Hashtable with multiple values for single key

Question

I want to store multiple values in single key like:

HashTable obj = new HashTable();
obj.Add(\"1\", \"test\");
obj.Add(\"1\", \"Test1\");

Right

Answer 1

You're looking for a Lookup, which can natively store multiple values for each key.

As pointed out this only works for a fixed list since you cannot add entries to a lookup once you have created it.

public class LookupEntry
{
    public string Key { get; set; }
    public string Value { get; set; }
}

var list = new List(new LookupEntry [] 
                                    {
                                    new LookupEntry() {Key="1", Value="Car" }, 
                                    new LookupEntry() {Key="1", Value="Truck"},
                                    new LookupEntry() {Key="2", Value="Duck"}
                                    });


var lookup = list.ToLookup(x => x.Key, x => x.Value);
var all1s = lookup["1"].ToList();