glibmm: Glib::DateTime Class Reference

glibmm 2.66.2

Public Member Functions | Static Public Member Functions | Protected Attributes | Related Functions | List of all members
Glib::DateTime Class Reference

DateTime - A structure representing Date and Time. More...

`#include <glibmm/datetime.h>`

## Public Member Functions
| DateTime ()
| Constructs an invalid object. More...
| DateTime (GDateTime * castitem, bool make_a_copy=false)
| DateTime (const DateTime & src)
DateTime & | operator= (const DateTime & src)
| DateTime (DateTime && other) noexcept
DateTime & | operator= (DateTime && other) noexcept
| ~DateTime () noexcept
void | swap (DateTime & other) noexcept
GDateTime * | gobj ()
const GDateTime * | gobj () const
GDateTime * | gobj_copy () const
| Provides access to the underlying C instance. The caller is responsible for freeing it. Use when directly setting fields in structs. More...
| operator bool () const
| Returns true if the DateTime object is valid. More...
DateTime | add (TimeSpan timespan) const
| Creates a copy of datetime and adds the specified timespan to the copy. More...
DateTime | add_years (int years) const
| Creates a copy of datetime and adds the specified number of years to the copy. More...
DateTime | add_months (int months) const
| Creates a copy of datetime and adds the specified number of months to the copy. More...
DateTime | add_weeks (int weeks) const
| Creates a copy of datetime and adds the specified number of weeks to the copy. More...
DateTime | add_days (int days) const
| Creates a copy of datetime and adds the specified number of days to the copy. More...
DateTime | add_hours (int hours) const
| Creates a copy of datetime and adds the specified number of hours. More...
DateTime | add_minutes (int minutes) const
| Creates a copy of datetime adding the specified number of minutes. More...
DateTime | add_seconds (double seconds) const
| Creates a copy of datetime and adds the specified number of seconds. More...
DateTime | add_full (int years, int months, int days, int hours, int minutes, double seconds) const
| Creates a new DateTime adding the specified values to the current date and time in datetime. More...
TimeSpan | difference (const DateTime & other) const
| Calculates the difference in time between *this and other. More...
int | compare (const DateTime & other) const
| A comparison function for DateTimes that is suitable as a CompareFunc. More...
guint | hash () const
| Hashes datetime into a `unsigned int`, suitable for use within HashTable. More...
bool | equal (const DateTime & other) const
| Checks to see if *this and other are equal. More...
void | get_ymd (int & year, int & month, int & day) const
| Retrieves the Gregorian day, month, and year of a given DateTime. More...
int | get_year () const
| Retrieves the year represented by datetime in the Gregorian calendar. More...
int | get_month () const
| Retrieves the month of the year represented by datetime in the Gregorian calendar. More...
int | get_day_of_month () const
| Retrieves the day of the month represented by datetime in the gregorian calendar. More...
int | get_week_numbering_year () const
| Returns the ISO 8601 week-numbering year in which the week containing datetime falls. More...
int | get_week_of_year () const
| Returns the ISO 8601 week number for the week containing datetime. More...
int | get_day_of_week () const
| Retrieves the ISO 8601 day of the week on which datetime falls (1 is Monday, 2 is Tuesday... More...
int | get_day_of_year () const
| Retrieves the day of the year represented by datetime in the Gregorian calendar. More...
int | get_hour () const
| Retrieves the hour of the day represented by datetime. More...
int | get_minute () const
| Retrieves the minute of the hour represented by datetime. More...
int | get_second () const
| Retrieves the second of the minute represented by datetime. More...
int | get_microsecond () const
| Retrieves the microsecond of the date represented by datetime. More...
double | get_seconds () const
| Retrieves the number of seconds since the start of the last minute, including the fractional part. More...
gint64 | to_unix () const
| Gives the Unix time corresponding to datetime, rounding down to the nearest second. More...
bool | to_timeval (TimeVal & tv) const
| Stores the instant in time that datetime represents into tv. More...
TimeSpan | get_utc_offset () const
| Determines the offset to UTC in effect at the time and in the time zone of datetime. More...
TimeZone | get_timezone () const
| Get the time zone for this datetime. More...
Glib::ustring | get_timezone_abbreviation () const
| Determines the time zone abbreviation to be used at the time and in the time zone of datetime. More...
bool | is_daylight_savings () const
| Determines if daylight savings time is in effect at the time and in the time zone of datetime. More...
DateTime | to_timezone (const TimeZone & tz) const
| Create a new DateTime corresponding to the same instant in time as datetime, but in the time zone tz. More...
DateTime | to_local () const
| Creates a new DateTime corresponding to the same instant in time as datetime, but in the local time zone. More...
DateTime | to_utc () const
| Creates a new DateTime corresponding to the same instant in time as datetime, but in UTC. More...
Glib::ustring | format (const Glib::ustring & format_str) const
| Creates a newly allocated string representing the requested format_str. More...
Glib::ustring | format_iso8601 () const
| Format datetime in ISO 8601 format, including the date, time and time zone, and return that as a UTF-8 encoded string. More...

