xref: /external/icu4c/i18n/unicode/ucal.h

/*
 *******************************************************************************
 * Copyright (C) 1996-2009, International Business Machines Corporation and
 * others. All Rights Reserved.
 *******************************************************************************
 */

#ifndef UCAL_H
#define UCAL_H

#include "unicode/utypes.h"
#include "unicode/uenum.h"
#include "unicode/uloc.h"

#if !UCONFIG_NO_FORMATTING

/**
 * \file
 * \brief C API: Calendar
 *
 * <h2>Calendar C API</h2>
 *
 * UCalendar C API is used  for converting between a <code>UDate</code> object
 * and a set of integer fields such as <code>UCAL_YEAR</code>, <code>UCAL_MONTH</code>,
 * <code>UCAL_DAY</code>, <code>UCAL_HOUR</code>, and so on.
 * (A <code>UDate</code> object represents a specific instant in
 * time with millisecond precision. See UDate
 * for information about the <code>UDate</code> .)
 *
 * <p>
 * Types of <code>UCalendar</code> interpret a <code>UDate</code>
 * according to the rules of a specific calendar system. The U_STABLE
 * provides the enum UCalendarType with UCAL_TRADITIONAL and
 * UCAL_GREGORIAN.
 * <p>
 * Like other locale-sensitive C API, calendar API  provides a
 * function, <code>ucal_open()</code>, which returns a pointer to
 * <code>UCalendar</code> whose time fields have been initialized
 * with the current date and time. We need to specify the type of
 * calendar to be opened and the  timezoneId.
 * \htmlonly<blockquote>\endhtmlonly
 * <pre>
 * \code
 * UCalendar *caldef;
 * UChar *tzId;
 * UErrorCode status;
 * tzId=(UChar*)malloc(sizeof(UChar) * (strlen("PST") +1) );
 * u_uastrcpy(tzId, "PST");
 * caldef=ucal_open(tzID, u_strlen(tzID), NULL, UCAL_TRADITIONAL, &status);
 * \endcode
 * </pre>
 * \htmlonly</blockquote>\endhtmlonly
 *
 * <p>
 * A <code>UCalendar</code> object can produce all the time field values
 * needed to implement the date-time formatting for a particular language
 * and calendar style (for example, Japanese-Gregorian, Japanese-Traditional).
 *
 * <p>
 * When computing a <code>UDate</code> from time fields, two special circumstances
 * may arise: there may be insufficient information to compute the
 * <code>UDate</code> (such as only year and month but no day in the month),
 * or there may be inconsistent information (such as "Tuesday, July 15, 1996"
 * -- July 15, 1996 is actually a Monday).
 *
 * <p>
 * <strong>Insufficient information.</strong> The calendar will use default
 * information to specify the missing fields. This may vary by calendar; for
 * the Gregorian calendar, the default for a field is the same as that of the
 * start of the epoch: i.e., UCAL_YEAR = 1970, UCAL_MONTH = JANUARY, UCAL_DATE = 1, etc.
 *
 * <p>
 * <strong>Inconsistent information.</strong> If fields conflict, the calendar
 * will give preference to fields set more recently. For example, when
 * determining the day, the calendar will look for one of the following
 * combinations of fields.  The most recent combination, as determined by the
 * most recently set single field, will be used.
 *
 * \htmlonly<blockquote>\endhtmlonly
 * <pre>
 * \code
 * UCAL_MONTH + UCAL_DAY_OF_MONTH
 * UCAL_MONTH + UCAL_WEEK_OF_MONTH + UCAL_DAY_OF_WEEK
 * UCAL_MONTH + UCAL_DAY_OF_WEEK_IN_MONTH + UCAL_DAY_OF_WEEK
 * UCAL_DAY_OF_YEAR
 * UCAL_DAY_OF_WEEK + UCAL_WEEK_OF_YEAR
 * \endcode
 * </pre>
 * \htmlonly</blockquote>\endhtmlonly
 *
 * For the time of day:
 *
 * \htmlonly<blockquote>\endhtmlonly
 * <pre>
 * \code
 * UCAL_HOUR_OF_DAY
 * UCAL_AM_PM + UCAL_HOUR
 * \endcode
 * </pre>
 * \htmlonly</blockquote>\endhtmlonly
 *
 * <p>
 * <strong>Note:</strong> for some non-Gregorian calendars, different
 * fields may be necessary for complete disambiguation. For example, a full
 * specification of the historial Arabic astronomical calendar requires year,
 * month, day-of-month <em>and</em> day-of-week in some cases.
 *
 * <p>
 * <strong>Note:</strong> There are certain possible ambiguities in
 * interpretation of certain singular times, which are resolved in the
 * following ways:
 * <ol>
 *     <li> 24:00:00 "belongs" to the following day. That is,
 *          23:59 on Dec 31, 1969 &lt; 24:00 on Jan 1, 1970 &lt; 24:01:00 on Jan 1, 1970
 *
 *     <li> Although historically not precise, midnight also belongs to "am",
 *          and noon belongs to "pm", so on the same day,
 *          12:00 am (midnight) &lt; 12:01 am, and 12:00 pm (noon) &lt; 12:01 pm
 * </ol>
 *
 * <p>
 * The date or time format strings are not part of the definition of a
 * calendar, as those must be modifiable or overridable by the user at
 * runtime. Use {@link DateFormat}
 * to format dates.
 *
 * <p>
 * <code>Calendar</code> provides an API for field "rolling", where fields
 * can be incremented or decremented, but wrap around. For example, rolling the
 * month up in the date <code>December 12, <b>1996</b></code> results in
 * <code>January 12, <b>1996</b></code>.
 *
 * <p>
 * <code>Calendar</code> also provides a date arithmetic function for
 * adding the specified (signed) amount of time to a particular time field.
 * For example, subtracting 5 days from the date <code>September 12, 1996</code>
 * results in <code>September 7, 1996</code>.
 *
 * @stable ICU 2.0
 */

