Failed to compare 2 objects in the array (compare with inheritance and shared)

Question

Situation: I have 2 classes (one base class and one derived class that inherits the base class). Both classes implement the CompareTo method, so I can sort the list.

The base class contains the following values:

day, month  and year

The derived class inherits those 3 and adds 2 more:

hours and minutes

The problem is that I am adding Date and DateTime objects to the list, which it sorts correctly only on the day of the month and year.

The DateTime object that contains (day, month, year, hours, and minutes) correctly sorts the base properties when hours and minutes are not sorted at all.

But when I comment out all Date objects and add only DateTime objects, all sorting is done correctly ...

" 2 ", Virtual override calss ( CompareTo)

:

Program.cs:

    List<Date> slDate = new List<Date>();

    slDate.Add(new Date(1, 2, 2011));
    slDate.Add(new Date(06, 01, 2000));

    slDate.Add(new DateTijd(10, 11, 2011, 5, 20));              
    slDate.Add(new DateTijd(8, 11, 2011, 20, 01));
    slDate.Add(new DateTijd(8, 11, 2011, 20, 30));


    slDate.Sort();

    for (int i = 0; i < slDate.Count; i++)
    {
        Console.WriteLine("{0}", slDate[i].ToString());
    }

Date.cs( ):

    //Constructor
    public Date(int d, int m, int j)
    {
      // .....
    }


    public virtual int CompareTo(Date d)
    {
        int res;

        res = this.Year.CompareTo(d.Year); //Year is a property
        if (res != 0) return res;

        res = this.Month.CompareTo(d.Month);
        if (res != 0) return res;

        res = this.Day.CompareTo(d.Day);
        if (res != 0) return res;

        return 0;
    }

}/*Date*/

DateTime.cs( ):

    //Constructor
    public DateTime(int d, int m, int j, int h, int min): base(d, m, j)
    {
        //....
    }

    class DateTime: Date //derived class
    {
        //code ....

        public override int CompareTo(Date d) 
        {
            DateTime dt = (DateTime)d;
            int res;

            res = this.Hours.CompareTo(dt.Hours);
            if (res != 0) return res;

            res = this.Minutes.CompareTo(dt.Minutes);
            if (res != 0) return res;

            return 0; 
        }

    }

Answer 1

-, IComparable.
-, Date DateTime ( ).

public override int CompareTo(object obj) 
{
   var comparison = base.CompareTo(obj);
   if(comparison == 0 && obj is DateTime)
   {
      DateTime dt = (DateTime)obj;
      int res;

      res = this.Hours.CompareTo(dt.Hours);
      if (res != 0) return res;

      res = this.Minutes.CompareTo(dt.Minutes);
      if (res != 0) return res;

      return 0; 
    }
    return comparison;
}

, . , , , .

:

 public int DoCompare(Date firstDate, Date secondDate)
 {
    int res;

    res = firstDate.Year.CompareTo(secondDate.Year); //Year is a property
    if (res != 0) return res;

    res = firstDate.Month.CompareTo(secondDate.Month);
    if (res != 0) return res;

    res = firstDate.Day.CompareTo(secondDate.Day);
    if (res != 0) return res;

    return 0;
 }

:

var test = DoCompare(new DateTime(8,11,2011,20,30), new Date(1, 2, 2011));

. DateTime, . , , DateTime , ( ), ).

:

public int DoCompareDateTimes(DateTime firstDate, DateTime secondDate)
{
 int res;

 res = firstDate.Year.CompareTo(secondDate.Year); //Year is a property
 if (res != 0) return res;

 res = firstDate.Month.CompareTo(secondDate.Month);
 if (res != 0) return res;

 res = firstDate.Day.CompareTo(secondDate.Day);
 if (res != 0) return res;

 res = this.Hours.CompareTo(dt.Hours);
 if (res != 0) return res;

 res = this.Minutes.CompareTo(dt.Minutes);
 if (res != 0) return res;

 return 0;
}

var test = DoCompareDateTimes(new DateTime(8,11,2011,20,30), new Date(1, 2, 2011));

. DateTime, ( DateTime, DateTime Date not).

Answer 2

Date: Icomparable<Date>