Is there any library or algorithm for Persian (Sha

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I want to convert Gregorian (western) date to Persian (Shamsi) date and vice versa for all versions of Android.

Is there any complete and reliable library or algorithm?

Answer 1

I have developed Android Shamsi datepicker widget with hijri - gerogian- shamsi event view: https://github.com/irshst/ir.shes.calendar

Answer 2

Create the calculateJalaliDate as function like so; and then return the Jalali date in String

public String calculateJalaliDate(){

    Calendar c = Calendar.getInstance();
    String jalaliDate,JalaliMonth;
    int jalaliYear,jalaliMonth,calculateMonth,jalaliDay=0,allDays=0;
    int day=c.get(Calendar.DAY_OF_MONTH);
    int month=c.get(Calendar.MONTH)+1;
    int year=c.get(Calendar.YEAR);

    switch (month){
        case 1: allDays=year*365+31+day;break;
        case 2: allDays=year*365+(31+28)+day;break;
        case 3: allDays=year*365+(31+28+31)+day;break;
        case 4: allDays=year*365+(31+28+31+30)+day;break;
        case 5: allDays=year*365+(31+28+31+30+31)+day;break;
        case 6: allDays=year*365+(31+28+31+30+31+30)+day;break;
        case 7: allDays=year*365+(31+28+31+30+31+30+31)+day;break;
        case 8: allDays=year*365+(31+28+31+30+31+30+31+31)+day;break;
        case 9: allDays=year*365+(31+28+31+30+31+30+31+31+30)+day;break;
        case 10: allDays=year*365+(31+28+31+30+31+30+31+31+30+31)+day;break;
        case 11: allDays=year*365+(31+28+31+30+31+30+31+31+30+31+30)+day;break;
        case 12: allDays=year*365+(31+28+31+30+31+30+31+31+30+31+30+31)+day;break;
    }

    //226899
    jalaliYear=( allDays - 227139 )/365+1;
    calculateMonth=( allDays - 227139 )%365;
    if(calculateMonth<32)jalaliMonth=1;
    else if((calculateMonth-31)<32){jalaliMonth=2;jalaliDay=calculateMonth-31;}
    else if((calculateMonth-62)<32){jalaliMonth=3;jalaliDay=calculateMonth-62;}
    else if((calculateMonth-93)<32){jalaliMonth=4;jalaliDay=calculateMonth-93;}
    else if((calculateMonth-124)<32){jalaliMonth=5;jalaliDay=calculateMonth-124;}
    else if((calculateMonth-155)<32){jalaliMonth=6;jalaliDay=calculateMonth-155;}
    else if((calculateMonth-186)<31){jalaliMonth=7;jalaliDay=calculateMonth-186;}
    else if((calculateMonth-216)<31){jalaliMonth=8;jalaliDay=calculateMonth-216;}
    else if((calculateMonth-246)<31){jalaliMonth=9;jalaliDay=calculateMonth-246;}
    else if((calculateMonth-276)<31){jalaliMonth=10;jalaliDay=calculateMonth-276;}
    else if((calculateMonth-306)<31){jalaliMonth=11;jalaliDay=calculateMonth-306;}
    else {
        jalaliMonth=12;
        if((jalaliYear%4)==0)jalaliDay=calculateMonth-336;
        else jalaliDay=calculateMonth-335;
    }



    /*switch (jalaliMonth){
        case 1:JalaliMonth="فروردین"; break;
        case 2:JalaliMonth="اردیبهشت"; break;
        case 3:JalaliMonth="خرداد"; break;
        case 4:JalaliMonth="تیر"; break;
        case 5:JalaliMonth="مرداد"; break;
        case 6:JalaliMonth="شهریور"; break;
        case 7:JalaliMonth="مهر"; break;
        case 8:JalaliMonth="آبان"; break;
        case 9:JalaliMonth="آذر"; break;
        case 10:JalaliMonth="دی"; break;
        case 11:JalaliMonth="بهمن"; break;
        case 12:JalaliMonth="اسفند"; break;
    }*/


    jalaliDate=String.valueOf(jalaliYear)+"/"+String.valueOf(jalaliMonth)+"/"+String.valueOf(jalaliDay);
    return jalaliDate;
}

Answer 3

I think this java class is easier to use and more reliable. I found it in Iranian forum, Iranians use Jalali Calendar and call it "Shamsi" that means Solar calendar. this is the Java class:

package MyUtil;

import java.util.Calendar;
import java.util.GregorianCalendar;