## Static Public Member Functions
static DateTime | create_now (const TimeZone & tz)
| Creates a DateTime corresponding to this exact instant in the given time zone tz. More...
static DateTime | create_now_local ()
| Creates a DateTime corresponding to this exact instant in the local time zone. More...
static DateTime | create_now_utc ()
| Creates a DateTime corresponding to this exact instant in UTC. More...
static DateTime | create_now_local (gint64 t)
| Creates a DateTime corresponding to the given Unix time t in the local time zone. More...
static DateTime | create_now_utc (gint64 t)
| Creates a DateTime corresponding to the given Unix time t in UTC. More...
static DateTime | create_now_local (const TimeVal & tv)
| Creates a DateTime corresponding to the given TimeVal tv in the local time zone. More...
static DateTime | create_now_utc (const TimeVal & tv)
| Creates a DateTime corresponding to the given TimeVal tv in UTC. More...
static DateTime | create_from_iso8601 (const Glib::ustring & text, const TimeZone & default_tz)
| Creates a DateTime corresponding to the given ISO 8601 formatted string text. More...
static DateTime | create_from_iso8601 (const Glib::ustring & text)
| A create_from_iso8601() convenience overload. More...
static DateTime | create (const TimeZone & tz, int year, int month, int day, int hour, int minute, double seconds)
| Creates a new DateTime corresponding to the given date and time in the time zone tz. More...
static DateTime | create_local (int year, int month, int day, int hour, int minute, double seconds)
| Creates a new DateTime corresponding to the given date and time in the local time zone. More...
static DateTime | create_utc (int year, int month, int day, int hour, int minute, double seconds)
| Creates a new DateTime corresponding to the given date and time in UTC. More...

## Protected Attributes
GDateTime * | gobject_

## Related Functions
(Note that these are not member functions.)
void | swap (DateTime & lhs, DateTime & rhs) noexcept
Glib::DateTime | wrap (GDateTime * object, bool take_copy=false)
| A Glib::wrap() method for this object. More...

## Detailed Description

DateTime - A structure representing Date and Time.

DateTime is a structure that combines a Gregorian date and time into a single structure. It provides many conversion and methods to manipulate dates and times. Time precision is provided down to microseconds and the time can range (proleptically) from 0001-01-01 00:00:00 to 9999-12-31 23:59:59.999999. DateTime follows POSIX time in the sense that it is oblivious to leap seconds.

DateTime is an immutable object; once it has been created it cannot be modified further. All modifiers will create a new DateTime. Nearly all such functions can fail due to the date or time going out of range, in which case `0` will be returned.

Many parts of the API may produce non-obvious results. As an example, adding two months to January 31st will yield March 31st whereas adding one month and then one month again will yield either March 28th or March 29th. Also note that adding 24 hours is not always the same as adding one day (since days containing daylight savings time transitions are either 23 or 25 hours in length).

Since glibmm 2.30:

## Constructor & Destructor Documentation

## ◆ DateTime() [1/4]

Glib::DateTime::DateTime | ( |  | ) |

Constructs an invalid object.

E.g. for output arguments to methods. There is not much you can do with the object before it has been assigned a valid value.

## ◆ DateTime() [2/4]

Glib::DateTime::DateTime | ( | GDateTime * | castitem,
|  | bool | make_a_copy = `false`
| ) |  |
| explicit

## ◆ DateTime() [3/4]

Glib::DateTime::DateTime | ( | const DateTime & | src | ) |

## ◆ DateTime() [4/4]

Glib::DateTime::DateTime | ( | DateTime && | other | ) |
| noexcept

## ◆ ~DateTime()

Glib::DateTime::~DateTime | ( |  | ) |
| noexcept

## Member Function Documentation

## ◆ add()

DateTime Glib::DateTime::add | ( | TimeSpan | timespan | ) | const

Creates a copy of datetime and adds the specified timespan to the copy.

Since glibmm 2.26:

Parameters

  timespan | A TimeSpan.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ add_days()

DateTime Glib::DateTime::add_days | ( | int | days | ) | const

Creates a copy of datetime and adds the specified number of days to the copy.

Add negative values to subtract days.

Since glibmm 2.26:

Parameters

  days | The number of days.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ add_full()

DateTime Glib::DateTime::add_full | ( | int | years,
|  | int | months,
|  | int | days,
|  | int | hours,
|  | int | minutes,
|  | double | seconds
| ) |  | const

Creates a new DateTime adding the specified values to the current date and time in datetime.

Add negative values to subtract.

