Convert List<T> to HashTable

Question

I have a list:

public class tmp
{
    public int Id;
    public string Name;
    public string LName;
    public decimal Index;
}

List<tmp> lst = GetSomeData();

I want to convert this list to HashTable, and I want to specify Key and Value in Extension Method Argument. For example I may want to Key=Id and Value=Index or Key = Id + Index and Value = Name + LName. How can I do this?

Answer 1

You can use ToDictionary method:

var dic1 = list.ToDictionary(item => item.Id, 
                             item => item.Name);

var dic2 = list.ToDictionary(item => item.Id + item.Index, 
                             item => item.Name + item.LName);

You don't need to use Hashtable which comes from .NET 1.1, Dictionary is more type-safe.

Answer 2

In C# 4.0 you can use Dictionary<TKey, TValue>:

var dict = lst.ToDictionary(x => x.Id + x.Index, x => x.Name + x.LName);

But if you really want a Hashtable, pass that dictionary as a parameter in HashTable constructor...

var hashTable = new Hashtable(dict);