/**
 * Title: Calender Conversion class
 * Description: Convert Iranian (Jalali), Julian, and Gregorian dates to
 * each other
 * Public Methods Summary:
 * -----------------------
 * JavaSource_Calendar();
 * JavaSource_Calendar(int year, int month, int day);
 * int getIranianYear();
 * int getIranianMonth();
 * int getIranianDay();
 * int getGregorianYear();
 * int getGregorianMonth();
 * int getGregorianDay();
 * int getJulianYear();
 * int getJulianMonth();
 * int getJulianDay();
 * String getIranianDate();
 * String getGregorianDate();
 * String getJulianDate();
 * String getWeekDayStr();
 * String toString();
 * int getDayOfWeek();
 * void nextDay();
 * void nextDay(int days);
 * void previousDay();
 * void previousDay(int days);
 * void setIranianDate(int year, int month, int day);
 * void setGregorianDate(int year, int month, int day);
 * void setJulianDate(int year, int month, int day);
 */
public class CalendarTool {

    /**
     * JavaSource_Calendar:
     * The default constructor uses the current Gregorian date to initialize the
     * other private memebers of the class (Iranian and Julian dates).
     */
    public CalendarTool()
    {
        Calendar calendar = new GregorianCalendar();
        setGregorianDate(calendar.get(Calendar.YEAR),
                calendar.get(Calendar.MONTH)+1,
                calendar.get(Calendar.DAY_OF_MONTH));
    }

    /**
     * JavaSource_Calendar:
     * This constructor receives a Gregorian date and initializes the other private
     * members of the class accordingly.
     * @param year int
     * @param month int
     * @param day int
     */
    public CalendarTool(int year, int month, int day)
    {
        setGregorianDate(year,month,day);
    }

    /**
     * getIranianYear:
     * Returns the 'year' part of the Iranian date.
     * @return int
     */
    public int getIranianYear() {
        return irYear;
    }

    /**
     * getIranianMonth:
     * Returns the 'month' part of the Iranian date.
     * @return int
     */
    public int getIranianMonth() {
        return irMonth;
    }

    /**
     * getIranianDay:
     * Returns the 'day' part of the Iranian date.
     * @return int
     */
    public int getIranianDay() {
        return irDay;
    }

    /**
     * getGregorianYear:
     * Returns the 'year' part of the Gregorian date.
     * @return int
     */
    public int getGregorianYear() {
        return gYear;
    }

    /**
     * getGregorianMonth:
     * Returns the 'month' part of the Gregorian date.
     * @return int
     */
    public int getGregorianMonth() {
        return gMonth;
    }

    /**
     * getGregorianDay:
     * Returns the 'day' part of the Gregorian date.
     * @return int
     */
    public int getGregorianDay() {
        return gDay;
    }

    /**
     * getJulianYear:
     * Returns the 'year' part of the Julian date.
     * @return int
     */
    public int getJulianYear() {
        return juYear;
    }

    /**
     * getJulianMonth:
     * Returns the 'month' part of the Julian date.
     * @return int
     */
    public int getJulianMonth() {
        return juMonth;
    }

    /**
     * getJulianDay()
     * Returns the 'day' part of the Julian date.
     * @return int
     */
    public int getJulianDay() {
        return juDay;
    }

    /**
     * getIranianDate:
     * Returns a string version of Iranian date
     * @return String
     */
    public String getIranianDate()
    {
        return (irYear+"/"+irMonth+"/"+irDay);
    }

    /**
     * getGregorianDate:
     * Returns a string version of Gregorian date
     * @return String
     */
    public String getGregorianDate()
    {
        return (gYear+"/"+gMonth+"/"+gDay);
    }

    /**
     * getJulianDate:
     * Returns a string version of Julian date
     * @return String
     */
    public String getJulianDate()
    {
        return (juYear+"/"+juMonth+"/"+juDay);
    }

    /**
     * getWeekDayStr:
     * Returns the week day name.
     * @return String
     */
    public String getWeekDayStr()
    {
        String weekDayStr[]={
                "Monday",
                "Tuesday",
                "Wednesday",
                "Thursday",
                "Friday",
                "Saturday",
        "Sunday"};
        return (weekDayStr[getDayOfWeek()]);
    }

    /**
     * toString:
     * Overrides the default toString() method to return all dates.
     * @return String
     */
    public String toString()
    {
        return (getWeekDayStr()+
                ", Gregorian:["+getGregorianDate()+
                "], Julian:["+getJulianDate()+
                "], Iranian:["+getIranianDate()+"]");
    }


