Essential C# Equals and GetHashCode  Suggest an edit

Equals and GetHashCode in IEqualityComparator

For given type Person:

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
    public string Clothes { get; set; }
}

List<Person> persons = new List<Person>
{
    new Person{ Name = "Jon", Age = 20, Clothes = "some clothes"},
    new Person{ Name = "Dave", Age = 20, Clothes = "some other clothes"},
    new Person{ Name = "Jon", Age = 20, Clothes = ""}
};

var distinctPersons = persons.Distinct().ToList(); // distinctPersons has Count = 3

But defining Equals and GetHashCode into an IEqualityComparator :

public class PersonComparator : IEqualityComparer<Person>
{
    public bool Equals(Person x, Person y)
    {
        return x.Name == y.Name && x.Age == y.Age; // the clothes are not important when comparing two persons;
    }
		public int GetHashCode(Person obj) { return obj.Name.GetHashCode() * obj.Age; }
}

var distinctPersons = persons.Distinct(new PersonComparator()).ToList(); // distinctPersons has Count = 2

Note that for this query, two objects have been considered equal if both the Equals returned true and the GetHashCode have returned the same hash code for the two persons.


Table Of Contents
6 Equals and GetHashCode
22 Enum
25 GUID
107 Stream
108 Timers
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