/** A calendar.
 *  For usage in C programs.
 * @stable ICU 2.0
 */
typedef void* UCalendar;

/** Possible types of UCalendars
 * @stable ICU 2.0
 */
enum UCalendarType {
  /**
   * Despite the name, UCAL_TRADITIONAL designates the locale's default calendar,
   * which may be the Gregorian calendar or some other calendar.
   * @stable ICU 2.0
   */
  UCAL_TRADITIONAL,
  /**
   * Unambiguously designates the Gregorian calendar for the locale.
   * @stable ICU 2.0
   */
  UCAL_GREGORIAN,
  /**
   * A better name for UCAL_TRADITIONAL.
   * @draft ICU 4.2
   */
  UCAL_DEFAULT = UCAL_TRADITIONAL
};

/** @stable ICU 2.0 */
typedef enum UCalendarType UCalendarType;

/** Possible fields in a UCalendar
 * @stable ICU 2.0
 */
enum UCalendarDateFields {
  /**
   * Field number indicating the era, e.g., AD or BC in the Gregorian (Julian) calendar.
   * This is a calendar-specific value.
   * @stable ICU 2.6
   */
  UCAL_ERA,

  /**
   * Field number indicating the year. This is a calendar-specific value.
   * @stable ICU 2.6
   */
  UCAL_YEAR,

  /**
   * Field number indicating the month. This is a calendar-specific value.
   * The first month of the year is
   * <code>JANUARY</code>; the last depends on the number of months in a year.
   * @see #UCAL_JANUARY
   * @see #UCAL_FEBRUARY
   * @see #UCAL_MARCH
   * @see #UCAL_APRIL
   * @see #UCAL_MAY
   * @see #UCAL_JUNE
   * @see #UCAL_JULY
   * @see #UCAL_AUGUST
   * @see #UCAL_SEPTEMBER
   * @see #UCAL_OCTOBER
   * @see #UCAL_NOVEMBER
   * @see #UCAL_DECEMBER
   * @see #UCAL_UNDECIMBER
   * @stable ICU 2.6
   */
  UCAL_MONTH,

  /**
   * Field number indicating the
   * week number within the current year.  The first week of the year, as
   * defined by <code>UCAL_FIRST_DAY_OF_WEEK</code> and <code>UCAL_MINIMAL_DAYS_IN_FIRST_WEEK</code>
   * attributes, has value 1.  Subclasses define
   * the value of <code>UCAL_WEEK_OF_YEAR</code> for days before the first week of
   * the year.
   * @see ucal_getAttribute
   * @see ucal_setAttribute
   * @stable ICU 2.6
   */
  UCAL_WEEK_OF_YEAR,

 /**
   * Field number indicating the
   * week number within the current month.  The first week of the month, as
   * defined by <code>UCAL_FIRST_DAY_OF_WEEK</code> and <code>UCAL_MINIMAL_DAYS_IN_FIRST_WEEK</code>
   * attributes, has value 1.  Subclasses define
   * the value of <code>WEEK_OF_MONTH</code> for days before the first week of
   * the month.
   * @see ucal_getAttribute
   * @see ucal_setAttribute
   * @see #UCAL_FIRST_DAY_OF_WEEK
   * @see #UCAL_MINIMAL_DAYS_IN_FIRST_WEEK
   * @stable ICU 2.6
   */
  UCAL_WEEK_OF_MONTH,

 /**
   * Field number indicating the
   * day of the month. This is a synonym for <code>DAY_OF_MONTH</code>.
   * The first day of the month has value 1.
   * @see #UCAL_DAY_OF_MONTH
   * @stable ICU 2.6
   */
  UCAL_DATE,

 /**
   * Field number indicating the day
   * number within the current year.  The first day of the year has value 1.
   * @stable ICU 2.6
   */
  UCAL_DAY_OF_YEAR,

 /**
   * Field number indicating the day
   * of the week.  This field takes values <code>SUNDAY</code>,
   * <code>MONDAY</code>, <code>TUESDAY</code>, <code>WEDNESDAY</code>,
   * <code>THURSDAY</code>, <code>FRIDAY</code>, and <code>SATURDAY</code>.
   * @see #UCAL_SUNDAY
   * @see #UCAL_MONDAY
   * @see #UCAL_TUESDAY
   * @see #UCAL_WEDNESDAY
   * @see #UCAL_THURSDAY
   * @see #UCAL_FRIDAY
   * @see #UCAL_SATURDAY
   * @stable ICU 2.6
   */
  UCAL_DAY_OF_WEEK,

 /**
   * Field number indicating the
   * ordinal number of the day of the week within the current month. Together
   * with the <code>DAY_OF_WEEK</code> field, this uniquely specifies a day
   * within a month.  Unlike <code>WEEK_OF_MONTH</code> and
   * <code>WEEK_OF_YEAR</code>, this field's value does <em>not</em> depend on
   * <code>getFirstDayOfWeek()</code> or
   * <code>getMinimalDaysInFirstWeek()</code>.  <code>DAY_OF_MONTH 1</code>
   * through <code>7</code> always correspond to <code>DAY_OF_WEEK_IN_MONTH
   * 1</code>; <code>8</code> through <code>15</code> correspond to
   * <code>DAY_OF_WEEK_IN_MONTH 2</code>, and so on.
   * <code>DAY_OF_WEEK_IN_MONTH 0</code> indicates the week before
   * <code>DAY_OF_WEEK_IN_MONTH 1</code>.  Negative values count back from the
   * end of the month, so the last Sunday of a month is specified as
   * <code>DAY_OF_WEEK = SUNDAY, DAY_OF_WEEK_IN_MONTH = -1</code>.  Because
   * negative values count backward they will usually be aligned differently
   * within the month than positive values.  For example, if a month has 31
   * days, <code>DAY_OF_WEEK_IN_MONTH -1</code> will overlap
   * <code>DAY_OF_WEEK_IN_MONTH 5</code> and the end of <code>4</code>.
   * @see #UCAL_DAY_OF_WEEK
   * @see #UCAL_WEEK_OF_MONTH
   * @stable ICU 2.6
   */
  UCAL_DAY_OF_WEEK_IN_MONTH,

