Calculate Years, Months, weeks and Days

Question

In my application, a user enters two dates. A scheduled start date, and a scheduled end date. We have to take those dates, and populate 4 fields, based on the difference.

Answer 1

 public partial class Age1 : System.Web.UI.Page
    {
        private int Years;
        private int Months;
        private int Days;
        DateTime Cday;
        DateTime Bday;


        protected void Page_Load(object sender, EventArgs e)
        {
            txtCurrentDate.Enabled = false;
            txtCurrentDate.Text = DateTime.Now.ToString("g");
            Cday = Convert.ToDateTime(txtCurrentDate.Text);
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            Bday = Convert.ToDateTime(txtBirthdate.Text);
            AgeCaluclation(Bday, Cday);
            txtBirthdate.Text = "";
            txtCurrentDate.Text = "";
            lblAge.Text = this.Years+"  Years "+this.Months+"  Months " +this.Days+ "Days";
        }

        private Age1 AgeCaluclation(DateTime Bday, DateTime Cday)
        {

            if ((Cday.Year - Bday.Year) > 0 || 
               (((Cday.Year - Bday.Year) == 0) && 
               ((Bday.Month < Cday.Month) ||
               ((Bday.Month == Cday.Month) && 
               (Bday.Day <= Cday.Day)))))
            {

                int DaysInBdayMonth = DateTime.DaysInMonth(Bday.Year, Bday.Month);
                int DaysRemain = Cday.Day + (DaysInBdayMonth - Bday.Day);

                    if(Cday.Month > Bday.Month)
                    {
                        this.Years = Cday.Year - Bday.Year;
                        this.Months = Cday.Month - (Bday.Month + 1) + Math.Abs(DaysRemain / DaysInBdayMonth);
                        this.Days = (DaysRemain % DaysInBdayMonth + DaysInBdayMonth) % DaysInBdayMonth;
                    }
                    else if (Cday.Month == Bday.Month)
                    {
                        if (Cday.Day >= Bday.Day)
                        {
                            this.Years = Cday.Year - Bday.Year;
                            this.Months = 0;
                            this.Days = Cday.Day - Bday.Day;
                        }
                        else
                        {
                            this.Years = (Cday.Year - 1) - Bday.Year;
                            this.Months = 11;
                            this.Days = DateTime.DaysInMonth(Bday.Year, Bday.Month) - (Bday.Day - Cday.Day);

                        }
                    }
                    else
                    {
                        this.Years = (Cday.Year - 1) - Bday.Year;
                        this.Months = Cday.Month + (11 - Bday.Month) + Math.Abs(DaysRemain / DaysInBdayMonth);
                        this.Days = (DaysRemain % DaysInBdayMonth + DaysInBdayMonth) % DaysInBdayMonth;
                    }
            }
            else
            {
                throw new ArgumentException("Birthday date must be earlier than current date");
            }
            return this;
        }

    }