Date and Time
DateTime class
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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.
Note
Sming uses 32-bit signed integer for its time_t data type which supports a range of +/-68 years. This means Sming is susceptible to Year 2038 problem.
Public Functions
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inline DateTime()
Instantiate an uninitialised date and time object.
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inline DateTime(time_t time)
Instantiate a date and time object from a Unix timestamp.
- Parameters
time – Unix time to assign to object
-
inline operator time_t()
Get current Unix time.
- Returns
time_t – Quantity of seconds since 00:00:00 1970-01-01
-
void setTime(time_t time)
Set time using Unix timestamp.
- Parameters
time – Unix time to set object time to
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inline void setTime(uint8_t sec, uint8_t min, uint8_t hour, uint8_t day, uint8_t month, uint16_t year)
Set time using time and date component values.
- Parameters
sec – Seconds
min – Minutes
hour – Hour
day – Day of month
month – Month (0=Jan, 11=Dec)
year – Year
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bool fromHttpDate(const String &httpDate)
Parse a HTTP full date and set time and date.
Note
Also supports obsolete RFC 850 date format, e.g. Sunday, 06-Nov-94 08:49:37 GMT where 2 digit year represents range 1970-2069
Note
GMT suffix is optional and is always assumed / ignored
- Parameters
httpDate – HTTP full date in RFC 1123 format, e.g. Sun, 06 Nov 1994 08:49:37 GMT
- Returns
bool – True on success
-
bool isNull()
Check if time date object is initialised.
- Returns
True – if object has no value. False if initialised.
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time_t toUnixTime()
Get Unix time.
Note
Unix time does not account for leap seconds. To convert Unix time to UTC requires reference to a leap second table.
- Returns
time_t – Unix time, quantity of seconds since 00:00:00 1970-01-01
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String toShortDateString()
Get human readable date.
- Returns
String – Date in requested format, e.g. DD.MM.YYYY
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String toShortTimeString(bool includeSeconds = false)
Get human readable time.
- Parameters
includeSeconds – True to include seconds (Default: false)
- Returns
String – Time in format hh:mm or hh:mm:ss
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String toFullDateTimeString()
Get human readable date and time.
- Returns
String – Date and time in format DD.MM.YYYY hh:mm:ss
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String toISO8601()
Get human readable date and time.
- Returns
String – Date and time in format YYYY-MM-DDThh:mm:ssZ
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String toHTTPDate()
Get human readable date and time.
- Returns
String – Date and time in format DDD, DD MMM YYYY hh:mm:ss GMT
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void addMilliseconds(long add)
Add time to date time object.
- Parameters
add – Quantity of milliseconds to add to object
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String format(const char *formatString)
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
- Returns
String – Formatted string
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inline String format(const String &formatString)
Create string formatted with time and date placeholders.
Note
see format(const char*) for parameter details
- Parameters
formatString – String including date and time formatting
- Returns
String – Formatted string
Public Members
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uint8_t Hour = 0
Hour (0-23)
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uint8_t Minute = 0
Minute (0-59)
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uint8_t Second = 0
Second (0-59)
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uint16_t Milliseconds = 0
Milliseconds (0-999)
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uint8_t Day = 0
Day of month (1-31)
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uint8_t DayofWeek = 0
Day of week (0-6 Sunday is day 0)
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uint16_t DayofYear = 0
Day of year (0-365)
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uint8_t Month = 0
Month (0-11 Jan is month 0)
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uint16_t Year = 0
Full Year number.
Public Static Functions
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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. To convert Unix time to UTC requires reference to a leap second table.
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
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static time_t toUnixTime(uint8_t sec, uint8_t min, uint8_t hour, uint8_t 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::convertToUnixTime(…);
Note
32-bit Unix time is valid between 1901-12-13 and 03:14:07 2038-01-19
Note
Unix time does not account for leap seconds. To convert Unix time to UTC requires reference to a leap second table.
- Parameters
sec – Seconds
min – Minutes
hour – Hours
day – Days
month – Month (0-11, Jan=0, Feb=1, …Dec=11)
year – Year (1901-2036), either full 4 digit year or 2 digits for 1970-2036
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inline DateTime()
System Clock
Enums
Variables
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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
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class SystemClockClass
- #include <SystemClock.h>
Public Functions
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time_t now(TimeZone timeType = eTZ_Local) const
Get the current date and time.
- Parameters
timeType – Time zone to use (UTC / local)
- Returns
DateTime – Current date and time
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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?
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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
- Returns
String – Current time in format:
dd.mm.yy hh:mm:ss
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bool setTimeZoneOffset(int seconds)
Sets the local time zone offset.
- Parameters
seconds – Offset from UTC of local time zone in seconds (-720 < offset < +720)
- Returns
bool – true on success, false if value out of range
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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)
- Returns
bool – true on success, false if value out of range
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inline int getTimeZoneOffset() const
Get the current time zone offset.
- Returns
int – Offset in seconds from UTC
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time_t now(TimeZone timeType = eTZ_Local) const