    /**
     * getDayOfWeek:
     * Returns the week day number. Monday=0..Sunday=6;
     * @return int
     */
    public int getDayOfWeek()
    {
        return (JDN % 7);
    }

    /**
     * nextDay:
     * Go to next julian day number (JDN) and adjusts the other dates.
     */
    public void nextDay()
    {
        JDN++;
        JDNToIranian();
        JDNToJulian();
        JDNToGregorian();
    }
    /**
     * nextDay:
     * Overload the nextDay() method to accept the number of days to go ahead and
     * adjusts the other dates accordingly.
     * @param days int
     */
    public void nextDay(int days)
    {
        JDN+=days;
        JDNToIranian();
        JDNToJulian();
        JDNToGregorian();
    }

    /**
     * previousDay:
     * Go to previous julian day number (JDN) and adjusts the otehr dates.
     */
    public void previousDay()
    {
        JDN--;
        JDNToIranian();
        JDNToJulian();
        JDNToGregorian();
    }

    /**
     * previousDay:
     * Overload the previousDay() method to accept the number of days to go backward
     * and adjusts the other dates accordingly.
     * @param days int
     */
    public void previousDay(int days)
    {
        JDN-=days;
        JDNToIranian();
        JDNToJulian();
        JDNToGregorian();
    }

    /**
     * setIranianDate:
     * Sets the date according to the Iranian calendar and adjusts the other dates.
     * @param year int
     * @param month int
     * @param day int
     */
    public void setIranianDate(int year, int month, int day)
    {
        irYear =year;
        irMonth = month;
        irDay = day;
        JDN = IranianDateToJDN();
        JDNToIranian();
        JDNToJulian();
        JDNToGregorian();
    }

    /**
     * setGregorianDate:
     * Sets the date according to the Gregorian calendar and adjusts the other dates.
     * @param year int
     * @param month int
     * @param day int
     */
    public void setGregorianDate(int year, int month, int day)
    {
        gYear = year;
        gMonth = month;
        gDay = day;
        JDN = gregorianDateToJDN(year,month,day);
        JDNToIranian();
        JDNToJulian();
        JDNToGregorian();
    }

    /**
     * setJulianDate:
     * Sets the date according to the Julian calendar and adjusts the other dates.
     * @param year int
     * @param month int
     * @param day int
     */
    public void setJulianDate(int year, int month, int day)
    {
        juYear = year;
        juMonth = month;
        juDay = day;
        JDN = julianDateToJDN(year,month,day);
        JDNToIranian();
        JDNToJulian();
        JDNToGregorian();
    }

    /**
     * IranianCalendar:
     * This method determines if the Iranian (Jalali) year is leap (366-day long)
     * or is the common year (365 days), and finds the day in March (Gregorian
     * Calendar)of the first day of the Iranian year ('irYear').Iranian year (irYear)
     * ranges from (-61 to 3177).This method will set the following private data
     * members as follows:
     * leap: Number of years since the last leap year (0 to 4)
     * Gy: Gregorian year of the begining of Iranian year
     * march: The March day of Farvardin the 1st (first day of jaYear)
     */
    private void IranianCalendar()
    {
        // Iranian years starting the 33-year rule
        int Breaks[]=
            {-61, 9, 38, 199, 426, 686, 756, 818,1111,1181,
                1210,1635,2060,2097,2192,2262,2324,2394,2456,3178} ;
        int jm,N,leapJ,leapG,jp,j,jump;
        gYear = irYear + 621;
        leapJ = -14;
        jp = Breaks[0];
        // Find the limiting years for the Iranian year 'irYear'
        j=1;
        do{
            jm=Breaks[j];
            jump = jm-jp;
            if (irYear >= jm)
            {
                leapJ += (jump / 33 * 8 + (jump % 33) / 4);
                jp = jm;
            }
            j++;
        } while ((j<20) && (irYear >= jm));
        N = irYear - jp;
        // Find the number of leap years from AD 621 to the begining of the current
        // Iranian year in the Iranian (Jalali) calendar
        leapJ += (N/33 * 8 + ((N % 33) +3)/4);
        if ( ((jump % 33) == 4 ) && ((jump-N)==4))
            leapJ++;
        // And the same in the Gregorian date of Farvardin the first
        leapG = gYear/4 - ((gYear /100 + 1) * 3 / 4) - 150;
        march = 20 + leapJ - leapG;
        // Find how many years have passed since the last leap year
        if ( (jump - N) < 6 )
            N = N - jump + ((jump + 4)/33 * 33);
        leap = (((N+1) % 33)-1) % 4;
        if (leap == -1)
            leap = 4;
    }


