## Calendar time utilities

Calendar time utilities

## Functions

gint | time_days_in_month ()
gint | time_day_of_year ()
gint | time_day_of_week ()
gboolean | time_is_leap_year ()
gint | time_leap_years_up_to ()
gchar * | isodate_from_time_t ()
time_t | time_from_isodate ()
time_t | time_add_day ()
time_t | time_add_week ()
time_t | time_day_begin ()
time_t | time_day_end ()
time_t | time_add_day_with_zone ()
time_t | time_add_week_with_zone ()
time_t | time_add_month_with_zone ()
time_t | time_year_begin_with_zone ()
time_t | time_month_begin_with_zone ()
time_t | time_week_begin_with_zone ()
time_t | time_day_begin_with_zone ()
time_t | time_day_end_with_zone ()
void | time_to_gdate_with_zone ()
struct tm | icaltimetype_to_tm ()
struct tm | icaltimetype_to_tm_with_zone ()
struct icaltimetype | tm_to_icaltimetype ()

## Description

## Functions

### time_days_in_month ()

    gint
    time_days_in_month (gint year,
                        gint month);

Returns the number of days in the month. Year is the normal year, e.g. 2001. Month is 0 (Jan) to 11 (Dec).

#### Parameters

year | The year. |
month | The month. |

#### Returns

number of days in the given month/year.

### time_day_of_year ()

    gint
    time_day_of_year (gint day,
                      gint month,
                      gint year);

Returns the 1-based day number within the year of the specified date. Year is the normal year, e.g. 2001. Month is 0 to 11.

#### Parameters

day | The day. |
month | The month. |
year | The year. |

#### Returns

the day of the year.

### time_day_of_week ()

    gint
    time_day_of_week (gint day,
                      gint month,
                      gint year);

Returns the day of the week for the specified date, 0 (Sun) to 6 (Sat). For the days that were removed on the Gregorian reformation, it returns Thursday. Year is the normal year, e.g. 2001. Month is 0 to 11.

#### Parameters

day | The day. |
month | The month. |
year | The year. |

#### Returns

the day of the week for the given date.

### time_is_leap_year ()

    gboolean
    time_is_leap_year (gint year);

Returns whether the specified year is a leap year. Year is the normal year, e.g. 2001.

#### Parameters

year | The year. |

#### Returns

TRUE if the year is leap, FALSE if not.

### time_leap_years_up_to ()

    gint
    time_leap_years_up_to (gint year);

Returns the number of leap years since year 1 up to (but not including) the specified year. Year is the normal year, e.g. 2001.

#### Parameters

year | The year. |

#### Returns

number of leap years.

### isodate_from_time_t ()

    gchar *
    isodate_from_time_t (time_t t);

Creates an ISO 8601 UTC representation from a time value.

#### Parameters

t | A time value. |

#### Returns

String with the ISO 8601 representation of the UTC time.

### time_from_isodate ()

    time_t
    time_from_isodate (const gchar *str);

Converts an ISO 8601 UTC time string into a time_t value.

#### Parameters

str | Date/time value in ISO 8601 format. |

#### Returns

Time_t corresponding to the specified ISO string. Note that we only allow UTC times at present.

### time_add_day ()

    time_t
    time_add_day (time_t time,
                  gint days);

Adds a day onto the time, using local time. Note that if clocks go forward due to daylight savings time, there are some non-existent local times, so the hour may be changed to make it a valid time. This also means that it may not be wise to keep calling `time_add_day()` to step through a certain period - if the hour gets changed to make it valid time, any further calls to `time_add_day()` will also return this hour, which may not be what you want.

#### Parameters

time | A time_t value. |
days | Number of days to add. |

#### Returns

a time_t value containing `time` plus the days added.

### time_add_week ()

    time_t
    time_add_week (time_t time,
                   gint weeks);

Adds the given number of weeks to a time value.

#### Parameters

time | A time_t value. |
weeks | Number of weeks to add. |

#### Returns

a time_t value containing `time` plus the weeks added.

### time_day_begin ()

    time_t
    time_day_begin (time_t t);

Returns the start of the day, according to the local time.

#### Parameters

t | A time_t value. |

#### Returns

the time corresponding to the beginning of the day.

### time_day_end ()

    time_t
    time_day_end (time_t t);

Returns the end of the day, according to the local time.

#### Parameters

t | A time_t value. |

#### Returns

the time corresponding to the end of the day.

### time_add_day_with_zone ()

    time_t
    time_add_day_with_zone (time_t time,
                            gint days,
                            icaltimezone *zone);

Adds or subtracts a number of days to/from the given time_t value, using the given timezone. NOTE: this function is only here to make the transition to the timezone functions easier. New code should use icaltimetype values and `icaltime_adjust()` to add or subtract days, hours, minutes & seconds.

#### Parameters

time | A time_t value. |
days | Number of days to add. |
zone | Timezone to use. |

#### Returns

a time_t value containing `time` plus the days added.

### time_add_week_with_zone ()

    time_t
    time_add_week_with_zone (time_t time,
                             gint weeks,
                             icaltimezone *zone);

Adds or subtracts a number of weeks to/from the given time_t value, using the given timezone. NOTE: this function is only here to make the transition to the timezone functions easier. New code should use icaltimetype values and `icaltime_adjust()` to add or subtract days, hours, minutes & seconds.