 /**
   * Field number indicating
   * whether the <code>HOUR</code> is before or after noon.
   * E.g., at 10:04:15.250 PM the <code>AM_PM</code> is <code>PM</code>.
   * @see #UCAL_AM
   * @see #UCAL_PM
   * @see #UCAL_HOUR
   * @stable ICU 2.6
   */
  UCAL_AM_PM,

 /**
   * Field number indicating the
   * hour of the morning or afternoon. <code>HOUR</code> is used for the 12-hour
   * clock.
   * E.g., at 10:04:15.250 PM the <code>HOUR</code> is 10.
   * @see #UCAL_AM_PM
   * @see #UCAL_HOUR_OF_DAY
   * @stable ICU 2.6
   */
  UCAL_HOUR,

 /**
   * Field number indicating the
   * hour of the day. <code>HOUR_OF_DAY</code> is used for the 24-hour clock.
   * E.g., at 10:04:15.250 PM the <code>HOUR_OF_DAY</code> is 22.
   * @see #UCAL_HOUR
   * @stable ICU 2.6
   */
  UCAL_HOUR_OF_DAY,

 /**
   * Field number indicating the
   * minute within the hour.
   * E.g., at 10:04:15.250 PM the <code>UCAL_MINUTE</code> is 4.
   * @stable ICU 2.6
   */
  UCAL_MINUTE,

 /**
   * Field number indicating the
   * second within the minute.
   * E.g., at 10:04:15.250 PM the <code>UCAL_SECOND</code> is 15.
   * @stable ICU 2.6
   */
  UCAL_SECOND,

 /**
   * Field number indicating the
   * millisecond within the second.
   * E.g., at 10:04:15.250 PM the <code>UCAL_MILLISECOND</code> is 250.
   * @stable ICU 2.6
   */
  UCAL_MILLISECOND,

 /**
   * Field number indicating the
   * raw offset from GMT in milliseconds.
   * @stable ICU 2.6
   */
  UCAL_ZONE_OFFSET,

 /**
   * Field number indicating the
   * daylight savings offset in milliseconds.
   * @stable ICU 2.6
   */
  UCAL_DST_OFFSET,

 /**
   * Field number
   * indicating the extended year corresponding to the
   * <code>UCAL_WEEK_OF_YEAR</code> field.  This may be one greater or less
   * than the value of <code>UCAL_EXTENDED_YEAR</code>.
   * @stable ICU 2.6
   */
  UCAL_YEAR_WOY,

 /**
   * Field number
   * indicating the localized day of week.  This will be a value from 1
   * to 7 inclusive, with 1 being the localized first day of the week.
   * @stable ICU 2.6
   */
  UCAL_DOW_LOCAL,

  /**
   * Year of this calendar system, encompassing all supra-year fields. For example,
   * in Gregorian/Julian calendars, positive Extended Year values indicate years AD,
   *  1 BC = 0 extended, 2 BC = -1 extended, and so on.
   * @stable ICU 2.8
   */
  UCAL_EXTENDED_YEAR,

 /**
   * Field number
   * indicating the modified Julian day number.  This is different from
   * the conventional Julian day number in two regards.  First, it
   * demarcates days at local zone midnight, rather than noon GMT.
   * Second, it is a local number; that is, it depends on the local time
   * zone.  It can be thought of as a single number that encompasses all
   * the date-related fields.
   * @stable ICU 2.8
   */
  UCAL_JULIAN_DAY,

  /**
   * Ranges from 0 to 23:59:59.999 (regardless of DST).  This field behaves <em>exactly</em>
   * like a composite of all time-related fields, not including the zone fields.  As such,
   * it also reflects discontinuities of those fields on DST transition days.  On a day
   * of DST onset, it will jump forward.  On a day of DST cessation, it will jump
   * backward.  This reflects the fact that it must be combined with the DST_OFFSET field
   * to obtain a unique local time value.
   * @stable ICU 2.8
   */
  UCAL_MILLISECONDS_IN_DAY,

  /**
   * Whether or not the current month is a leap month (0 or 1). See the Chinese calendar for
   * an example of this.
   */
  UCAL_IS_LEAP_MONTH,

  /**
   * Field count
   * @stable ICU 2.6
   */
  UCAL_FIELD_COUNT,

 /**
   * Field number indicating the
   * day of the month. This is a synonym for <code>UCAL_DATE</code>.
   * The first day of the month has value 1.
   * @see #UCAL_DATE
   * Synonym for UCAL_DATE
   * @stable ICU 2.8
   **/
  UCAL_DAY_OF_MONTH=UCAL_DATE
};

/** @stable ICU 2.0 */
typedef enum UCalendarDateFields UCalendarDateFields;
    /**
     * Useful constant for days of week. Note: Calendar day-of-week is 1-based. Clients
     * who create locale resources for the field of first-day-of-week should be aware of
     * this. For instance, in US locale, first-day-of-week is set to 1, i.e., UCAL_SUNDAY.
     */
/** Possible days of the week in a UCalendar
 * @stable ICU 2.0
 */
enum UCalendarDaysOfWeek {
  /** Sunday */
  UCAL_SUNDAY = 1,
  /** Monday */
  UCAL_MONDAY,
  /** Tuesday */
  UCAL_TUESDAY,
  /** Wednesday */
  UCAL_WEDNESDAY,
  /** Thursday */
  UCAL_THURSDAY,
  /** Friday */
  UCAL_FRIDAY,
  /** Saturday */
  UCAL_SATURDAY
};

