date_to_gregorian_days(Date)->Daysdate_to_gregorian_days(Year,Month,Day)->Days
Types:
Date = date()
Year = year()
Month = month()
Day = day()
Computes the number of gregorian days starting with year 0 and ending at the specified date.
datetime_to_gregorian_seconds(DateTime)->Seconds
Types:
DateTime = datetime()
Seconds = integer() >= 0
Computes the number of gregorian seconds starting with year 0 and ending at the specified date and
time.
day_of_the_week(Date)->daynum()day_of_the_week(Year,Month,Day)->daynum()
Types:
Date = date()
Year = year()
Month = month()
Day = day()
Computes the day of the week from the specified Year, Month, and Day. Returns the day of the week
as 1: Monday, 2: Tuesday, and so on.
gregorian_days_to_date(Days)->date()
Types:
Days = integer() >= 0
Computes the date from the specified number of gregorian days.
gregorian_seconds_to_datetime(Seconds)->datetime()
Types:
Seconds = integer() >= 0
Computes the date and time from the specified number of gregorian seconds.
is_leap_year(Year)->boolean()
Types:
Year = year()
Checks if the specified year is a leap year.
iso_week_number()->yearweeknum()
Returns tuple {Year,WeekNum} representing the ISO week number for the actual date. To determine
the actual date, use function local_time/0.
iso_week_number(Date)->yearweeknum()
Types:
Date = date()
Returns tuple {Year,WeekNum} representing the ISO week number for the specified date.
last_day_of_the_month(Year,Month)->LastDay
Types:
Year = year()
Month = month()
LastDay = ldom()
Computes the number of days in a month.
local_time()->datetime()
Returns the local time reported by the underlying operating system.
local_time_to_universal_time(DateTime1)->DateTime2
Types:
DateTime1 = DateTime2 = datetime1970()
Converts from local time to Universal Coordinated Time (UTC). DateTime1 must refer to a local date
after Jan 1, 1970.
Warning:
This function is deprecated. Use local_time_to_universal_time_dst/1 instead, as it gives a more
correct and complete result. Especially for the period that does not exist, as it is skipped
during the switch to daylight saving time, this function still returns a result.
local_time_to_universal_time_dst(DateTime1)->[DateTime]
Types:
DateTime1 = DateTime = datetime1970()
Converts from local time to Universal Coordinated Time (UTC). DateTime1 must refer to a local date
after Jan 1, 1970.
The return value is a list of 0, 1, or 2 possible UTC times:
[]:
For a local {Date1,Time1} during the period that is skipped when switching to daylight saving
time, there is no corresponding UTC, as the local time is illegal (it has never occured).
[DstDateTimeUTC,DateTimeUTC]:
For a local {Date1,Time1} during the period that is repeated when switching from daylight
saving time, two corresponding UTCs exist; one for the first instance of the period when
daylight saving time is still active, and one for the second instance.
[DateTimeUTC]:
For all other local times only one corresponding UTC exists.
now_to_datetime(Now)->datetime1970()
Types:
Now = erlang:timestamp()
Returns Universal Coordinated Time (UTC) converted from the return value from erlang:timestamp/0.
now_to_local_time(Now)->datetime1970()
Types:
Now = erlang:timestamp()
Returns local date and time converted from the return value from erlang:timestamp/0.
now_to_universal_time(Now)->datetime1970()
Types:
Now = erlang:timestamp()
Returns Universal Coordinated Time (UTC) converted from the return value from erlang:timestamp/0.
rfc3339_to_system_time(DateTimeString)->integer()rfc3339_to_system_time(DateTimeString,Options)->integer()
Types:
DateTimeString = rfc3339_string()
Options = [Option]
Option = {unit, rfc3339_time_unit()}
rfc3339_string() = [byte(), ...]
rfc3339_time_unit() =
microsecond | millisecond | nanosecond | second
Converts an RFC 3339 timestamp into system time. The data format of RFC 3339 timestamps is
described by RFC 3339.
Valid option:
{unit,Unit}:
The time unit of the return value. The default is second.
