Instead of extending a type to implement IComparable to allow sorting, you can create a separate class that knows how to compare objects of that type and use the new class to do the sorting.
Here’s an example of sorting objects of type Person using a custom Compare method. To start with, we define a new class that implements IComparer.
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| public class PersonSorter : IComparer{ public int Compare(object o1, object o2) { Person p1 = o1 as Person; Person p2 = o2 as Person; // Sort by LastName, then by FirstName (ignore case) int compare = p1.LastName.ToLower().CompareTo(p2.LastName.ToLower()); if (compare == 0) compare = p1.FirstName.ToLower().CompareTo(p2.FirstName.ToLower()); return compare; }} |
Now we can sort using this compare function by passing an instance of the IComparer class into the Sort method.
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| Person[] folks = new Person[4];folks[0] = new Person("Bronte", "Emily");folks[1] = new Person("Bronte", "Charlotte");folks[2] = new Person("Tennyson", "Alfred");folks[3] = new Person("Mailer", "Norman");Array.Sort(folks, new PersonSorter()); |