/** @stable ICU 2.0 */
typedef enum UCalendarDaysOfWeek UCalendarDaysOfWeek;

/** Possible months in a UCalendar. Note: Calendar month is 0-based.
 * @stable ICU 2.0
 */
enum UCalendarMonths {
  /** January */
  UCAL_JANUARY,
  /** February */
  UCAL_FEBRUARY,
  /** March */
  UCAL_MARCH,
  /** April */
  UCAL_APRIL,
  /** May */
  UCAL_MAY,
  /** June */
  UCAL_JUNE,
  /** July */
  UCAL_JULY,
  /** August */
  UCAL_AUGUST,
  /** September */
  UCAL_SEPTEMBER,
  /** October */
  UCAL_OCTOBER,
  /** November */
  UCAL_NOVEMBER,
  /** December */
  UCAL_DECEMBER,
  /** Value of the <code>UCAL_MONTH</code> field indicating the
    * thirteenth month of the year. Although the Gregorian calendar
    * does not use this value, lunar calendars do.
    */
  UCAL_UNDECIMBER
};

/** @stable ICU 2.0 */
typedef enum UCalendarMonths UCalendarMonths;

/** Possible AM/PM values in a UCalendar
 * @stable ICU 2.0
 */
enum UCalendarAMPMs {
    /** AM */
  UCAL_AM,
  /** PM */
  UCAL_PM
};

/** @stable ICU 2.0 */
typedef enum UCalendarAMPMs UCalendarAMPMs;

/**
 * Create an enumeration over all time zones.
 *
 * @param ec input/output error code
 *
 * @return an enumeration object that the caller must dispose of using
 * uenum_close(), or NULL upon failure. In case of failure *ec will
 * indicate the error.
 *
 * @stable ICU 2.6
 */
U_STABLE UEnumeration* U_EXPORT2
ucal_openTimeZones(UErrorCode* ec);

/**
 * Create an enumeration over all time zones associated with the given
 * country. Some zones are affiliated with no country (e.g., "UTC");
 * these may also be retrieved, as a group.
 *
 * @param country the ISO 3166 two-letter country code, or NULL to
 * retrieve zones not affiliated with any country
 *
 * @param ec input/output error code
 *
 * @return an enumeration object that the caller must dispose of using
 * uenum_close(), or NULL upon failure. In case of failure *ec will
 * indicate the error.
 *
 * @stable ICU 2.6
 */
U_STABLE UEnumeration* U_EXPORT2
ucal_openCountryTimeZones(const char* country, UErrorCode* ec);

/**
 * Return the default time zone. The default is determined initially
 * by querying the host operating system. It may be changed with
 * ucal_setDefaultTimeZone() or with the C++ TimeZone API.
 *
 * @param result A buffer to receive the result, or NULL
 *
 * @param resultCapacity The capacity of the result buffer
 *
 * @param ec input/output error code
 *
 * @return The result string length, not including the terminating
 * null
 *
 * @stable ICU 2.6
 */
U_STABLE int32_t U_EXPORT2
ucal_getDefaultTimeZone(UChar* result, int32_t resultCapacity, UErrorCode* ec);

/**
 * Set the default time zone.
 *
 * @param zoneID null-terminated time zone ID
 *
 * @param ec input/output error code
 *
 * @stable ICU 2.6
 */
U_STABLE void U_EXPORT2
ucal_setDefaultTimeZone(const UChar* zoneID, UErrorCode* ec);

/**
 * Return the amount of time in milliseconds that the clock is
 * advanced during daylight savings time for the given time zone, or
 * zero if the time zone does not observe daylight savings time.
 *
 * @param zoneID null-terminated time zone ID
 *
 * @param ec input/output error code
 *
 * @return the number of milliseconds the time is advanced with
 * respect to standard time when the daylight savings rules are in
 * effect. This is always a non-negative number, most commonly either
 * 3,600,000 (one hour) or zero.
 *
 * @stable ICU 2.6
 */
U_STABLE int32_t U_EXPORT2
ucal_getDSTSavings(const UChar* zoneID, UErrorCode* ec);

/**
 * Get the current date and time.
 * The value returned is represented as milliseconds from the epoch.
 * @return The current date and time.
 * @stable ICU 2.0
 */
U_STABLE UDate U_EXPORT2
ucal_getNow(void);

/**
 * Open a UCalendar.
 * A UCalendar may be used to convert a millisecond value to a year,
 * month, and day.
 * <p>
 * Note: When unknown TimeZone ID is specified, the UCalendar returned
 * by the function is initialized with GMT ("Etc/GMT") without any
 * errors/warnings.  If you want to check if a TimeZone ID is valid,
 * use ucal_getCanonicalTimeZoneID prior to this function.
 *
 * @param zoneID The desired TimeZone ID.  If 0, use the default time zone.
 * @param len The length of zoneID, or -1 if null-terminated.
 * @param locale The desired locale
 * @param type The type of UCalendar to open. This can be UCAL_GREGORIAN to open the Gregorian
 * calendar for the locale, or UCAL_DEFAULT to open the default calendar for the locale (the
 * default calendar may also be Gregorian). To open a specific non-Gregorian calendar for the
 * locale, use uloc_setKeywordValue to set the value of the calendar keyword for the locale
 * and then pass the locale to ucal_open with UCAL_DEFAULT as the type.
 * @param status A pointer to an UErrorCode to receive any errors
 * @return A pointer to a UCalendar, or 0 if an error occurred.
 * @stable ICU 2.0
 */
U_STABLE UCalendar* U_EXPORT2
ucal_open(const UChar*   zoneID,
          int32_t        len,
          const char*    locale,
          UCalendarType  type,
          UErrorCode*    status);

