/questions/249760/how-to-convert-unix-timestamp-to-datetime-and-vice-versa) — L.B, Feb 18 '14 at 18:59

score 3 · Answer 1 · answered Feb 18 '14 at 18:55

Your input is not a julian date. It's a timestamp. 1368463365 refers to Mon, 13 May 2013 16:42:45 GMT.

You can use following method to get DateTime from timestamp:

public static DateTime UnixTimeStampToDateTime( int unixTimeStamp )
{
    // Unix timestamp is seconds past epoch
    System.DateTime dtDateTime = new DateTime(1970,1,1,0,0,0,0);
    dtDateTime = dtDateTime.AddSeconds( unixTimeStamp ).ToLocalTime();
    return dtDateTime;
}

score 3 · Accepted Answer · edited May 23 '17 at 12:02

It looks like you have a Unix timestamp there. The value 1368463365 would be equivalent with 13 May 2013 16:42:45 GMT.

A Unix timestamp is simply the number of seconds since midnight January 1st, 1970 UTC/GMT. So you can convert it to a regular DateTime like this:

public static DateTime UnixTimeToDateTime(long timestamp)
{
    var dateTime = new DateTime(1970, 1, 1, 0, 0, 0, 0);
    dateTime = dateTime.AddSeconds((double)timestamp);
    dateTime = dateTime.ToLocalTime();  // Change GMT time to your timezone
    return dateTime;
}

Adapted from this answer. Usage:

long timestamp = 1368463365;
Console.WriteLine(UnixTimeToDateTime(timestamp));

Result (on my Dutch computer, in UTC+2):

13-5-2013 18:42:45

score 2 · Answer 3 · edited May 23 '17 at 10:10

The number 1368463365 is Unix timestamp and it's number of seconds since 1/1/1970. In that case what you have to do is to just add this timestamp to DateTime representing the the date 1/1/1970 00:00:00.

Example code from another SO question:

public static DateTime UnixTimeStampToDateTime( double unixTimeStamp )
{
    // Unix timestamp is seconds past epoch
    System.DateTime dtDateTime = new DateTime(1970,1,1,0,0,0,0);
    dtDateTime = dtDateTime.AddSeconds( unixTimeStamp ).ToLocalTime();
    return dtDateTime;
}

Check this SO question for reference.

And BTW, there's a little place for mistake here, but if you want to check what date such timestamp represents, you can check it online with this converter.

score 1 · Answer 4 · answered Feb 18 '14 at 19:02

Insofar as I know, Julian Date can mean

The count of days since 1 January 4713 BCE at 12:00:00 pm (Noon) UTC in the Julian Calendar, which is 24 November 4714 BCE in the Gregorian calendar. Today 18 February 2014 is JD 2456706 (for at least part of the day.)
The ordinal day of the year (e.g. 31 December 2013 is 2013365; 31 December 2012 is 2012366.

None of these are 10 digits. For conversion to/from the former, see http://aa.usno.navy.mil/faq/docs/JD_Formula.php (your tax dollars at work...or at least my tax dollars at work).

Conversion to/from the ordinal date form should be pretty obvious:

string   julianDate       = "2014323" ; // the 323rd day of  2014
int      year             = int.Parse( julianDate.substring(0,4) ) ;
int      ordinalDayNumber = int.Parse( julianDate.substring(4,3) ) ;
DateTime dt               = new DateTime(year,1,1).AddDays( ordinalDayNumber - 1 ) ;

score 1 · Answer 5 · answered Feb 18 '14 at 19:21

1

The unix time is a the number of seconds since midnight January 1, 1970 UTC.

DateTime UnixTimeToDateTime(int timestamp)
{
    return new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddSeconds(timestamp);
}

answered Feb 18 '14 at 19:21

NickC

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Convert 10 digit Julian date to DateTime

5 Answers5