How do I get the list of keys in a Dictionary?

Question

I only want the Keys and not the Values of a Dictionary.

I haven\'t been able to get any code to do this yet. Using another array proved to be too much work as I use

Answer 1

You should be able to just look at .Keys:

    Dictionary<string, int> data = new Dictionary<string, int>();
    data.Add("abc", 123);
    data.Add("def", 456);
    foreach (string key in data.Keys)
    {
        Console.WriteLine(key);
    }

Answer 2

Marc Gravell's answer should work for you. myDictionary.Keys returns an object that implements ICollection<TKey>, IEnumerable<TKey> and their non-generic counterparts.

I just wanted to add that if you plan on accessing the value as well, you could loop through the dictionary like this (modified example):

Dictionary<string, int> data = new Dictionary<string, int>();
data.Add("abc", 123);
data.Add("def", 456);

foreach (KeyValuePair<string, int> item in data)
{
    Console.WriteLine(item.Key + ": " + item.Value);
}

Answer 3

Or like this:

List< KeyValuePair< string, int > > theList =
    new List< KeyValuePair< string,int > >(this.yourDictionary);

for ( int i = 0; i < theList.Count; i++)
{ 
  // the key
  Console.WriteLine(theList[i].Key);
}

Answer 4

To get list of all keys

using System.Linq;
List<String> myKeys = myDict.Keys.ToList();

System.Linq is supported in .Net framework 3.5 or above. See the below links if you face any issue in using System.Linq

Visual Studio Does not recognize System.Linq

System.Linq Namespace

Answer 5

I can't believe all these convoluted answers. Assuming the key is of type: string (or use 'var' if you're a lazy developer): -

List<string> listOfKeys = theCollection.Keys.ToList();

Answer 6

For a hybrid dictionary, I use this:

List<string> keys = new List<string>(dictionary.Count);
keys.AddRange(dictionary.Keys.Cast<string>());