Merging dictionaries in C#

Question

What\'s the best way to merge 2 or more dictionaries (Dictionary) in C#? (3.0 features like LINQ are fine).

I\'m thinking of a method signa

Answer 1

Merging using an extension method. It does not throw exception when there are duplicate keys, but replaces those keys with keys from the second dictionary.

internal static class DictionaryExtensions
{
    public static Dictionary Merge(this Dictionary first, Dictionary second)
    {
        if (first == null) throw new ArgumentNullException("first");
        if (second == null) throw new ArgumentNullException("second");

        var merged = new Dictionary();
        first.ToList().ForEach(kv => merged[kv.Key] = kv.Value);
        second.ToList().ForEach(kv => merged[kv.Key] = kv.Value);

        return merged;
    }
}

Usage:

Dictionary merged = first.Merge(second);