    /**
     * IsLeap:
     * This method determines if the Iranian (Jalali) year is leap (366-day long)
     * or is the common year (365 days), and finds the day in March (Gregorian
     * Calendar)of the first day of the Iranian year ('irYear').Iranian year (irYear)
     * ranges from (-61 to 3177).This method will set the following private data
     * members as follows:
     * leap: Number of years since the last leap year (0 to 4)
     * Gy: Gregorian year of the begining of Iranian year
     * march: The March day of Farvardin the 1st (first day of jaYear)
     */
    public boolean IsLeap(int irYear1)
    {
        // Iranian years starting the 33-year rule
        int Breaks[]=
            {-61, 9, 38, 199, 426, 686, 756, 818,1111,1181,
                1210,1635,2060,2097,2192,2262,2324,2394,2456,3178} ;
        int jm,N,leapJ,leapG,jp,j,jump;
        gYear = irYear1 + 621;
        leapJ = -14;
        jp = Breaks[0];
        // Find the limiting years for the Iranian year 'irYear'
        j=1;
        do{
            jm=Breaks[j];
            jump = jm-jp;
            if (irYear1 >= jm)
            {
                leapJ += (jump / 33 * 8 + (jump % 33) / 4);
                jp = jm;
            }
            j++;
        } while ((j<20) && (irYear1 >= jm));
        N = irYear1 - jp;
        // Find the number of leap years from AD 621 to the begining of the current
        // Iranian year in the Iranian (Jalali) calendar
        leapJ += (N/33 * 8 + ((N % 33) +3)/4);
        if ( ((jump % 33) == 4 ) && ((jump-N)==4))
            leapJ++;
        // And the same in the Gregorian date of Farvardin the first
        leapG = gYear/4 - ((gYear /100 + 1) * 3 / 4) - 150;
        march = 20 + leapJ - leapG;
        // Find how many years have passed since the last leap year
        if ( (jump - N) < 6 )
            N = N - jump + ((jump + 4)/33 * 33);
        leap = (((N+1) % 33)-1) % 4;
        if (leap == -1)
            leap = 4;
        if (leap==4 || leap==0)
            return true;
        else
            return false;

    }



    /**
     * IranianDateToJDN:
     * Converts a date of the Iranian calendar to the Julian Day Number. It first
     * invokes the 'IranianCalender' private method to convert the Iranian date to
     * Gregorian date and then returns the Julian Day Number based on the Gregorian
     * date. The Iranian date is obtained from 'irYear'(1-3100),'irMonth'(1-12) and
     * 'irDay'(1-29/31).
     * @return long (Julian Day Number)
     */
    private int IranianDateToJDN()
    {
        IranianCalendar();
        return (gregorianDateToJDN(gYear,3,march)+ (irMonth-1) * 31 - irMonth/7 * (irMonth-7) + irDay -1);
    }

    /**
     * JDNToIranian:
     * Converts the current value of 'JDN' Julian Day Number to a date in the
     * Iranian calendar. The caller should make sure that the current value of
     * 'JDN' is set correctly. This method first converts the JDN to Gregorian
     * calendar and then to Iranian calendar.
     */
    private void JDNToIranian()
    {
        JDNToGregorian();
        irYear = gYear - 621;
        IranianCalendar(); // This invocation will update 'leap' and 'march'
        int JDN1F = gregorianDateToJDN(gYear,3,march);
        int k = JDN - JDN1F;
        if (k >= 0)
        {
            if (k <= 185)
            {
                irMonth = 1 + k/31;
                irDay = (k % 31) + 1;
                return;
            }
            else
                k -= 186;
        }
        else
        {
            irYear--;
            k += 179;
            if (leap == 1)
                k++;
        }
        irMonth = 7 + k/30;
        irDay = (k % 30) + 1;
    }


    /**
     * julianDateToJDN:
     * Calculates the julian day number (JDN) from Julian calendar dates. This
     * integer number corresponds to the noon of the date (i.e. 12 hours of
     * Universal Time). This method was tested to be good (valid) since 1 March,
     * -100100 (of both calendars) up to a few millions (10^6) years into the
     * future. The algorithm is based on D.A.Hatcher, Q.Jl.R.Astron.Soc. 25(1984),
     * 53-55 slightly modified by K.M. Borkowski, Post.Astron. 25(1987), 275-279.
     * @param year int
     * @param month int
     * @param day int
     * @return int
     */
    private int julianDateToJDN(int year, int month, int day)
    {
        return (year + (month - 8) / 6 + 100100) * 1461/4 + (153 * ((month+9) % 12) + 2)/5 + day - 34840408;
    }

