CSHARP

C# get key by value Dict

var myKey = myDict.FirstOrDefault(x => x.Value == "myValue").Key;
// return the first key finded in the dict associated to this value

c# dictionary get value by key

 Dictionary<string, string> dict = new Dictionary<string, string>();
 dict.Add("UserID", "test");
 string userIDFromDictionaryByKey = dict["UserID"];

c# dictionary get key by value

            Dictionary<string, string> dict = new Dictionary<string, string>()
              {
                {"1", "one"},
                {"2", "two"},
                {"3", "three"}
              };
            foreach (var item in dict)
            {
                if(item.Value == "One")
                {
                    var firstElementKey = item.Key;
                  	Console.WriteLine(firstElementKey);
                }
            }