/**
 * Close a UCalendar.
 * Once closed, a UCalendar may no longer be used.
 * @param cal The UCalendar to close.
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_close(UCalendar *cal);

/**
 * Open a copy of a UCalendar.
 * This function performs a deep copy.
 * @param cal The calendar to copy
 * @param status A pointer to an UErrorCode to receive any errors.
 * @return A pointer to a UCalendar identical to cal.
 * @stable ICU 4.0
 */
U_DRAFT UCalendar* U_EXPORT2
ucal_clone(const UCalendar* cal,
           UErrorCode*      status);

/**
 * Set the TimeZone used by a UCalendar.
 * A UCalendar uses a timezone for converting from Greenwich time to local time.
 * @param cal The UCalendar to set.
 * @param zoneID The desired TimeZone ID.  If 0, use the default time zone.
 * @param len The length of zoneID, or -1 if null-terminated.
 * @param status A pointer to an UErrorCode to receive any errors.
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_setTimeZone(UCalendar*    cal,
                 const UChar*  zoneID,
                 int32_t       len,
                 UErrorCode*   status);

/**
 * Possible formats for a UCalendar's display name
 * @stable ICU 2.0
 */
enum UCalendarDisplayNameType {
  /** Standard display name */
  UCAL_STANDARD,
  /** Short standard display name */
  UCAL_SHORT_STANDARD,
  /** Daylight savings display name */
  UCAL_DST,
  /** Short daylight savings display name */
  UCAL_SHORT_DST
};

/** @stable ICU 2.0 */
typedef enum UCalendarDisplayNameType UCalendarDisplayNameType;

/**
 * Get the display name for a UCalendar's TimeZone.
 * A display name is suitable for presentation to a user.
 * @param cal          The UCalendar to query.
 * @param type         The desired display name format; one of UCAL_STANDARD, UCAL_SHORT_STANDARD,
 *                     UCAL_DST, UCAL_SHORT_DST
 * @param locale       The desired locale for the display name.
 * @param result       A pointer to a buffer to receive the formatted number.
 * @param resultLength The maximum size of result.
 * @param status       A pointer to an UErrorCode to receive any errors
 * @return             The total buffer size needed; if greater than resultLength, the output was truncated.
 * @stable ICU 2.0
 */
U_STABLE int32_t U_EXPORT2
ucal_getTimeZoneDisplayName(const UCalendar*          cal,
                            UCalendarDisplayNameType  type,
                            const char*               locale,
                            UChar*                    result,
                            int32_t                   resultLength,
                            UErrorCode*               status);

/**
 * Determine if a UCalendar is currently in daylight savings time.
 * Daylight savings time is not used in all parts of the world.
 * @param cal The UCalendar to query.
 * @param status A pointer to an UErrorCode to receive any errors
 * @return TRUE if cal is currently in daylight savings time, FALSE otherwise
 * @stable ICU 2.0
 */
U_STABLE UBool U_EXPORT2
ucal_inDaylightTime(const UCalendar*  cal,
                    UErrorCode*       status );

/**
 * Sets the GregorianCalendar change date. This is the point when the switch from
 * Julian dates to Gregorian dates occurred. Default is 00:00:00 local time, October
 * 15, 1582. Previous to this time and date will be Julian dates.
 *
 * This function works only for Gregorian calendars. If the UCalendar is not
 * an instance of a Gregorian calendar, then a U_UNSUPPORTED_ERROR
 * error code is set.
 *
 * @param cal        The calendar object.
 * @param date       The given Gregorian cutover date.
 * @param pErrorCode Pointer to a standard ICU error code. Its input value must
 *                   pass the U_SUCCESS() test, or else the function returns
 *                   immediately. Check for U_FAILURE() on output or use with
 *                   function chaining. (See User Guide for details.)
 *
 * @see GregorianCalendar::setGregorianChange
 * @see ucal_getGregorianChange
 * @stable ICU 3.6
 */
U_STABLE void U_EXPORT2
ucal_setGregorianChange(UCalendar *cal, UDate date, UErrorCode *pErrorCode);

/**
 * Gets the Gregorian Calendar change date. This is the point when the switch from
 * Julian dates to Gregorian dates occurred. Default is 00:00:00 local time, October
 * 15, 1582. Previous to this time and date will be Julian dates.
 *
 * This function works only for Gregorian calendars. If the UCalendar is not
 * an instance of a Gregorian calendar, then a U_UNSUPPORTED_ERROR
 * error code is set.
 *
 * @param cal        The calendar object.
 * @param pErrorCode Pointer to a standard ICU error code. Its input value must
 *                   pass the U_SUCCESS() test, or else the function returns
 *                   immediately. Check for U_FAILURE() on output or use with
 *                   function chaining. (See User Guide for details.)
 * @return   The Gregorian cutover time for this calendar.
 *
 * @see GregorianCalendar::getGregorianChange
 * @see ucal_setGregorianChange
 * @stable ICU 3.6
 */
U_STABLE UDate U_EXPORT2
ucal_getGregorianChange(const UCalendar *cal, UErrorCode *pErrorCode);

/**
 * Types of UCalendar attributes
 * @stable ICU 2.0
 */
enum UCalendarAttribute {
    /** Lenient parsing */
  UCAL_LENIENT,
  /** First day of week */
  UCAL_FIRST_DAY_OF_WEEK,
  /** Minimum number of days in first week */
  UCAL_MINIMAL_DAYS_IN_FIRST_WEEK
};