Since glibmm 2.26:

Parameters

  years | The number of years to add.
  months | The number of months to add.
  days | The number of days to add.
  hours | The number of hours to add.
  minutes | The number of minutes to add.
  seconds | The number of seconds to add.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ add_hours()

DateTime Glib::DateTime::add_hours | ( | int | hours | ) | const

Creates a copy of datetime and adds the specified number of hours.

Add negative values to subtract hours.

Since glibmm 2.26:

Parameters

  hours | The number of hours to add.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ add_minutes()

DateTime Glib::DateTime::add_minutes | ( | int | minutes | ) | const

Creates a copy of datetime adding the specified number of minutes.

Add negative values to subtract minutes.

Since glibmm 2.26:

Parameters

  minutes | The number of minutes to add.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ add_months()

DateTime Glib::DateTime::add_months | ( | int | months | ) | const

Creates a copy of datetime and adds the specified number of months to the copy.

Add negative values to subtract months.

The day of the month of the resulting DateTime is clamped to the number of days in the updated calendar month. For example, if adding 1 month to 31st January 2018, the result would be 28th February 2018. In 2020 (a leap year), the result would be 29th February.

Since glibmm 2.26:

Parameters

  months | The number of months.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ add_seconds()

DateTime Glib::DateTime::add_seconds | ( | double | seconds | ) | const

Creates a copy of datetime and adds the specified number of seconds.

Add negative values to subtract seconds.

Since glibmm 2.26:

Parameters

  seconds | The number of seconds to add.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ add_weeks()

DateTime Glib::DateTime::add_weeks | ( | int | weeks | ) | const

Creates a copy of datetime and adds the specified number of weeks to the copy.

Add negative values to subtract weeks.

Since glibmm 2.26:

Parameters

  weeks | The number of weeks.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ add_years()

DateTime Glib::DateTime::add_years | ( | int | years | ) | const

Creates a copy of datetime and adds the specified number of years to the copy.

Add negative values to subtract years.

As with g_date_time_add_months(), if the resulting date would be 29th February on a non-leap year, the day will be clamped to 28th February.

Since glibmm 2.26:

Parameters

  years | The number of years.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ compare()

int Glib::DateTime::compare | ( | const DateTime & | other | ) | const

A comparison function for DateTimes that is suitable as a CompareFunc.

Since glibmm 2.26:

Parameters

  other | The DateTime to compare with.

Returns
  -1, 0 or 1 if *this is less than, equal to or greater than other.

## ◆ create()

static DateTime Glib::DateTime::create | ( | const TimeZone & | tz,
|  | int | year,
|  | int | month,
|  | int | day,
|  | int | hour,
|  | int | minute,
|  | double | seconds
| ) |  |
| static

Creates a new DateTime corresponding to the given date and time in the time zone tz.

The year must be between 1 and 9999, month between 1 and 12 and day between 1 and 28, 29, 30 or 31 depending on the month and the year.

hour must be between 0 and 23 and minute must be between 0 and 59.

seconds must be at least 0.0 and must be strictly less than 60.0. It will be rounded down to the nearest microsecond.

If the given time is not representable in the given time zone (for example, 02:30 on March 14th 2010 in Toronto, due to daylight savings time) then the time will be rounded up to the nearest existing time (in this case, 03:00). If this matters to you then you should verify the return value for containing the same as the numbers you gave.

In the case that the given time is ambiguous in the given time zone (for example, 01:30 on November 7th 2010 in Toronto, due to daylight savings time) then the time falling within standard (ie: non-daylight) time is taken.

It not considered a programmer error for the values to this function to be out of range, but in the case that they are, the function will return `nullptr`.

You should release the return value by calling g_date_time_unref() when you are done with it.

Since glibmm 2.26:

Parameters

  tz | A TimeZone.
  year | The year component of the date.
  month | The month component of the date.
  day | The day component of the date.
  hour | The hour component of the date.
  minute | The minute component of the date.
  seconds | The number of seconds past the minute.

Returns
  A new DateTime, or `nullptr`.

## ◆ create_from_iso8601() [1/2]

static DateTime Glib::DateTime::create_from_iso8601 | ( | const Glib::ustring & | text | ) |
| static

A create_from_iso8601() convenience overload.

## ◆ create_from_iso8601() [2/2]

static DateTime Glib::DateTime::create_from_iso8601 | ( | const Glib::ustring & | text,
|  | const TimeZone & | default_tz
| ) |  |
| static

Creates a DateTime corresponding to the given ISO 8601 formatted string text.

ISO 8601 strings of the form <date><sep><time><tz> are supported, with some extensions from RFC 3339 as mentioned below.

Note that as DateTime "is oblivious to leap seconds", leap seconds information in an ISO-8601 string will be ignored, so a `23:59:60` time would be parsed as `23:59:59`.

