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copied!<p>Because of the problems raised in this thread, I'm posting another reply showing what happens if you get it wrong... mainly, that you can't use the array's <code>GetHashCode()</code>; the correct behaviour is that no warnings are printed when you run it... switch the comments to fix it:</p> <pre><code>using System; using System.Collections.Generic; using System.Linq; static class Program { static void Main() { // first and second are logically equivalent SimpleTableRow<int> first = new SimpleTableRow<int>(1, 2, 3, 4, 5, 6), second = new SimpleTableRow<int>(1, 2, 3, 4, 5, 6); if (first.Equals(second) && first.GetHashCode() != second.GetHashCode()) { // proven Equals, but GetHashCode() disagrees Console.WriteLine("We have a problem"); } HashSet<SimpleTableRow<int>> set = new HashSet<SimpleTableRow<int>>(); set.Add(first); set.Add(second); // which confuses anything that uses hash algorithms if (set.Count != 1) Console.WriteLine("Yup, very bad indeed"); } } class SimpleTableRow<T> : IEquatable<SimpleTableRow<T>> { public SimpleTableRow(int id, params T[] values) { this.Id = id; this.Values = values; } public int Id { get; private set; } public T[] Values { get; private set; } public override int GetHashCode() // wrong { return Id.GetHashCode() ^ Values.GetHashCode(); } /* public override int GetHashCode() // right { int hash = Id; if (Values != null) { hash = (hash * 17) + Values.Length; foreach (T t in Values) { hash *= 17; if (t != null) hash = hash + t.GetHashCode(); } } return hash; } */ public override bool Equals(object obj) { return Equals(obj as SimpleTableRow<T>); } public bool Equals(SimpleTableRow<T> other) { // Check for null if (ReferenceEquals(other, null)) return false; // Check for same reference if (ReferenceEquals(this, other)) return true; // Check for same Id and same Values return Id == other.Id && Values.SequenceEqual(other.Values); } } </code></pre>

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