/** @stable ICU 2.0 */
typedef enum UCalendarAttribute UCalendarAttribute;

/**
 * Get a numeric attribute associated with a UCalendar.
 * Numeric attributes include the first day of the week, or the minimal numbers
 * of days in the first week of the month.
 * @param cal The UCalendar to query.
 * @param attr The desired attribute; one of UCAL_LENIENT, UCAL_FIRST_DAY_OF_WEEK,
 * or UCAL_MINIMAL_DAYS_IN_FIRST_WEEK
 * @return The value of attr.
 * @see ucal_setAttribute
 * @stable ICU 2.0
 */
U_STABLE int32_t U_EXPORT2
ucal_getAttribute(const UCalendar*    cal,
                  UCalendarAttribute  attr);

/**
 * Set a numeric attribute associated with a UCalendar.
 * Numeric attributes include the first day of the week, or the minimal numbers
 * of days in the first week of the month.
 * @param cal The UCalendar to set.
 * @param attr The desired attribute; one of UCAL_LENIENT, UCAL_FIRST_DAY_OF_WEEK,
 * or UCAL_MINIMAL_DAYS_IN_FIRST_WEEK
 * @param newValue The new value of attr.
 * @see ucal_getAttribute
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_setAttribute(UCalendar*          cal,
                  UCalendarAttribute  attr,
                  int32_t             newValue);

/**
 * Get a locale for which calendars are available.
 * A UCalendar in a locale returned by this function will contain the correct
 * day and month names for the locale.
 * @param localeIndex The index of the desired locale.
 * @return A locale for which calendars are available, or 0 if none.
 * @see ucal_countAvailable
 * @stable ICU 2.0
 */
U_STABLE const char* U_EXPORT2
ucal_getAvailable(int32_t localeIndex);

/**
 * Determine how many locales have calendars available.
 * This function is most useful as determining the loop ending condition for
 * calls to \ref ucal_getAvailable.
 * @return The number of locales for which calendars are available.
 * @see ucal_getAvailable
 * @stable ICU 2.0
 */
U_STABLE int32_t U_EXPORT2
ucal_countAvailable(void);

/**
 * Get a UCalendar's current time in millis.
 * The time is represented as milliseconds from the epoch.
 * @param cal The UCalendar to query.
 * @param status A pointer to an UErrorCode to receive any errors
 * @return The calendar's current time in millis.
 * @see ucal_setMillis
 * @see ucal_setDate
 * @see ucal_setDateTime
 * @stable ICU 2.0
 */
U_STABLE UDate U_EXPORT2
ucal_getMillis(const UCalendar*  cal,
               UErrorCode*       status);

/**
 * Set a UCalendar's current time in millis.
 * The time is represented as milliseconds from the epoch.
 * @param cal The UCalendar to set.
 * @param dateTime The desired date and time.
 * @param status A pointer to an UErrorCode to receive any errors
 * @see ucal_getMillis
 * @see ucal_setDate
 * @see ucal_setDateTime
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_setMillis(UCalendar*   cal,
               UDate        dateTime,
               UErrorCode*  status );

/**
 * Set a UCalendar's current date.
 * The date is represented as a series of 32-bit integers.
 * @param cal The UCalendar to set.
 * @param year The desired year.
 * @param month The desired month; one of UCAL_JANUARY, UCAL_FEBRUARY, UCAL_MARCH, UCAL_APRIL, UCAL_MAY,
 * UCAL_JUNE, UCAL_JULY, UCAL_AUGUST, UCAL_SEPTEMBER, UCAL_OCTOBER, UCAL_NOVEMBER, UCAL_DECEMBER, UCAL_UNDECIMBER
 * @param date The desired day of the month.
 * @param status A pointer to an UErrorCode to receive any errors
 * @see ucal_getMillis
 * @see ucal_setMillis
 * @see ucal_setDateTime
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_setDate(UCalendar*   cal,
             int32_t      year,
             int32_t      month,
             int32_t      date,
             UErrorCode*  status);

/**
 * Set a UCalendar's current date.
 * The date is represented as a series of 32-bit integers.
 * @param cal The UCalendar to set.
 * @param year The desired year.
 * @param month The desired month; one of UCAL_JANUARY, UCAL_FEBRUARY, UCAL_MARCH, UCAL_APRIL, UCAL_MAY,
 * UCAL_JUNE, UCAL_JULY, UCAL_AUGUST, UCAL_SEPTEMBER, UCAL_OCTOBER, UCAL_NOVEMBER, UCAL_DECEMBER, UCAL_UNDECIMBER
 * @param date The desired day of the month.
 * @param hour The desired hour of day.
 * @param minute The desired minute.
 * @param second The desirec second.
 * @param status A pointer to an UErrorCode to receive any errors
 * @see ucal_getMillis
 * @see ucal_setMillis
 * @see ucal_setDate
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_setDateTime(UCalendar*   cal,
                 int32_t      year,
                 int32_t      month,
                 int32_t      date,
                 int32_t      hour,
                 int32_t      minute,
                 int32_t      second,
                 UErrorCode*  status);

/**
 * Returns TRUE if two UCalendars are equivalent.  Equivalent
 * UCalendars will behave identically, but they may be set to
 * different times.
 * @param cal1 The first of the UCalendars to compare.
 * @param cal2 The second of the UCalendars to compare.
 * @return TRUE if cal1 and cal2 are equivalent, FALSE otherwise.
 * @stable ICU 2.0
 */
U_STABLE UBool U_EXPORT2
ucal_equivalentTo(const UCalendar*  cal1,
                  const UCalendar*  cal2);

