Why is LINQ distinct not giving distinct results?

Question

Aryan Kumar · Answer

There are a few reasons why the LINQ Distinct() method might not be giving distinct results. Here are some of the most common reasons:
The Distinct() method is not being used correctly. The Distinct() method takes a sequence as its input and returns a new sequence that contains only the distinct elements from the original sequence. The sequence must be an iterable collection, such as a Listandlt;T> or an IEnumerableandlt;T>.The elements in the sequence are not comparable. The Distinct() method uses the default equality comparer to compare the elements in the sequence. If the elements are not comparable, the
Distinct() method will not be able to remove the duplicates.The Distinct() method is being used with a custom comparer. If you are using a custom comparer with the
Distinct() method, make sure that the comparer is correctly implemented. The comparer must be able to compare two elements of the same type and return a value indicating whether the two elements are equal.
If you are still having trouble getting the Distinct() method to work, you can try using the
IEqualityComparer interface to provide a custom comparer. The 
IEqualityComparer interface defines two methods: Equals() and
GetHashCode(). The Equals() method is used to compare two elements and return a value indicating whether the two elements are equal. The
GetHashCode() method is used to return a hash code for an element. The hash code is used to quickly compare elements in a hash table.
Here is an example of how to use the IEqualityComparer interface to provide a custom comparer for the
Distinct() method:
C#
public class Person {
    public int Age { get; set; }
}
public class PersonComparer : IEqualityComparerandlt;Person> {
    public bool Equals(Person x, Person y) {
        return x.Age == y.Age;
    }
    public int GetHashCode(Person obj) {
        return obj.Age.GetHashCode();
    }
}
var people = new Listandlt;Person>();
people.Add(new Person { Age = 20 });
people.Add(new Person { Age = 30 });
people.Add(new Person { Age = 10 });
var distinctPeople = people.Distinct(new PersonComparer());
In this example, the PersonComparer class implements the IEqualityComparer interface and provides a custom comparer for the
Person class. The Equals() method compares the ages of two
Person objects and returns a value indicating whether the two objects are equal. The
GetHashCode() method returns a hash code for a Person object.
The Distinct() method is a powerful tool for removing duplicates from a sequence. However, it is important to use it correctly to avoid unexpected results.

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Why is LINQ distinct not giving distinct results?

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