gregorian_to_jalali.cs

using System;

namespace Date {
  public class Convertor {
    struct DateStruct {
      public int year;
      public int month;
      public int day;
    };

    private DateStruct GregorianToJalali(int year, int month, int day) {
      DateStruct result;

      int[] array = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };

      if (year <= 1600) {
        year -= 621;
        result.year = 0;
      } else {
        year -= 1600;
        result.year = 979;
      }

      int temp = (year > 2) ? (year + 1) : year;
      int days = ((int)((temp + 3) / 4)) + (365 * year) - ((int)((temp + 99) / 100)) - 80 +
        array[month - 1] + ((int)((temp + 399) / 400)) + day;

      result.year += 33 * ((int)(days / 12053));
      days %= 12053;
      result.year += 4 * ((int)(days / 1461));
      days %= 1461;

      if (days > 365) {
        result.year += (int)((days - 1) / 365);
        days = (days - 1) % 365;
      }

      result.month = (days < 186) ? 1 + (int)(days / 31) : 7 + (int)((days - 186) / 30);

      result.day = 1 + ((days < 186) ? (days % 31) : ((days - 186) % 30));

      return result;
    }

    public String GregorianToJalaliStr(int year, int month, int day) {
      DateStruct result = GregorianToJalali(year, month, day);
      string res = string.Format("{0:d}:{1:d}:{2:d}", result.year, result.month, result.day);
      return res;
    }

  }
}

public class Program {
  public static void Main() {
    Date.Convertor cv = new Date.Convertor();
    Console.WriteLine(cv.GregorianToJalaliStr(2022, 01, 07));
    Console.WriteLine(cv.GregorianToJalaliStr(2022, 1, 7));
  }
}