#### Parameters

time | A time_t value. |
weeks | Number of weeks to add. |
zone | Timezone to use. |

#### Returns

a time_t value containing `time` plus the weeks added.

### time_add_month_with_zone ()

    time_t
    time_add_month_with_zone (time_t time,
                              gint months,
                              icaltimezone *zone);

Adds or subtracts a number of months to/from the given time_t value, using the given timezone.

If the day would be off the end of the month (e.g. adding 1 month to 30th January, would lead to an invalid day, 30th February), it moves it down to the last day in the month, e.g. 28th Feb (or 29th in a leap year.)

NOTE: this function is only here to make the transition to the timezone functions easier. New code should use icaltimetype values and `icaltime_adjust()` to add or subtract days, hours, minutes & seconds.

#### Parameters

time | A time_t value. |
months | Number of months to add. |
zone | Timezone to use. |

#### Returns

a time_t value containing `time` plus the months added.

### time_year_begin_with_zone ()

    time_t
    time_year_begin_with_zone (time_t time,
                               icaltimezone *zone);

Returns the start of the year containing the given time_t, using the given timezone. NOTE: this function is only here to make the transition to the timezone functions easier. New code should use icaltimetype values and `icaltime_adjust()` to add or subtract days, hours, minutes & seconds.

#### Parameters

time | A time_t value. |
zone | Timezone to use. |

#### Returns

the beginning of the year.

### time_month_begin_with_zone ()

    time_t
    time_month_begin_with_zone (time_t time,
                                icaltimezone *zone);

Returns the start of the month containing the given time_t, using the given timezone. NOTE: this function is only here to make the transition to the timezone functions easier. New code should use icaltimetype values and `icaltime_adjust()` to add or subtract days, hours, minutes & seconds.

#### Parameters

time | A time_t value. |
zone | Timezone to use. |

#### Returns

the beginning of the month.

### time_week_begin_with_zone ()

    time_t
    time_week_begin_with_zone (time_t time,
                               gint week_start_day,
                               icaltimezone *zone);

Returns the start of the week containing the given time_t, using the given timezone. week_start_day should use the same values as `mktime()`, i.e. 0 (Sun) to 6 (Sat). NOTE: this function is only here to make the transition to the timezone functions easier. New code should use icaltimetype values and `icaltime_adjust()` to add or subtract days, hours, minutes & seconds.

#### Parameters

time | A time_t value. |
week_start_day | Day to use as the starting of the week. |
zone | Timezone to use. |

#### Returns

the beginning of the week.

### time_day_begin_with_zone ()

    time_t
    time_day_begin_with_zone (time_t time,
                              icaltimezone *zone);

Returns the start of the day containing the given time_t, using the given timezone. NOTE: this function is only here to make the transition to the timezone functions easier. New code should use icaltimetype values and `icaltime_adjust()` to add or subtract days, hours, minutes & seconds.

#### Parameters

time | A time_t value. |
zone | Timezone to use. |

#### Returns

the beginning of the day.

### time_day_end_with_zone ()

    time_t
    time_day_end_with_zone (time_t time,
                            icaltimezone *zone);

Returns the end of the day containing the given time_t, using the given timezone. (The end of the day is the start of the next day.) NOTE: this function is only here to make the transition to the timezone functions easier. New code should use icaltimetype values and `icaltime_adjust()` to add or subtract days, hours, minutes & seconds.

#### Parameters

time | A time_t value. |
zone | Timezone to use. |

#### Returns

the end of the day.

### time_to_gdate_with_zone ()

    void
    time_to_gdate_with_zone (GDate *date,
                             time_t time,
                             icaltimezone *zone);

Converts a time_t value to a GDate structure using the specified timezone. This is analogous to `g_date_set_time()` but takes the timezone into account.

#### Parameters

date | Destination GDate value. |
time | A time value. |
zone | Desired timezone for destination `date` , or NULL if the UTC timezone is desired. |

### icaltimetype_to_tm ()

    struct tm
    icaltimetype_to_tm (struct icaltimetype *itt);

Convers an icaltimetype structure into a GLibc's struct tm.

#### Parameters

itt | An icaltimetype structure. |

#### Returns

The converted time as a struct tm. All fields will be set properly except for tm.tm_yday.

Since 2.22

### icaltimetype_to_tm_with_zone ()

    struct tm
    icaltimetype_to_tm_with_zone (struct icaltimetype *itt,
                                  icaltimezone *from_zone,
                                  icaltimezone *to_zone);

Converts a time value from one timezone to another, and returns a struct tm representation of the time.

#### Parameters

itt | A time value. |
from_zone | Source timezone. |
to_zone | Destination timezone. |

#### Returns

The converted time as a struct tm. All fields will be set properly except for tm.tm_yday.

Since 2.22

### tm_to_icaltimetype ()

    struct icaltimetype
    tm_to_icaltimetype (struct tm *tm,
                        gboolean is_date);

Converts a struct tm into an icaltimetype.

#### Parameters

tm | A struct tm. |
is_date | Whether the given time is a date only or not. |

#### Returns

The converted time as an icaltimetype.

Since 2.22

## Types and Values