I’ve been thinking about this question for a bit and after a bit of consideration I agree that implementing IEquatable<T> and IComparable<T> should only be done on sealed types. I went back and forth for a bit but then I thought of the following test. Under what circumstances should the following ever return false? IMHO, … Read more
The whole situation is vexing. C# has too many ways to express equality and inequality: the == != > < >= <= operators (which are logically static methods) the Equals static method (which calls the virtual method), the Equals virtual method, the ReferenceEquals method The IComparable and IEquatable interfaces They all have subtly different semantics … Read more
Yes, you should implement both. If you implement one, any code that depends on the other will fail. There is lots of code that uses either IComparable or IComparable<T> but not both, so implementing both ensure your code will work with such code.
All types in .NET support the Object.Equals() method which, by default, compares two types for reference equality. However, sometimes, it also desirable to be able to compare two types for structural equality. The best example of this is arrays, which with .NET 4 now implement the IStructuralEquatable interface. This makes it possible to distinguish whether … Read more
As the name suggests, IComparable<T> reads out I’m comparable. IComparable<T> when defined for T lets you compare the current instance with another instance of same type. IComparer<T> reads out I’m a comparer, I compare. IComparer<T> is used to compare any two instances of T, typically outside the scope of the instances of T. As to … Read more
You should not define IComparable yourself. It is already defined. Rather, you need to implement IComparable on your BankAccount class. Where you defined the class BankAccount, make sure it implements the IComparable interface. Then write BankAccount.CompareTo to compare the balance amounts of the two objects. public class BankAccount : IComparable<BankAccount> { […] public int CompareTo(BankAccount … Read more
IComparable doesn’t overload the >= operator. You should use value.CompareTo(_minimumValue) >= 0
Well they are not quite the same thing as IComparer<T> is implemented on a type that is capable of comparing two different objects while IComparable<T> is implemented on types that are able to compare themselves with other instances of the same type. I tend to use IComparable<T> for times when I need to know how … Read more
IEquatable tests whether two objects are equal. IComparable imposes a total ordering on the objects being compared. For example, IEquatable would tell you that 5 is not equal to 7. IComparable would tell you that 5 comes before 7.