<sep> is the separator and can be either 'T', 't' or ' '. The latter two separators are an extension from RFC 3339.

<date> is in the form:

- `YYYY-MM-DD` - Year/month/day, e.g. 2016-08-24.
- `YYYYMMDD` - Same as above without dividers.
- `YYYY-DDD` - Ordinal day where DDD is from 001 to 366, e.g. 2016-237.
- `YYYYDDD` - Same as above without dividers.
- `YYYY-Www-D` - Week day where ww is from 01 to 52 and D from 1-7, e.g. 2016-W34-3.
- `YYYYWwwD` - Same as above without dividers.

<time> is in the form:

- `hh:mm:ss(.sss)` - Hours, minutes, seconds (subseconds), e.g. 22:10:42.123.
- `hhmmss(.sss)` - Same as above without dividers.

<tz> is an optional timezone suffix of the form:

- `Z` - UTC.
- `+hh:mm` or `-hh:mm` - Offset from UTC in hours and minutes, e.g. +12:00.
- `+hh` or `-hh` - Offset from UTC in hours, e.g. +12.

If the timezone is not provided in text it must be provided in default_tz (this field is otherwise ignored).

This call can fail (returning `nullptr`) if text is not a valid ISO 8601 formatted string.

You should release the return value by calling g_date_time_unref() when you are done with it.

Since glibmm 2.62:

Parameters

  text | An ISO 8601 formatted time string.
  default_tz | A TimeZone to use if the text doesn't contain a timezone, or `nullptr`.

Returns
  A new DateTime, or `nullptr`.

## ◆ create_local()

static DateTime Glib::DateTime::create_local | ( | int | year,
|  | int | month,
|  | int | day,
|  | int | hour,
|  | int | minute,
|  | double | seconds
| ) |  |
| static

Creates a new DateTime corresponding to the given date and time in the local time zone.

This call is equivalent to calling g_date_time_new() with the time zone returned by g_time_zone_new_local().

Since glibmm 2.26:

Parameters

  year | The year component of the date.
  month | The month component of the date.
  day | The day component of the date.
  hour | The hour component of the date.
  minute | The minute component of the date.
  seconds | The number of seconds past the minute.

Returns
  A DateTime, or `nullptr`.

## ◆ create_now()

static DateTime Glib::DateTime::create_now | ( | const TimeZone & | tz | ) |
| static

Creates a DateTime corresponding to this exact instant in the given time zone tz.

The time is as accurate as the system allows, to a maximum accuracy of 1 microsecond.

This function will always succeed unless GLib is still being used after the year 9999.

You should release the return value by calling g_date_time_unref() when you are done with it.

Since glibmm 2.26:

Parameters

  tz | A TimeZone.

Returns
  A new DateTime, or `nullptr`.

## ◆ create_now_local() [1/3]

static DateTime Glib::DateTime::create_now_local | ( |  | ) |
| static

Creates a DateTime corresponding to this exact instant in the local time zone.

This is equivalent to calling g_date_time_new_now() with the time zone returned by g_time_zone_new_local().

Since glibmm 2.26:

Returns
  A new DateTime, or `nullptr`.

## ◆ create_now_local() [2/3]

static DateTime Glib::DateTime::create_now_local | ( | const TimeVal & | tv | ) |
| static

Creates a DateTime corresponding to the given TimeVal tv in the local time zone.

The time contained in a TimeVal is always stored in the form of seconds elapsed since 1970-01-01 00:00:00 UTC, regardless of the local time offset.

This call can fail (returning `nullptr`) if tv represents a time outside of the supported range of DateTime.

You should release the return value by calling g_date_time_unref() when you are done with it.

Since glibmm 2.26:
  Deprecated: 2.62: TimeVal is not year-2038-safe. Use g_date_time_new_from_unix_local() instead.

Deprecated:
  Use create_now_local(gint64 t) instead.

Parameters

  tv | A TimeVal.

Returns
  A new DateTime, or `nullptr`.

## ◆ create_now_local() [3/3]

static DateTime Glib::DateTime::create_now_local | ( | gint64 | t | ) |
| static

Creates a DateTime corresponding to the given Unix time t in the local time zone.

Unix time is the number of seconds that have elapsed since 1970-01-01 00:00:00 UTC, regardless of the local time offset.

This call can fail (returning `nullptr`) if t represents a time outside of the supported range of DateTime.

You should release the return value by calling g_date_time_unref() when you are done with it.

Since glibmm 2.26:

Parameters

  t | The Unix time.

Returns
  A new DateTime, or `nullptr`.

## ◆ create_now_utc() [1/3]

static DateTime Glib::DateTime::create_now_utc | ( |  | ) |
| static

Creates a DateTime corresponding to this exact instant in UTC.

