Symbian
Symbian OS Library

SYMBIAN OS V9.3

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Calendar Conversion Overview


Purpose

Converts dates between Gregorian and Chinese calendars.

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Architectural relationships

The API uses the Date And Time Handling API. The date can be set and extracted from the calendar using the TDateTime class, which is a calendar-independent representation of the date.

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Description

The API consists of two calendar classes with a common base class and two calendar-specific date classes. The calendar classes are TGregorianCalendar which stores a Gregorian date, and TChineseCalendar which stores a Chinese date. Both calendar classes derive from the base class TCalendar, which internally stores the date as a Julian day value (a number of days since 24/11/4713 BC). The Gregorian date (year, month, day) is represented by TArithmeticalDate and the Chinese date (year cycle, year, month, leap month and day) by TChineseDate.

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Example

To convert dates both ways between the Chinese and Gregorian calendars, use TCalendar::operator=(). For example, the following code fragment converts a date stored in the Gregorian calendar into the Chinese calendar:

TArithmeticalDate date;
date.iYear=2001;
date.iMonth=1;
date.iDay=24; // 24th January 2001
TChineseCalendar chineseCalendar;
TGregorianCalendar gregorianCalendar;
gregorianCalendar.SetDate(date);
static_cast<TCalendar&>(chineseCalendar)=gregorianCalendar;
TChineseDate chineseDate;
chineseCalendar.GetDate(chineseDate); // cycle=78, Year=18, Month=1, Day=1 (New Year's day)

This is possible because both Chinese and Gregorian calendars are derived from TCalendar, which stores the date as a Julian day value. TCalendar::operator=() simply assigns the Julian day value stored in one calendar to another.

To extract the date from the calendar, use GetDate(). This gets the date as a TArithmeticalDate or a TChineseDate. The date can also be extracted as a TDateTime (note that with TDateTime, the month and day values begin at zero).

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See also

Date And Time Handling Overview