Use LINQ to get items in one List<>, that are not in another List<>
Asked 07 September, 2021
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Votes

I would assume there's a simple LINQ query to do this, I'm just not exactly sure how.

Given this piece of code:

class Program
{
    static void Main(string[] args)
    {
        List<Person> peopleList1 = new List<Person>();
        peopleList1.Add(new Person() { ID = 1 });
        peopleList1.Add(new Person() { ID = 2 });
        peopleList1.Add(new Person() { ID = 3 });

        List<Person> peopleList2 = new List<Person>();
        peopleList2.Add(new Person() { ID = 1 });
        peopleList2.Add(new Person() { ID = 2 });
        peopleList2.Add(new Person() { ID = 3 });
        peopleList2.Add(new Person() { ID = 4 });
        peopleList2.Add(new Person() { ID = 5 });
    }
}

class Person
{
    public int ID { get; set; }
}

I would like to perform a LINQ query to give me all of the people in peopleList2 that are not in peopleList1.

This example should give me two people (ID = 4 & ID = 5)

10 Answer