Initialize Dictionary<string,string> from List<string>

Question

Easiest way to do this, perhaps from an extension method? :

var MyDic = new Dictionary<string,string>{ "key1", "val1", "key2", "val2", ...}; 

Where the dictionary winds up with entries contain key and value pairs from the simple list of strings, alternating every other string being the key and values.

Answer 1

The alternation is a bit of a pain. Personally I'd just do it longhand:

var dictionary = new Dictionary<string, string>();
for (int index = 0; index < list.Count; index += 2)
{
    dictionary[list[index]] = list[index + 1];
}

You definitely can do it with LINQ, but it would be more complicated - I love using LINQ when it makes things simpler, but sometimes it's just not a great fit.

(Obviously you can wrap that up into an extension method.)

Note that you can use dictionary.Add(list[index], list[index + 1]) to throw an exception if there are duplicate keys - the above code will silently use the last occurrence of a particular key.

Answer 2

You can use a range that is half the length of the list, and ToDictionary to create the dictionary from items from the list:

Dictionary<string, string> dictionary =
  Enumerable.Range(0, list.Count / 2)
  .ToDictionary(i => list[i * 2], i => list[i * 2 + 1]);