This is equivalent to calling g_date_time_new_now() with the time zone returned by g_time_zone_new_utc().

Since glibmm 2.26:

Returns
  A new DateTime, or `nullptr`.

## ◆ create_now_utc() [2/3]

static DateTime Glib::DateTime::create_now_utc | ( | const TimeVal & | tv | ) |
| static

Creates a DateTime corresponding to the given TimeVal tv in UTC.

The time contained in a TimeVal is always stored in the form of seconds elapsed since 1970-01-01 00:00:00 UTC.

This call can fail (returning `nullptr`) if tv represents a time outside of the supported range of DateTime.

You should release the return value by calling g_date_time_unref() when you are done with it.

Since glibmm 2.26:
  Deprecated: 2.62: TimeVal is not year-2038-safe. Use g_date_time_new_from_unix_utc() instead.

Deprecated:
  Use create_now_utc(gint64 t) instead.

Parameters

  tv | A TimeVal.

Returns
  A new DateTime, or `nullptr`.

## ◆ create_now_utc() [3/3]

static DateTime Glib::DateTime::create_now_utc | ( | gint64 | t | ) |
| static

Creates a DateTime corresponding to the given Unix time t in UTC.

Unix time is the number of seconds that have elapsed since 1970-01-01 00:00:00 UTC.

This call can fail (returning `nullptr`) if t represents a time outside of the supported range of DateTime.

You should release the return value by calling g_date_time_unref() when you are done with it.

Since glibmm 2.26:

Parameters

  t | The Unix time.

Returns
  A new DateTime, or `nullptr`.

## ◆ create_utc()

static DateTime Glib::DateTime::create_utc | ( | int | year,
|  | int | month,
|  | int | day,
|  | int | hour,
|  | int | minute,
|  | double | seconds
| ) |  |
| static

Creates a new DateTime corresponding to the given date and time in UTC.

This call is equivalent to calling g_date_time_new() with the time zone returned by g_time_zone_new_utc().

Since glibmm 2.26:

Parameters

  year | The year component of the date.
  month | The month component of the date.
  day | The day component of the date.
  hour | The hour component of the date.
  minute | The minute component of the date.
  seconds | The number of seconds past the minute.

Returns
  A DateTime, or `nullptr`.

## ◆ difference()

TimeSpan Glib::DateTime::difference | ( | const DateTime & | other | ) | const

Calculates the difference in time between *this and other.

The TimeSpan that is returned is effectively *this - other.

Since glibmm 2.26:

Parameters

  other | The other DateTime.

Returns
  The difference between the two DateTime, as a time span expressed in microseconds.

## ◆ equal()

bool Glib::DateTime::equal | ( | const DateTime & | other | ) | const

Checks to see if *this and other are equal.

Equal here means that they represent the same moment after converting them to the same time zone.

Since glibmm 2.26:

Parameters

  other | The DateTime to compare with.

Returns
  `true` if *this and other are equal.

## ◆ format()

Glib::ustring Glib::DateTime::format | ( | const Glib::ustring & | format_str | ) | const

Creates a newly allocated string representing the requested format_str.

The format strings understood by this function are a subset of the strftime() format language as specified by C99. The \D, \U and \W conversions are not supported, nor is the 'E' modifier. The GNU extensions \k, \l, \s and \P are supported, however, as are the '0', '_' and '-' modifiers. The Python extension \f is also supported.

In contrast to strftime(), this function always produces a UTF-8 string, regardless of the current locale. Note that the rendering of many formats is locale-dependent and may not match the strftime() output exactly.

The following format specifiers are supported:

