Most concise way to initialize a C# hashtable

c# hashtable
RexE picture RexE · May 8, 2009 · Viewed 20.9k times · Source

Does C# allow hashtables to be populated in one-line expressions? I am thinking of something equivalent to the below Python:

mydict = {"a": 23, "b": 45, "c": 67, "d": 89}

In other words, is there an alternative to setting each key-value pair in a separate expression?

Answer

Andrew Hare picture Andrew Hare · May 8, 2009

C# 3 has a language extension called collection initializers which allow you to initialize the values of a collection in one statement.

Here is an example using a Dictionary<,>:

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        var dict = new Dictionary<string, int>
        {
            {"a", 23}, {"b", 45}, {"c", 67}, {"d", 89}
        };
    }
}

This language extension is supported by the C# 3 compiler and any type that implements IEnumerable and has a public Add method.

If you are interested I would suggest you read this question I asked here on StackOverflow as to why the C# team implemented this language extension in such a curious manner (once you read the excellent answers to the question you will see that it makes a lot of sense).

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