    /**
     * JDNToJulian:
     * Calculates Julian calendar dates from the julian day number (JDN) for the
     * period since JDN=-34839655 (i.e. the year -100100 of both calendars) to
     * some millions (10^6) years ahead of the present. The algorithm is based on
     * D.A. Hatcher, Q.Jl.R.Astron.Soc. 25(1984), 53-55 slightly modified by K.M.
     * Borkowski, Post.Astron. 25(1987), 275-279).
     */
    private void JDNToJulian()
    {
        int j= 4 * JDN + 139361631;
        int i= ((j % 1461)/4) * 5 + 308;
        juDay = (i % 153) / 5 + 1;
        juMonth = ((i/153) % 12) + 1;
        juYear = j/1461 - 100100 + (8-juMonth)/6;
    }

    /**
     * gergorianDateToJDN:
     * Calculates the julian day number (JDN) from Gregorian calendar dates. This
     * integer number corresponds to the noon of the date (i.e. 12 hours of
     * Universal Time). This method was tested to be good (valid) since 1 March,
     * -100100 (of both calendars) up to a few millions (10^6) years into the
     * future. The algorithm is based on D.A.Hatcher, Q.Jl.R.Astron.Soc. 25(1984),
     * 53-55 slightly modified by K.M. Borkowski, Post.Astron. 25(1987), 275-279.
     * @param year int
     * @param month int
     * @param day int
     * @return int
     */
    private int gregorianDateToJDN(int year, int month, int day)
    {
        int jdn = (year + (month - 8) / 6 + 100100) * 1461/4 + (153 * ((month+9) % 12) + 2)/5 + day - 34840408;
        jdn = jdn - (year + 100100+(month-8)/6)/100*3/4+752;
        return (jdn);
    }
    /**
     * JDNToGregorian:
     * Calculates Gregorian calendar dates from the julian day number (JDN) for
     * the period since JDN=-34839655 (i.e. the year -100100 of both calendars) to
     * some millions (10^6) years ahead of the present. The algorithm is based on
     * D.A. Hatcher, Q.Jl.R.Astron.Soc. 25(1984), 53-55 slightly modified by K.M.
     * Borkowski, Post.Astron. 25(1987), 275-279).
     */
    private void JDNToGregorian()
    {
        int j= 4 * JDN + 139361631;
        j = j + (((((4* JDN [phone])/146097)*3)/4)*4-3908);
        int i= ((j % 1461)/4) * 5 + 308;
        gDay = (i % 153) / 5 + 1;
        gMonth = ((i/153) % 12) + 1;
        gYear = j/1461 - 100100 + (8-gMonth)/6;
    }


    private int irYear; // Year part of a Iranian date
    private int irMonth; // Month part of a Iranian date
    private int irDay; // Day part of a Iranian date
    private int gYear; // Year part of a Gregorian date
    private int gMonth; // Month part of a Gregorian date
    private int gDay; // Day part of a Gregorian date
    private int juYear; // Year part of a Julian date
    private int juMonth; // Month part of a Julian date
    private int juDay; // Day part of a Julian date
    private int leap; // Number of years since the last leap year (0 to 4)
    private int JDN; // Julian Day Number
    private int march; // The march day of Farvardin the first (First day of jaYear)
} // End of Class 'JavaSource_Calendar

You can easily set the Gregorian Day, Month and Year, then call "getIranianDate()" method to get the date in string format, just like the sample code below:

MyUtil.CalendarTool ct = new CalendarTool(2012,10,10);
System.out.println(ct.getIranianDate());

I hope it helps.

Answer 4

The newest version v3.10-2015g of my library Time4A (an Android adaptation of Time4J) contains support for the Jalali calendar. The library deploys the algorithm of Borkowski (valid until gregorian year 2129). Actually about 25 languages are supported for Persian months and eras (including Farsi and Pashto, based on CLDR-28).

