IEqualityComparator 中的 Equals 和 GetHashCode

对于给定类型 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

但是将 Equals 和 GetHashCode 定义为 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

请注意，对于此查询，如果 Equals 返回 true 并且 GetHashCode 已为两个人返回相同的哈希码，则认为两个对象相等。