Date and Time

DateTime class

class DateTime

Date and time class.

Date and time functions mostly work with Unix time, the quantity of seconds since 00:00:00 1970-01-01. There is no support for leap seconds which are added (and in theory, removed) occasionally to compensate for earth rotation variation. This means that timespan calculation and free-running clocks may be inaccurate if they span leap seconds. To facilitate leap seconds, reference must be made to leap second table. This will not be done within the Sming framework and must be handled by application code if required.

32-bit signed values support a range of +/-68 years; the Unix epoch is midnight 1 Jan 1970, so overflows at about 3am on 19 Jan 2038. The value is signed which allows dates prior to 1970 to be represented.

Acceptable date formats:

YYYY-MM-DD or YYYYMMDD
YYYY-MM (but not YYYYMM)

Acceptable time formats:

Thh:mm:ss.sss or Thhmmss.sss
Thh:mm:ss or Thhmmss
Thh:mm.mmm or Thhmm.mmm
Thh:mm or Thhmm
Thh.hhh
Thh

Parameters:: datetime – Date and optional time in ISO8601 format, e.g. “1994-11-06”, “1994-11-06T08:49:37”. Separators are optional.
Return values:: bool – True on success

bool isNull() const

Check if time date object is initialised.

Return values:: True – if object has no value. False if initialised.

time_t toUnixTime() const

Get Unix time.

Note

Unix time does not account for leap seconds.

Return values:: time_t – Unix time, quantity of seconds since 00:00:00 1970-01-01

String toShortDateString() const

Get human readable date.

Return values:: String – Date in requested format, e.g. DD.MM.YYYY

String toShortTimeString(bool includeSeconds = false) const

Get human readable time.

Parameters:: includeSeconds – True to include seconds (Default: false)
Return values:: String – Time in format hh:mm or hh:mm:ss

String toFullDateTimeString() const

Get human readable date and time.

Return values:: String – Date and time in format DD.MM.YYYY hh:mm:ss

String toISO8601() const

Get human readable date and time.

Return values:: String – Date and time in format YYYY-MM-DDThh:mm:ssZ

String toHTTPDate() const

Get human readable date and time.

Return values:: String – Date and time in format DDD, DD MMM YYYY hh:mm:ss GMT

void addMilliseconds(long add)

Add time to date time object.

Parameters:: add – Quantity of milliseconds to add to object

String format(const char *formatString) const

Create string formatted with time and date placeholders.

Note

Uses strftime style formatting, e.g. format(“Today is %a, %d %b %Y”) returns “Today is Mon, 10 Dec 2018”

Note

Localisation may be implemented in libsming at compile time by setting LOCALE, e.g. LOCALE=LOCALE_DE_DE

Note

Default localisation is EN_GB

Note

Formatting parameters

Param	Description	Locale
%a	Abbreviated weekday name	*
%A	Full weekday name	*
%b	Abbreviated month name	*
%B	Full month name	*
%c	Locale preferred date and time format	*
%C	Century number (2 digits)
%d	Day of month as decimal number with leading zero (2 digits)
%D	US date format (mm/dd/yyyy)
%e	Day of month as decimal number with leading space (2 digits)
%F	ISO 8601 date format (YYYY-mm-dd)
%h	Equivalent to %b	*
%H	Hour as a decimal number using a 24-hour clock (range 00 to 23)
%I	Hour as a decimal number using a 12-hour clock (range 00 to 12)
%j	Day of the year as a decimal number (range 001 to 366)
%m	Month as a decimal number (range 01 to 12)
%M	Minute as a decimal number (range 00 to 59)
%n	Newline
%p	Meridiem indicator: AM or PM. Midnight is AM and noon is PM
%r	Locale 12-hour clock time notation. This is equivalent to %I:%M:%S %p	*
%R	Time in 24-hour notation (HH:MM)
%S	Second as a decimal number (range 00 to 60)
%t	Horizontal tab
%T	Time in 24-hour notation (HH:MM:SS)
%u	Day of the week as a decimal (range 1 to 7, Monday is 1)
%U	Week number as a decimal number (range 00 to 53, first Sunday as the first day of week 01)
%V	ISO 8601 week number as a decimal number (range 01 to 53, where week 1 is the first week including a Thursday)
%w	Day of the week as a decimal (range 0 to 6, Sunday is 0)
%W	Week number as a decimal number (range 00 to 53, first Monday as the first day of week 01)
%x	Locale preferred date representation	*
%X	Locale preferred time representation	*
%y	Year as a decimal number without a century (range 00 to 99)
%Y	Year as a decimal number (range 1970 to …)
%%	Percent sign

Parameters:: formatString – String including date and time formatting
Return values:: String – Formatted string

inline String format(const String &formatString) const

Create string formatted with time and date placeholders.