Examples of usage:

// current date
PersianCalendar jalali = SystemClock.inLocalView().now(PersianCalendar.axis());
System.out.println(jalali); // AP-1394-08-04

// tomorrow
jalali = jalali.plus(CalendarDays.ONE);
System.out.println(jalali); // AP-1394-08-05

// localized format of tomorrow (English and Farsi)
ChronoFormatter<PersianCalendar> f =
    ChronoFormatter.ofStyle(DisplayMode.FULL, Locale.ENGLISH, PersianCalendar.axis());
Locale farsi = new Locale("fa");
System.out.println(f.format(jalali)); // Tuesday, Aban 5, 1394 AP
System.out.println(f.with(farsi).format(jalali)); // سه‌شنبه, آبان 5, 1394 ه‍.ش.

// shift back to month Farvardin and format the result
jalali = jalali.with(PersianCalendar.MONTH_OF_YEAR, PersianMonth.FARVARDIN);
System.out.println(f.format(jalali)); // Wednesday, Farvardin 5, 1394 AP
System.out.println(f.with(farsi).format(jalali)); // چهارشنبه, فروردین 5, 1394 ه‍.ش.

// conversion to gregorian date
System.out.println(jalali); // AP-1394-01-05
System.out.println(jalali.transform(PlainDate.class)); // 2015-03-25

// create new year in persian calendar and show gregorian counter part
jalali = PersianCalendar.of(1394, PersianMonth.FARVARDIN, 1);
System.out.println(jalali.transform(PlainDate.class)); // 2015-03-21

// create new year in gregorian calendar and show persian counter part
PlainDate gregorianDate = PlainDate.of(2015, Month.JANUARY, 1);
System.out.println(gregorianDate.transform(PersianCalendar.class)); // AP-1393-10-11

// delta between gregorian new year and persian new year
System.out.println(CalendarDays.between(gregorianDate, jalali).getAmount()); // 79

Interoperability with java.util.Date on Android

Since Time4A manages its own set of immutable types and is not based on the primary temporal type of Android, I show following bridge:

// Time4A => Android
PlainDate gdate = jalali.transform(PlainDate.class);
Moment m1 = gdate.atStartOfDay().inTimezone(ASIA.TEHRAN);
java.util.Date jud = TemporalType.JAVA_UTIL_DATE.from(m1);

// Android => Time4A
java.util.Date input = new java.util.Date();
Moment m2 = TemporalType.JAVA_UTIL_DATE.translate(input);
jalali = m2.toZonalTimestamp(ASIA.TEHRAN).toDate().transform(PersianCalendar.class);

Answer 5

this method is very exact and simply also support leap years

Explain:

step 1: time today is contain current time

step 2: create two array for gregorian and jalali day in months(g_days_in_month&j_days_in_month)

step 3: create variable for retention difference time between calendars (gy,gm,gd) and variable g_day_no for days of years.

step 4: insert day of month and collect with days.

step 5: convert days of years to jalili years (jy)

at the end : set jalali month from day number, set jalali day from jalali day of month array.

good luck.

    Time today = new Time(Time.getCurrentTimezone());
    today.setToNow();
    int Day = (today.monthDay);             // Day of the month (0-31)
    int Month = (today.month);              // Month (0-11)
    int Year = (today.year);                // Year

    String persianDate = GregorianToJalali(Year, Month+1, Day);

  private String GregorianToJalali(int g_y, int g_m, int g_d)
{

  int[] g_days_in_month = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  int[] j_days_in_month = {31, 31, 31, 31, 31, 31, 30, 30, 30, 30, 30, 29};

    int gy = g_y-1600;
    int gm = g_m-1;
    int gd = g_d-1;

        int g_day_no = 365*gy+div(gy+3,4)-div(gy+99,100)+div(gy+399,400);

        for (int i=0; i < gm; ++i)
          g_day_no += g_days_in_month[i];
        if (gm>1 && ((gy%4==0 && gy%100!=0) || (gy%400==0)))
         // leap and after Feb 
          g_day_no++;
        g_day_no += gd;

       int j_day_no = g_day_no-79;

        int j_np = div(j_day_no, 12053); //12053 = 365*33 + 32/4 
        j_day_no = j_day_no % 12053;

        int jy = 979+33*j_np+4*div(j_day_no,1461); // 1461 = 365*4 + 4/4 

        j_day_no %= 1461;

        if (j_day_no >= 366) {
          jy += div(j_day_no-1, 365);
          j_day_no = (j_day_no-1)%365;
        }

        int j;
        for (j=0; j < 11 && j_day_no >= j_days_in_month[j]; ++j)
          j_day_no -= j_days_in_month[j];
       int jm = j+1;
       int jd = j_day_no+1;


        String Result= jy+"/"+jm+"/"+jd;

        return (Result);
     }  


  private int div(float a, float b)
  {  
      return (int)(a/b); 
  }