- \a: the abbreviated weekday name according to the current locale
- \A: the full weekday name according to the current locale
- \b: the abbreviated month name according to the current locale
- \B: the full month name according to the current locale
- \c: the preferred date and time representation for the current locale
- \C: the century number (year/100) as a 2-digit integer (00-99)
- \d: the day of the month as a decimal number (range 01 to 31)
- \e: the day of the month as a decimal number (range 1 to 31)
- \F: equivalent to `Y-m-d` (the ISO 8601 date format)
- \g: the last two digits of the ISO 8601 week-based year as a decimal number (00-99). This works well with \V and \u.
- \G: the ISO 8601 week-based year as a decimal number. This works well with \V and \u.
- \h: equivalent to \b
- \H: the hour as a decimal number using a 24-hour clock (range 00 to 23)
- \I: the hour as a decimal number using a 12-hour clock (range 01 to 12)
- \j: the day of the year as a decimal number (range 001 to 366)
- \k: the hour (24-hour clock) as a decimal number (range 0 to 23); single digits are preceded by a blank
- \l: the hour (12-hour clock) as a decimal number (range 1 to 12); single digits are preceded by a blank
- \m: the month as a decimal number (range 01 to 12)
- \M: the minute as a decimal number (range 00 to 59)
- \f: the microsecond as a decimal number (range 000000 to 999999)
- \p: either "AM" or "PM" according to the given time value, or the corresponding strings for the current locale. Noon is treated as "PM" and midnight as "AM". Use of this format specifier is discouraged, as many locales have no concept of AM/PM formatting. Use \c or \X instead.
- \P: like \p but lowercase: "am" or "pm" or a corresponding string for the current locale. Use of this format specifier is discouraged, as many locales have no concept of AM/PM formatting. Use \c or \X instead.
- \r: the time in a.m. or p.m. notation. Use of this format specifier is discouraged, as many locales have no concept of AM/PM formatting. Use \c or \X instead.
- \R: the time in 24-hour notation (\H:\M)
- \s: the number of seconds since the Epoch, that is, since 1970-01-01 00:00:00 UTC
- \S: the second as a decimal number (range 00 to 60)
- \t: a tab character
- \T: the time in 24-hour notation with seconds (\H:\M:\S)
- \u: the ISO 8601 standard day of the week as a decimal, range 1 to 7, Monday being 1. This works well with \G and \V.
- \V: the ISO 8601 standard week number of the current year as a decimal number, range 01 to 53, where week 1 is the first week that has at least 4 days in the new year. See g_date_time_get_week_of_year(). This works well with \G and \u.
- \w: the day of the week as a decimal, range 0 to 6, Sunday being 0. This is not the ISO 8601 standard format – use \u instead.
- \x: the preferred date representation for the current locale without the time
- \X: the preferred time representation for the current locale without the date
- \y: the year as a decimal number without the century
- \Y: the year as a decimal number including the century
- \z: the time zone as an offset from UTC (+hhmm)
- \%:z: the time zone as an offset from UTC (+hh:mm). This is a gnulib strftime() extension. Since: 2.38
- \%::z: the time zone as an offset from UTC (+hh:mm:ss). This is a gnulib strftime() extension. Since: 2.38
- \%:::z: the time zone as an offset from UTC, with : to necessary precision (e.g., -04, +05:30). This is a gnulib strftime() extension. Since: 2.38
- \Z: the time zone or name or abbreviation
- \%\%: a literal \% character

Some conversion specifications can be modified by preceding the conversion specifier by one or more modifier characters. The following modifiers are supported for many of the numeric conversions:

- O: Use alternative numeric symbols, if the current locale supports those.
- _: Pad a numeric result with spaces. This overrides the default padding for the specifier.
- -: Do not pad a numeric result. This overrides the default padding for the specifier.
- 0: Pad a numeric result with zeros. This overrides the default padding for the specifier.

Additionally, when O is used with B, b, or h, it produces the alternative form of a month name. The alternative form should be used when the month name is used without a day number (e.g., standalone). It is required in some languages (Baltic, Slavic, Greek, and more) due to their grammatical rules. For other languages there is no difference. \OB is a GNU and BSD strftime() extension expected to be added to the future POSIX specification, \Ob and \Oh are GNU strftime() extensions.

Since glibmm 2.56:

Since glibmm 2.26:

Parameters

  format_str | A valid UTF-8 string, containing the format for the DateTime.

Returns
  A newly allocated string formatted to the requested format or `nullptr` in the case that there was an error (such as a format specifier not being supported in the current locale).

## ◆ format_iso8601()

Glib::ustring Glib::DateTime::format_iso8601 | ( |  | ) | const

Format datetime in ISO 8601 format, including the date, time and time zone, and return that as a UTF-8 encoded string.

Since GLib 2.66, this will output to sub-second precision if needed.

Since glibmm 2.62:

Returns
  A newly allocated string formatted in ISO 8601 format or `nullptr` in the case that there was an error.

## ◆ get_day_of_month()

int Glib::DateTime::get_day_of_month | ( |  | ) | const

Retrieves the day of the month represented by datetime in the gregorian calendar.

Since glibmm 2.26:

Returns
  The day of the month.

## ◆ get_day_of_week()

int Glib::DateTime::get_day_of_week | ( |  | ) | const

Retrieves the ISO 8601 day of the week on which datetime falls (1 is Monday, 2 is Tuesday...

7 is Sunday).

Since glibmm 2.26:

Returns
  The day of the week.

## ◆ get_day_of_year()

int Glib::DateTime::get_day_of_year | ( |  | ) | const

Retrieves the day of the year represented by datetime in the Gregorian calendar.

Since glibmm 2.26:

Returns
  The day of the year.

## ◆ get_hour()

int Glib::DateTime::get_hour | ( |  | ) | const

Retrieves the hour of the day represented by datetime.

Since glibmm 2.26:

Returns
  The hour of the day.

## ◆ get_microsecond()

int Glib::DateTime::get_microsecond | ( |  | ) | const

Retrieves the microsecond of the date represented by datetime.

