What's the Difference between Session.Add("key",value) and Session["key"] = value?

Question

Can somebody please explain to me the difference between:

Session.Add("name",txtName.text); and Session["name"] = txtName.text;

It was an interview question and I answered that both store data in key = "Value" format like Dictionary class in C#.

Am I right, or is there any difference?

Answer 1

Looking at the code for HttpSessionState shows us that they are in fact the same.

public sealed class HttpSessionState : ICollection, IEnumerable {     private IHttpSessionState _container; ...     public void Add(string name, object value)     {         this._container[name] = value;     }      public object this[string name]     {         get         {             return this._container[name];         }         set         {             this._container[name] = value;         }     } ... } 

As for them both

Storing data in key = "Value" format like Dictionary class in C#.

They actually store the result in an IHttpSessionState object.

Answer 2

The two code snippets you posted are one and the same in functionality. Both update (or create if it doesn't exist) a certain Session object defined by the key.

Session.Add("name",txtName.text);

is the same as:

Session["name"] = txtName.text;

The first is method-based, where the second is string indexer-based.

Both overwrite the previous value held by the key.