/**
 * Add a specified signed amount to a particular field in a UCalendar.
 * This can modify more significant fields in the calendar.
 * @param cal The UCalendar to which to add.
 * @param field The field to which to add the signed value; one of UCAL_ERA, UCAL_YEAR, UCAL_MONTH,
 * UCAL_WEEK_OF_YEAR, UCAL_WEEK_OF_MONTH, UCAL_DATE, UCAL_DAY_OF_YEAR, UCAL_DAY_OF_WEEK,
 * UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_AM_PM, UCAL_HOUR, UCAL_HOUR_OF_DAY, UCAL_MINUTE, UCAL_SECOND,
 * UCAL_MILLISECOND, UCAL_ZONE_OFFSET, UCAL_DST_OFFSET.
 * @param amount The signed amount to add to field. If the amount causes the value
 * to exceed to maximum or minimum values for that field, other fields are modified
 * to preserve the magnitude of the change.
 * @param status A pointer to an UErrorCode to receive any errors
 * @see ucal_roll
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_add(UCalendar*           cal,
         UCalendarDateFields  field,
         int32_t              amount,
         UErrorCode*          status);

/**
 * Add a specified signed amount to a particular field in a UCalendar.
 * This will not modify more significant fields in the calendar.
 * @param cal The UCalendar to which to add.
 * @param field The field to which to add the signed value; one of UCAL_ERA, UCAL_YEAR, UCAL_MONTH,
 * UCAL_WEEK_OF_YEAR, UCAL_WEEK_OF_MONTH, UCAL_DATE, UCAL_DAY_OF_YEAR, UCAL_DAY_OF_WEEK,
 * UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_AM_PM, UCAL_HOUR, UCAL_HOUR_OF_DAY, UCAL_MINUTE, UCAL_SECOND,
 * UCAL_MILLISECOND, UCAL_ZONE_OFFSET, UCAL_DST_OFFSET.
 * @param amount The signed amount to add to field. If the amount causes the value
 * to exceed to maximum or minimum values for that field, the field is pinned to a permissible
 * value.
 * @param status A pointer to an UErrorCode to receive any errors
 * @see ucal_add
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_roll(UCalendar*           cal,
          UCalendarDateFields  field,
          int32_t              amount,
          UErrorCode*          status);

/**
 * Get the current value of a field from a UCalendar.
 * All fields are represented as 32-bit integers.
 * @param cal The UCalendar to query.
 * @param field The desired field; one of UCAL_ERA, UCAL_YEAR, UCAL_MONTH,
 * UCAL_WEEK_OF_YEAR, UCAL_WEEK_OF_MONTH, UCAL_DATE, UCAL_DAY_OF_YEAR, UCAL_DAY_OF_WEEK,
 * UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_AM_PM, UCAL_HOUR, UCAL_HOUR_OF_DAY, UCAL_MINUTE, UCAL_SECOND,
 * UCAL_MILLISECOND, UCAL_ZONE_OFFSET, UCAL_DST_OFFSET.
 * @param status A pointer to an UErrorCode to receive any errors
 * @return The value of the desired field.
 * @see ucal_set
 * @see ucal_isSet
 * @see ucal_clearField
 * @see ucal_clear
 * @stable ICU 2.0
 */
U_STABLE int32_t U_EXPORT2
ucal_get(const UCalendar*     cal,
         UCalendarDateFields  field,
         UErrorCode*          status );

/**
 * Set the value of a field in a UCalendar.
 * All fields are represented as 32-bit integers.
 * @param cal The UCalendar to set.
 * @param field The field to set; one of UCAL_ERA, UCAL_YEAR, UCAL_MONTH,
 * UCAL_WEEK_OF_YEAR, UCAL_WEEK_OF_MONTH, UCAL_DATE, UCAL_DAY_OF_YEAR, UCAL_DAY_OF_WEEK,
 * UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_AM_PM, UCAL_HOUR, UCAL_HOUR_OF_DAY, UCAL_MINUTE, UCAL_SECOND,
 * UCAL_MILLISECOND, UCAL_ZONE_OFFSET, UCAL_DST_OFFSET.
 * @param value The desired value of field.
 * @see ucal_get
 * @see ucal_isSet
 * @see ucal_clearField
 * @see ucal_clear
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_set(UCalendar*           cal,
         UCalendarDateFields  field,
         int32_t              value);

/**
 * Determine if a field in a UCalendar is set.
 * All fields are represented as 32-bit integers.
 * @param cal The UCalendar to query.
 * @param field The desired field; one of UCAL_ERA, UCAL_YEAR, UCAL_MONTH,
 * UCAL_WEEK_OF_YEAR, UCAL_WEEK_OF_MONTH, UCAL_DATE, UCAL_DAY_OF_YEAR, UCAL_DAY_OF_WEEK,
 * UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_AM_PM, UCAL_HOUR, UCAL_HOUR_OF_DAY, UCAL_MINUTE, UCAL_SECOND,
 * UCAL_MILLISECOND, UCAL_ZONE_OFFSET, UCAL_DST_OFFSET.
 * @return TRUE if field is set, FALSE otherwise.
 * @see ucal_get
 * @see ucal_set
 * @see ucal_clearField
 * @see ucal_clear
 * @stable ICU 2.0
 */
U_STABLE UBool U_EXPORT2
ucal_isSet(const UCalendar*     cal,
           UCalendarDateFields  field);

/**
 * Clear a field in a UCalendar.
 * All fields are represented as 32-bit integers.
 * @param cal The UCalendar containing the field to clear.
 * @param field The field to clear; one of UCAL_ERA, UCAL_YEAR, UCAL_MONTH,
 * UCAL_WEEK_OF_YEAR, UCAL_WEEK_OF_MONTH, UCAL_DATE, UCAL_DAY_OF_YEAR, UCAL_DAY_OF_WEEK,
 * UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_AM_PM, UCAL_HOUR, UCAL_HOUR_OF_DAY, UCAL_MINUTE, UCAL_SECOND,
 * UCAL_MILLISECOND, UCAL_ZONE_OFFSET, UCAL_DST_OFFSET.
 * @see ucal_get
 * @see ucal_set
 * @see ucal_isSet
 * @see ucal_clear
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_clearField(UCalendar*           cal,
                UCalendarDateFields  field);