Since glibmm 2.26:

Returns
  The microsecond of the second.

## ◆ get_minute()

int Glib::DateTime::get_minute | ( |  | ) | const

Retrieves the minute of the hour represented by datetime.

Since glibmm 2.26:

Returns
  The minute of the hour.

## ◆ get_month()

int Glib::DateTime::get_month | ( |  | ) | const

Retrieves the month of the year represented by datetime in the Gregorian calendar.

Since glibmm 2.26:

Returns
  The month represented by datetime.

## ◆ get_second()

int Glib::DateTime::get_second | ( |  | ) | const

Retrieves the second of the minute represented by datetime.

Since glibmm 2.26:

Returns
  The second represented by datetime.

## ◆ get_seconds()

double Glib::DateTime::get_seconds | ( |  | ) | const

Retrieves the number of seconds since the start of the last minute, including the fractional part.

Since glibmm 2.26:

Returns
  The number of seconds.

## ◆ get_timezone()

TimeZone Glib::DateTime::get_timezone | ( |  | ) | const

Get the time zone for this datetime.

Since glibmm 2.60:

Returns
  The time zone.

## ◆ get_timezone_abbreviation()

Glib::ustring Glib::DateTime::get_timezone_abbreviation | ( |  | ) | const

Determines the time zone abbreviation to be used at the time and in the time zone of datetime.

For example, in Toronto this is currently "EST" during the winter months and "EDT" during the summer months when daylight savings time is in effect.

Since glibmm 2.26:

Returns
  The time zone abbreviation. The returned string is owned by the DateTime and it should not be modified or freed.

## ◆ get_utc_offset()

TimeSpan Glib::DateTime::get_utc_offset | ( |  | ) | const

Determines the offset to UTC in effect at the time and in the time zone of datetime.

The offset is the number of microseconds that you add to UTC time to arrive at local time for the time zone (ie: negative numbers for time zones west of GMT, positive numbers for east).

If datetime represents UTC time, then the offset is always zero.

Since glibmm 2.26:

Returns
  The number of microseconds that should be added to UTC to get the local time.

## ◆ get_week_numbering_year()

int Glib::DateTime::get_week_numbering_year | ( |  | ) | const

Returns the ISO 8601 week-numbering year in which the week containing datetime falls.

This function, taken together with g_date_time_get_week_of_year() and g_date_time_get_day_of_week() can be used to determine the full ISO week date on which datetime falls.

This is usually equal to the normal Gregorian year (as returned by g_date_time_get_year()), except as detailed below:

For Thursday, the week-numbering year is always equal to the usual calendar year. For other days, the number is such that every day within a complete week (Monday to Sunday) is contained within the same week-numbering year.

For Monday, Tuesday and Wednesday occurring near the end of the year, this may mean that the week-numbering year is one greater than the calendar year (so that these days have the same week-numbering year as the Thursday occurring early in the next year).

For Friday, Saturday and Sunday occurring near the start of the year, this may mean that the week-numbering year is one less than the calendar year (so that these days have the same week-numbering year as the Thursday occurring late in the previous year).

An equivalent description is that the week-numbering year is equal to the calendar year containing the majority of the days in the current week (Monday to Sunday).

Note that January 1 0001 in the proleptic Gregorian calendar is a Monday, so this function never returns 0.

Since glibmm 2.26:

Returns
  The ISO 8601 week-numbering year for datetime.

## ◆ get_week_of_year()

int Glib::DateTime::get_week_of_year | ( |  | ) | const

Returns the ISO 8601 week number for the week containing datetime.

The ISO 8601 week number is the same for every day of the week (from Moday through Sunday). That can produce some unusual results (described below).

The first week of the year is week 1. This is the week that contains the first Thursday of the year. Equivalently, this is the first week that has more than 4 of its days falling within the calendar year.

The value 0 is never returned by this function. Days contained within a year but occurring before the first ISO 8601 week of that year are considered as being contained in the last week of the previous year. Similarly, the final days of a calendar year may be considered as being part of the first ISO 8601 week of the next year if 4 or more days of that week are contained within the new year.

Since glibmm 2.26:

Returns
  The ISO 8601 week number for datetime.

## ◆ get_year()

int Glib::DateTime::get_year | ( |  | ) | const

Retrieves the year represented by datetime in the Gregorian calendar.

Since glibmm 2.26:

Returns
  The year represented by datetime.

## ◆ get_ymd()

void Glib::DateTime::get_ymd | ( | int & | year,
|  | int & | month,
|  | int & | day
| ) |  | const

Retrieves the Gregorian day, month, and year of a given DateTime.

Since glibmm 2.26:

Parameters

  year | The return location for the gregorian year, or `nullptr`.
  month | The return location for the month of the year, or `nullptr`.
  day | The return location for the day of the month, or `nullptr`.

