Convert Epoch Seconds to DMYHMS

From Erlang Community

[edit] Problem

You have a date and time in Erlang Epoch seconds (i.e., Gregorian calendar year 0 seconds), and you want to calculate the individual DMYHMS values from it.

[edit] Solution

In recipe TimeToday we did exactly this but only for the current date. How about if we wanted to get the date, and time (DMYHMS) associated to a particular number of seconds? Once more we would use gre.

1> Seconds = 1083022458.
1083022458
2> DateTime = calendar:gregorian_seconds_to_datetime(Seconds).
{{34,4,26},{23,34,18}}
3> {{Year, Month, Day}, {Hour, Min, Sec}} = DateTime.
{{34,4,26},{23,34,18}}
4> io:fwrite("Today's Date is ~2B/~2B/~4..0B ~2B:~2.10.0B:~2.10.0B\n",
4> [Month, Day, Year, Hour, Min, Sec]).
Today's Date is  4/26/0034 23:34:18
ok                       

In recipe TimeToday we discussed how to convert a date structure to a string. Convert in the opposite direction is also possible, and useful. Unfortunately, there is not a lot of built-in Erlang plumbing to do so. However, if we are very sure of the format we can easily extract the data we need using Erlang's ever-helpful io and io_lib modules:

5> Some_Date_String = "2004-04-26T18:26:18-0500".
"2004-04-26T18:26:18-0500".
6> {ok, [YYY,MMM,DD,HH,MM,SS,ZZ],_} = 
6> io_lib:fread("~4d-~2d-~2dT~2d:~2d:~2d-~4d", Some_Date_String).
{ok,[2004,4,26,18,26,18,500],[]}