/* .NET automatically associates the IComparable type to all object.
* Thus, all valueTypes and several .NET library classes inherit the IComparable interface.
* Note: Mismatch types cannot be compared.
* Note: In this example, different instance of the Order class can be compared with each other.
* So a order1 can be compared to a order2 to determine its sort order (1: after, 0: same, -1: before).
* Note: To compare a custom class created by you, you class must implement either or both of the generic/non-generic IComparable interface.
* Note: Just note that the generic version of the IComparable interface offers better performance than the non-generic one which requires boxing and unboxing via casting.
* */
static private void AdvancedCompareExample()
{
#region OrderV1 - Using generic IComparable version
OrderV1 obiOrder = new OrderV1
{
OrderId = 1,
OrderBy = "Obi",
OrderItemName = "PS4",
OrderDate = new DateTime(year: 2020, month: 07, day: 16, hour: 15, minute: 00, second: 00) //07/16/2020 @ 03:00 pm
};
OrderV1 kinisOrder = new OrderV1
{
OrderId = 1,
OrderBy = "Kinis",
OrderItemName = "Necklace",
OrderDate = new DateTime(year: 2020, month: 07, day: 16, hour: 20, minute: 30, second: 00)//07/16/2020 @ 08:30 pm
};
//An overload for CompareTo exist - one accepts Order, another accepts object. Because the Order class implemented both the generic and non-generic version of the IComparable interface.
var compareResult = obiOrder.CompareTo(kinisOrder);
switch (compareResult)
{
case 1: { Console.WriteLine("obiOrder was ordered after kinisOrder."); } break;
case 0: { Console.WriteLine("obiOrder was ordered same time as kinisOrder."); } break;
case -1: { Console.WriteLine("obiOrder was ordered before kinisOrder."); } break;
}
#endregion
#region OrderV2 - Using non-generic IComparable version
OrderV2 obiOrderV2 = new OrderV2
{
OrderId = 1,
OrderBy = "Obi",
OrderItemName = "PS4",
OrderDate = new DateTime(year: 2020, month: 07, day: 16, hour: 15, minute: 00, second: 00) //07/16/2020 @ 03:00 pm
};
OrderV2 kinisOrderV2 = new OrderV2
{
OrderId = 1,
OrderBy = "Kinis",
OrderItemName = "Necklace",
OrderDate = new DateTime(year: 2020, month: 07, day: 16, hour: 20, minute: 30, second: 00)//07/16/2020 @ 08:30 pm
};
//An overload for CompareTo exist - one accepts Order, another accepts object. Because the Order class implemented both the generic and non-generic version of the IComparable interface.
var compareResultV2 = obiOrderV2.CompareTo(kinisOrderV2);
switch (compareResultV2)
{
case 1: { Console.WriteLine("obiOrder was ordered after kinisOrder."); } break;
case 0: { Console.WriteLine("obiOrder was ordered same time as kinisOrder."); } break;
case -1: { Console.WriteLine("obiOrder was ordered before kinisOrder."); } break;
}
#endregion
}
/*
* This approach use the non-generic version of the IComparable interface. Consider using the non-generic version for better performance to avoid boxing and unboxing issues.
* Good when you don't know exactly what the comparing Type will be.
* Note: Do Not compare between the objects itself as this will force a recursive operation and a never ending execution. So avoid doing order1.CompareTo(order2)
* Note: Compare with properties in both objects to determine how the sort against each other. So order1.OrderDate.CompareTo(order2.OrderDate)
* */
public int CompareTo(object obj)
{
OrderV2 order2 = obj as OrderV2;
if (order2 is null) //if order to compare against is empty then return 1 to indicate order1 (Left hand) comes after or greater than the empty order2 (Right hand)
{
return(1); //meaning order1 comes after order2 (even though there wasn't an actual order2)
}
switch (this.OrderDate.CompareTo(order2.OrderDate))
{
case 1: { return(1); } //order1 comes after order2
case 0: { return(0); } //order1 is same position as order2
case -1: { return(-1); } //order1 comes before order2
}
throw new ArgumentException("Order cannot be sorted.");
}