/**
 * Clear all fields in a UCalendar.
 * All fields are represented as 32-bit integers.
 * @param calendar The UCalendar to clear.
 * @see ucal_get
 * @see ucal_set
 * @see ucal_isSet
 * @see ucal_clearField
 * @stable ICU 2.0
 */
U_STABLE void U_EXPORT2
ucal_clear(UCalendar* calendar);

/**
 * Possible limit values for a UCalendar
 * @stable ICU 2.0
 */
enum UCalendarLimitType {
  /** Minimum value */
  UCAL_MINIMUM,
  /** Maximum value */
  UCAL_MAXIMUM,
  /** Greatest minimum value */
  UCAL_GREATEST_MINIMUM,
  /** Leaest maximum value */
  UCAL_LEAST_MAXIMUM,
  /** Actual minimum value */
  UCAL_ACTUAL_MINIMUM,
  /** Actual maximum value */
  UCAL_ACTUAL_MAXIMUM
};

/** @stable ICU 2.0 */
typedef enum UCalendarLimitType UCalendarLimitType;

/**
 * Determine a limit for a field in a UCalendar.
 * A limit is a maximum or minimum value for a field.
 * @param cal The UCalendar to query.
 * @param field The desired field; one of UCAL_ERA, UCAL_YEAR, UCAL_MONTH,
 * UCAL_WEEK_OF_YEAR, UCAL_WEEK_OF_MONTH, UCAL_DATE, UCAL_DAY_OF_YEAR, UCAL_DAY_OF_WEEK,
 * UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_AM_PM, UCAL_HOUR, UCAL_HOUR_OF_DAY, UCAL_MINUTE, UCAL_SECOND,
 * UCAL_MILLISECOND, UCAL_ZONE_OFFSET, UCAL_DST_OFFSET.
 * @param type The desired critical point; one of UCAL_MINIMUM, UCAL_MAXIMUM, UCAL_GREATEST_MINIMUM,
 * UCAL_LEAST_MAXIMUM, UCAL_ACTUAL_MINIMUM, UCAL_ACTUAL_MAXIMUM
 * @param status A pointer to an UErrorCode to receive any errors.
 * @return The requested value.
 * @stable ICU 2.0
 */
U_STABLE int32_t U_EXPORT2
ucal_getLimit(const UCalendar*     cal,
              UCalendarDateFields  field,
              UCalendarLimitType   type,
              UErrorCode*          status);

/** Get the locale for this calendar object. You can choose between valid and actual locale.
 *  @param cal The calendar object
 *  @param type type of the locale we're looking for (valid or actual)
 *  @param status error code for the operation
 *  @return the locale name
 *  @stable ICU 2.8
 */
U_STABLE const char * U_EXPORT2
ucal_getLocaleByType(const UCalendar *cal, ULocDataLocaleType type, UErrorCode* status);

/**
 * Returns the timezone data version currently used by ICU.
 * @param status error code for the operation
 * @return the version string, such as "2007f"
 * @stable ICU 3.8
 */
U_DRAFT const char * U_EXPORT2
ucal_getTZDataVersion(UErrorCode* status);

/**
 * Returns the canonical system timezone ID or the normalized
 * custom time zone ID for the given time zone ID.
 * @param id        The input timezone ID to be canonicalized.
 * @param len       The length of id, or -1 if null-terminated.
 * @param result    The buffer receives the canonical system timezone ID
 *                  or the custom timezone ID in normalized format.
 * @param resultCapacity    The capacity of the result buffer.
 * @param isSystemID        Receives if the given ID is a known system
     *                      timezone ID.
 * @param status    Recevies the status.  When the given timezone ID
 *                  is neither a known system time zone ID nor a
 *                  valid custom timezone ID, U_ILLEGAL_ARGUMENT_ERROR
 *                  is set.
 * @return          The result string length, not including the terminating
 *                  null.
 * @stable ICU 4.0
 */
U_DRAFT int32_t U_EXPORT2
ucal_getCanonicalTimeZoneID(const UChar* id, int32_t len,
                            UChar* result, int32_t resultCapacity, UBool *isSystemID, UErrorCode* status);
/**
 * Get the resource keyword value string designating the calendar type for the UCalendar.
 * @param cal The UCalendar to query.
 * @param status The error code for the operation.
 * @return The resource keyword value string.
 * @draft ICU 4.2
 */
U_DRAFT const char * U_EXPORT2
ucal_getType(const UCalendar *cal, UErrorCode* status);

/**
 * Given a key and a locale, returns an array of string values in a preferred
 * order that would make a difference. These are all and only those values where
 * the open (creation) of the service with the locale formed from the input locale
 * plus input keyword and that value has different behavior than creation with the
 * input locale alone.
 * @param key           one of the keys supported by this service.  For now, only
 *                      "calendar" is supported.
 * @param locale        the locale
 * @param commonlyUsed  if set to true it will return only commonly used values
 *                      with the given locale in preferred order.  Otherwise,
 *                      it will return all the available values for the locale.
 * @param status error status
 * @return a string enumeration over keyword values for the given key and the locale.
 * @draft ICU 4.2
 */
U_DRAFT UEnumeration* U_EXPORT2
ucal_getKeywordValuesForLocale(const char* key,
                               const char* locale,
                               UBool commonlyUsed,
                               UErrorCode* status);


#endif /* #if !UCONFIG_NO_FORMATTING */

#endif