Note

see format(const char*) for parameter details

Parameters:: formatString – String including date and time formatting
Return values:: String – Formatted string

Public Members

uint8_t Hour = 0: Hour (0-23)

uint8_t Minute = 0: Minute (0-59)

uint8_t Second = 0: Second (0-59)

uint16_t Milliseconds = 0: Milliseconds (0-999)

uint8_t Day = 0: Day of month (1-31)

uint8_t DayofWeek = 0: Day of week (0-6 Sunday is day 0)

uint16_t DayofYear = 0: Day of year (0-365)

uint8_t Month = 0: Month (0-11 Jan is month 0)

uint16_t Year = 0: Full Year number.

Public Static Functions

static void fromUnixTime(time_t timep, uint8_t *psec, uint8_t *pmin, uint8_t *phour, uint8_t *pday, uint8_t *pwday, uint8_t *pmonth, uint16_t *pyear)

Convert from Unix time to individual time components.

Note

This is a more compact version of the C library localtime function

Note

Pass the Unix timedate value and pointers to existing integers. The integers are updated with the converted values

Note

This static function may be used without instantiating a DateTime object, e.g. DateTime::convertFromUnixTime(…);

Note

32-bit Unix time has year 2036 issue.

Note

Unix time does not account for leap seconds.

Note

All of the return values are optional, specify nullptr if not required

Parameters:

timep – Unix time date value to convert
psec – Pointer to integer to hold resulting seconds
pmin – Pointer to integer to hold resulting minutes
phour – Pointer to integer to hold resulting hour
pday – Pointer to integer to hold resulting day of month
pwday – Pointer to integer to hold resulting day of week
pmonth – Pointer to integer to hold resulting month
pyear – Pointer to integer to hold resulting year

static time_t toUnixTime(int sec, int min, int hour, int day, uint8_t month, uint16_t year)

Convert from individual time components to Unix time.

Note

Seconds, minutes, hours and days may be any value, e.g. to calculate the value for 300 days since 1970 (epoch), set day=300

Note

This static function may be used without instantiating a DateTime object, e.g. time_t unixTime = DateTime::toUnixTime(...);

Note

Unix time does not account for leap seconds.

Parameters:

sec – Seconds
min – Minutes
hour – Hours
day – Days
month – Month (0-11, Jan=0, Feb=1, …Dec=11), or enum (dtJanuary, …)
year – Year, either full 4 digit year or 2 digits for 2000-2068

Return values:

time_t – Number of seconds since unix epoch (Midnight, Jan 1 1970)

System Clock

Enums

enum TimeZone

Time zones.

Values:

enumerator eTZ_UTC: Use universal time coordinate (UTC)

enumerator eTZ_Local: Use local time.

Variables

SystemClockClass SystemClock

Global instance of system clock object.

Note

Use SystemClock.function to access system clock functions

Note

Example:

SystemClock.setTimeZone(+9.5); //Darwin, Australia

class SystemClockClass

#include <SystemClock.h>

Public Functions

time_t now(TimeZone timeType = eTZ_Local) const

Get the current date and time.

Parameters:: timeType – Time zone to use (UTC / local)
Return values:: DateTime – Current date and time

bool setTime(time_t time, TimeZone timeType)

Set the system clock’s time.

Note

System time is always stored as UTC time. If setting using the value retrieved from a time server using NTP, specify eTZ_UTC. If passing a local value using eTZ_Local, ensure that the time zone has been set correctly as it will be converted to UTC before storing.

Parameters:

time – Unix time to set clock to (quantity of seconds since 00:00:00 1970-01-01)
timeType – Time zone of Unix time, i.e. is time provided as local or UTC?

String getSystemTimeString(TimeZone timeType = eTZ_Local) const

Get current time as a string.

Note

Date separator may be changed by adding #define DT_DATE_SEPARATOR "/" to source code

Parameters:: timeType – Time zone to present time as, i.e. return local or UTC time
Return values:: String – Current time in format: dd.mm.yy hh:mm:ss

bool setTimeZoneOffset(int seconds)

Sets the local time zone offset.

Parameters:: seconds – Offset from UTC of local time zone in seconds (-720 < offset < +720)
Return values:: bool – true on success, false if value out of range

inline bool setTimeZone(float localTimezoneOffset)

Set the local time zone offset in hours.

Parameters:: localTimezoneOffset – Offset from UTC of local time zone in hours (-12.0 < offset < +12.0)
Return values:: bool – true on success, false if value out of range

inline int getTimeZoneOffset() const

Get the current time zone offset.

Return values:: int – Offset in seconds from UTC

inline bool isSet() const: Determine if setTime() has been called yet.

Note

Indicates whether time returned can be relied upon

Private Members

int timeZoneOffsetSecs = 0

bool timeSet = false