C# Get all keys from a list of dictionaries-CodePudding

I basically want to know how to write this (Extract all keys from a list of dictionaries) in C#.

I have a list of dictionaries which have all unique keys.

I want to extract all of them into a list of string (as the key is string).

private List<Dictionary<string, string>> dictList = new List<Dictionary<string, string>>
{
     new Dictionary<string, string>() { { "a", "b" } },
     new Dictionary<string, string>() { { "c", "d" } },
};

private void GetDictListKeys()
{
    List<string> keyList = new List<string>();
    foreach(var dict in dictList)
    {
        keyList.Add(dict.Keys.ToString());
    }
}

Thank you.

CodePudding user response：

You want to flatten your enumerable of keys and dump it into a collection (HashSet used cause you mentioned duplicates, and because that's also what your linked answer used in Python):

var allKeys = dictList.SelectMany(d => d.Keys).ToHashSet();

CodePudding user response：

You can create another foreach loop inside yours:

 foreach (Dictionary<string,string> dict in dictList)
            {
                foreach(string key in dict.Keys)
                {
                    keyList.Add(key);                 
                }
            }

CodePudding user response：

You can use AddRange.

    foreach (var dict in dictList)
    {
        keyList.AddRange(dict.Keys);
    }