Creating the GetHashCode method in C#
.net, c#, gethashcode, hashcode
Solution
`System.Array` does not override `GetHashCode` or `Equals`, so they use reference equality. Therefore, you shouldn't call them.
To implement `GetHashCode`, see this question.
To implement `Equals`, use the `SequenceEqual` extension method.
EDIT: On .Net 2.0, you'll have to write your own version of `SequenceEqual`, like this:
public static bool SequenceEquals<T>(IList<T> first, IList<T> second) {
if (first == second) return true;
if (first == null || second == null) return false;
if (first.Count != second.Count) return false;
for (int i = 0; i < first.Count; i++)
if (!first[i].Equals(second[i]))
return false;
return true;
}
You could write it to take `IEnumerable<T>` instead of `IList<T>`, but it'd be somewhat slower because it wouldn't be able to exit early if the parameters have different sizes.
Problem
What is the best way to create your own GetHashCode method for a class in C#? Suppose I have a simple class (which overrides the Equals method), as follows: ``` class Test { public string[] names; public double[] values; public override bool Equals(object obj) { return (obj is Test) && this.Equals((Test)obj); } public bool Equals(Test t) { return names.Equals(t.names) && values.Equals(t.values); } } ``` Should I use the default code for the GetHashCode method? ``` public override int GetHashCode() { return base.GetHashCode(); } ``` Should I base the method on the contents of my class? ``` public override int GetHashCode() { return names.GetHashCode() + values.GetHashCode() ; } ``` Or should I do something else?