1> calendar:rfc3339_to_system_time("2018-02-01T16:17:58+01:00").
1517498278
2> calendar:rfc3339_to_system_time("2018-02-01 15:18:02.088Z", [{unit, nanosecond}]).
1517498282088000000
seconds_to_daystime(Seconds)->{Days,Time}
Types:
Seconds = Days = integer()
Time = time()
Converts a specified number of seconds into days, hours, minutes, and seconds. Time is always non-
negative, but Days is negative if argument Seconds is.
seconds_to_time(Seconds)->time()
Types:
Seconds = secs_per_day()
secs_per_day() = 0..86400
Computes the time from the specified number of seconds. Seconds must be less than the number of
seconds per day (86400).
system_time_to_local_time(Time,TimeUnit)->datetime()
Types:
Time = integer()
TimeUnit = erlang:time_unit()
Converts a specified system time into local date and time.
system_time_to_rfc3339(Time)->DateTimeStringsystem_time_to_rfc3339(Time,Options)->DateTimeString
Types:
Time = integer()
Options = [Option]
Option =
{offset, offset()} |
{time_designator, byte()} |
{unit, rfc3339_time_unit()}
DateTimeString = rfc3339_string()
offset() = [byte()] | (Time :: integer())
rfc3339_string() = [byte(), ...]
rfc3339_time_unit() =
microsecond | millisecond | nanosecond | second
Converts a system time into an RFC 3339 timestamp. The data format of RFC 3339 timestamps is
described by RFC 3339. The data format of offsets is also described by RFC 3339.
Valid options:
{offset,Offset}:
The offset, either a string or an integer, to be included in the formatted string. An empty
string, which is the default, is interpreted as local time. A non-empty string is included as
is. The time unit of the integer is the same as the one of Time.
{time_designator,Character}:
The character used as time designator, that is, the date and time separator. The default is
$T.
{unit,Unit}:
The time unit of Time. The default is second. If some other unit is given (millisecond,
microsecond, or nanosecond), the formatted string includes a fraction of a second. The number
of fractional second digits is three, six, or nine depending on what time unit is chosen.
Notice that trailing zeros are not removed from the fraction.
1> calendar:system_time_to_rfc3339(erlang:system_time(second)).
"2018-04-23T14:56:28+02:00"
2> calendar:system_time_to_rfc3339(erlang:system_time(second), [{offset, "-02:00"}]).
"2018-04-23T10:56:52-02:00"
3> calendar:system_time_to_rfc3339(erlang:system_time(second), [{offset, -7200}]).
"2018-04-23T10:57:05-02:00"
4> calendar:system_time_to_rfc3339(erlang:system_time(millisecond), [{unit, millisecond}, {time_designator, $\s}, {offset, "Z"}]).
"2018-04-23 12:57:20.482Z"
system_time_to_universal_time(Time,TimeUnit)->datetime()
Types:
Time = integer()
TimeUnit = erlang:time_unit()
Converts a specified system time into universal date and time.
time_difference(T1,T2)->{Days,Time}
Types:
T1 = T2 = datetime()
Days = integer()
Time = time()
Returns the difference between two {Date,Time} tuples. T2 is to refer to an epoch later than T1.
Warning:
This function is obsolete. Use the conversion functions for gregorian days and seconds instead.
time_to_seconds(Time)->secs_per_day()
Types:
Time = time()
secs_per_day() = 0..86400
Returns the number of seconds since midnight up to the specified time.
universal_time()->datetime()
Returns the Universal Coordinated Time (UTC) reported by the underlying operating system. Returns
local time if universal time is unavailable.
universal_time_to_local_time(DateTime)->datetime()
Types:
DateTime = datetime1970()
Converts from Universal Coordinated Time (UTC) to local time. DateTime must refer to a date after
Jan 1, 1970.
valid_date(Date)->boolean()valid_date(Year,Month,Day)->boolean()
Types:
Date = date()
Year = Month = Day = integer()
This function checks if a date is a valid.
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