Is it possible to calculate the Chinese Zodiac, or must I use a lookup table?

Question

I'm building an application that will tell your Chinese sign. I looked around but only found charts (from 1900 to 2020), and no logic to create something more dynamic. Is there no logic for determining a Chinese zodiac?

Accepted Answer

Does that answer your question:

```
public string ChineseZodiac(System.DateTime date)
{
    System.Globalization.EastAsianLunisolarCalendar cc = 
          new System.Globalization.ChineseLunisolarCalendar();
    int sexagenaryYear = cc.GetSexagenaryYear(date);
    int terrestrialBranch = cc.GetTerrestrialBranch(sexagenaryYear);

// string[] years = "rat,ox,tiger,hare,dragon,snake,horse,sheep,monkey,fowl,dog,pig".Split(',');
    // string[] years = "Rat,Ox,Tiger,Rabbit,Dragon,Snake,Horse,Goat,Monkey,Rooster,Dog,Pig".Split(',');
    // string[] years = new string[]{ "rat", "ox", "tiger", "hare", "dragon", "snake", "horse", "sheep", "monkey", "fowl", "dog", "pig" };    
    string[] years = new string[]{ "Rat", "Ox", "Tiger", "Rabbit", "Dragon", "Snake", "Horse", "Goat", "Monkey", "Rooster", "Dog", "Pig" };

return years[terrestrialBranch - 1];
} // End Function ChineseZodiac
```

Fore those that need the source code for another programming language: I've ripped the corresponding sources out of .NET Framwork, here: https://gist.github.com/ststeiger/709354299a457e2d79b06d0127096fee

Edit: I ported this to JavaScript:

```
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.ChineseZodiac = void 0;
var DateTimeKind;
(function (DateTimeKind) {
    DateTimeKind[DateTimeKind["Unspecified"] = 0] = "Unspecified";
    DateTimeKind[DateTimeKind["Utc"] = 1] = "Utc";
    DateTimeKind[DateTimeKind["Local"] = 2] = "Local";
})(DateTimeKind || (DateTimeKind = {}));
var GregorianCalendar = (function () {
    function GregorianCalendar() {
    }
    GregorianCalendar.prototype.GetYear = function (time) {
        var ticks = time.JavaScriptTicks;
        var dt = new Date(ticks);
        return dt.getUTCFullYear();
    };
    GregorianCalendar.prototype.GetMonth = function (time) {
        var ticks = time.JavaScriptTicks;
        var dt = new Date(ticks);
        return (dt.getUTCMonth() + 1);
    };
    GregorianCalendar.prototype.GetDayOfMonth = function (time) {
        var ticks = time.JavaScriptTicks;
        var dt = new Date(ticks);
        return dt.getUTCDate();
    };
    return GregorianCalendar;
}());
var DotNetDateTime = (function () {
    function DotNetDateTime(ticks, dt) {
        this.m_ticks = 0;
        this.m_ticks = ticks;
    }
    DotNetDateTime.fromJsDate = function (dt) {
        var jsTicks = dt.getTime();
        var dotNetJsbaseTicks = 621355968000000000;
        var tenK = 10000;
        var dotTicks = dotNetJsbaseTicks + jsTicks * tenK;
        return new DotNetDateTime(dotTicks, DateTimeKind.Unspecified);
    };
    Object.defineProperty(DotNetDateTime.prototype, "Ticks", {
        get: function () {
            return this.m_ticks;
        },
        enumerable: false,
        configurable: true
    });
    Object.defineProperty(DotNetDateTime.prototype, "JavaScriptTicks", {
        get: function () {
            var dotNetJsbaseTicks = 621355968000000000;
            var dotNetTicksSince1970 = this.m_ticks - dotNetJsbaseTicks;
            var jsTicks = parseInt((dotNetTicksSince1970 / 10000).toString(), 10);
            return jsTicks;
        },
        enumerable: false,
        configurable: true
    });
    return DotNetDateTime;
}());
var MinLunisolarYear = 1901;
var MaxLunisolarYear = 2100;
var DaysPerYear = 365;
var DaysPer4Years = DaysPerYear * 4 + 1;
var DaysPer100Years = DaysPer4Years * 25 - 1;
var DaysPer400Years = DaysPer100Years * 4 + 1;
var DaysTo10000 = DaysPer400Years * 25 - 366;
var TicksPerMillisecond = 10000;
var TicksPerSecond = TicksPerMillisecond * 1000;
var TicksPerMinute = TicksPerSecond * 60;
var TicksPerHour = TicksPerMinute * 60;
var TicksPerDay = TicksPerHour * 24;
var MinTicks = 0;
var MaxTicks = DaysTo10000 * TicksPerDay - 1;
var MinValue = new DotNetDateTime(MinTicks, DateTimeKind.Unspecified);
var MaxValue = new DotNetDateTime(MaxTicks, DateTimeKind.Unspecified);
var Jan1Month = 1;
var Jan1Date = 2;
var nDaysPerMonth = 3;
var s_daysToMonth365 = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
var s_daysToMonth366 = [0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335];
var s_yinfo = [
    [0, 2, 19, 19168],
    [0, 2, 8, 42352],
    [5, 1, 29, 21096],
    [0, 2, 16, 53856],
    [0, 2, 4, 55632],
    [4, 1, 25, 27304],
    [0, 2, 13, 22176],
    [0, 2, 2, 39632],
    [2, 1, 22, 19176],
    [0, 2, 10, 19168],
    [6, 1, 30, 42200],
    [0, 2, 18, 42192],
    [0, 2, 6, 53840],
    [5, 1, 26, 54568],
    [0, 2, 14, 46400],
    [0, 2, 3, 54944],
    [2, 1, 23, 38608],
    [0, 2, 11, 38320],
    [7, 2, 1, 18872],
    [0, 2, 20, 18800],
    [0, 2, 8, 42160],
    [5, 1, 28, 45656],
    [0, 2, 16, 27216],
    [0, 2, 5, 27968],
    [4, 1, 24, 44456],
    [0, 2, 13, 11104],
    [0, 2, 2, 38256],
    [2, 1, 23, 18808],
    [0, 2, 10, 18800],
    [6, 1, 30, 25776],
    [0, 2, 17, 54432],
    [0, 2, 6, 59984],
    [5, 1, 26, 27976],
    [0, 2, 14, 23248],
    [0, 2, 4, 11104],
    [3, 1, 24, 37744],
    [0, 2, 11, 37600],…

Is it possible to calculate the Chinese Zodiac, or must I use a lookup table?

Solution

Problem