Following is the syntax for declaring a dictionary in C# :

Dictionary<int,string> NewDictionary = new Dictionary<int,string>();

Now elements can be added in this list using function :

NewDictionary.Add(1,“Name1”);

NewDictionary.Add(2,“Name2”);

Here 1 and 2 represents unique keys for vaules ‘Name1’ and ‘Name2’. The key is a unique value and same keys cannot exist in a dictionary.

For Example the below code will give a error because the key 1 is duplicated in the dictionary:

NewDictionary.Add(1,“Name1”);

NewDictionary.Add(1,“Name2”);

The image below shows the exception that occurs due to duplicate keys :