Question

How to get a IDictionnay form a IList

Answer 1

You can use Linq to easily get a Dictionary from a List by using the ToDictionary extension method and supplying an expression to get the key – e.g.

internal class Program
{
    private static void Main(string[] args)
    {
        IList<Person> list = new List<Person> {new Person("Bob", 40), new Person("Jill", 35)};
        IDictionary<string, Person> dictionary = list.ToDictionary(x => x.Name);
    }
}

public class Person
{
    private readonly int _age;
    private readonly string _name;

    public Person(string name, int age)
    {
        _name = name;
        _age = age;
    }

    public int Age
    {
        get { return _age; }
    }

    public string Name
    {
        get { return _name; }
    }
}

Alternatively, as Jon pointed out, if you need to use a different value for the Dictionary entries, you can also specify a second expression to get the value – as follows:

IDictionary<string, int> dictionary2 = list.ToDictionary(x => x.Name, x => x.Age);