## ◆ gobj() [1/2]

GDateTime* Glib::DateTime::gobj | ( |  | ) |
| inline

## ◆ gobj() [2/2]

const GDateTime* Glib::DateTime::gobj | ( |  | ) | const
| inline

## ◆ gobj_copy()

GDateTime* Glib::DateTime::gobj_copy | ( |  | ) | const

Provides access to the underlying C instance. The caller is responsible for freeing it. Use when directly setting fields in structs.

## ◆ hash()

guint Glib::DateTime::hash | ( |  | ) | const

Hashes datetime into a `unsigned int`, suitable for use within HashTable.

Since glibmm 2.26:

Returns
  A `unsigned int` containing the hash.

## ◆ is_daylight_savings()

bool Glib::DateTime::is_daylight_savings | ( |  | ) | const

Determines if daylight savings time is in effect at the time and in the time zone of datetime.

Since glibmm 2.26:

Returns
  `true` if daylight savings time is in effect.

## ◆ operator bool()

Glib::DateTime::operator bool | ( |  | ) | const
| explicit

Returns true if the DateTime object is valid.

This will return false, for instance, if the text in create_from_iso8601() is not a valid ISO 8601 formatted string.

Since glibmm 2.62:

## ◆ operator=() [1/2]

DateTime& Glib::DateTime::operator= | ( | const DateTime & | src | ) |

## ◆ operator=() [2/2]

DateTime& Glib::DateTime::operator= | ( | DateTime && | other | ) |
| noexcept

## ◆ swap()

void Glib::DateTime::swap | ( | DateTime & | other | ) |
| noexcept

## ◆ to_local()

DateTime Glib::DateTime::to_local | ( |  | ) | const

Creates a new DateTime corresponding to the same instant in time as datetime, but in the local time zone.

This call is equivalent to calling g_date_time_to_timezone() with the time zone returned by g_time_zone_new_local().

Since glibmm 2.26:

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ to_timeval()

bool Glib::DateTime::to_timeval | ( | TimeVal & | tv | ) | const

Stores the instant in time that datetime represents into tv.

The time contained in a TimeVal is always stored in the form of seconds elapsed since 1970-01-01 00:00:00 UTC, regardless of the time zone associated with datetime.

On systems where 'long' is 32bit (ie: all 32bit systems and all Windows systems), a TimeVal is incapable of storing the entire range of values that DateTime is capable of expressing. On those systems, this function returns `false` to indicate that the time is out of range.

On systems where 'long' is 64bit, this function never fails.

Since glibmm 2.26:
  Deprecated: 2.62: TimeVal is not year-2038-safe. Use g_date_time_to_unix() instead.

Deprecated:
  Use to_unix() instead.

Parameters

  tv | A TimeVal to modify.

Returns
  `true` if successful, else `false`.

## ◆ to_timezone()

DateTime Glib::DateTime::to_timezone | ( | const TimeZone & | tz | ) | const

Create a new DateTime corresponding to the same instant in time as datetime, but in the time zone tz.

This call can fail in the case that the time goes out of bounds. For example, converting 0001-01-01 00:00:00 UTC to a time zone west of Greenwich will fail (due to the year 0 being out of range).

Since glibmm 2.26:

Parameters

  tz | The new TimeZone.

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## ◆ to_unix()

gint64 Glib::DateTime::to_unix | ( |  | ) | const

Gives the Unix time corresponding to datetime, rounding down to the nearest second.

Unix time is the number of seconds that have elapsed since 1970-01-01 00:00:00 UTC, regardless of the time zone associated with datetime.

Since glibmm 2.26:

Returns
  The Unix time corresponding to datetime.

## ◆ to_utc()

DateTime Glib::DateTime::to_utc | ( |  | ) | const

Creates a new DateTime corresponding to the same instant in time as datetime, but in UTC.

This call is equivalent to calling g_date_time_to_timezone() with the time zone returned by g_time_zone_new_utc().

Since glibmm 2.26:

Returns
  The newly created DateTime which should be freed with g_date_time_unref(), or `nullptr`.

## Friends And Related Function Documentation

## ◆ swap()

void swap | ( | DateTime & | lhs,
|  | DateTime & | rhs
| ) |  |
| related

Parameters

  lhs | The left-hand side
  rhs | The right-hand side

## ◆ wrap()

Glib::DateTime wrap | ( | GDateTime * | object,
|  | bool | take_copy = `false`
| ) |  |
| related

A Glib::wrap() method for this object.

Parameters

  object | The C instance.
  take_copy | False if the result should take ownership of the C instance. True if it should take a new copy or ref.

Returns
  A C++ instance that wraps this C instance.

## Member Data Documentation

## ◆ gobject_

GDateTime* Glib::DateTime::gobject_
| protected