Question

I was going a through a MVC tutorial when I bump into this:

public ActionResult Index()
{
    dynamic genres = new List<Genre> {
        new Genre { Name = "Disco" },
        new Genre { Name = "Jazz" },
        new Genre { Name = "Rock" }
    };
    return View(genres);
}

What is the difference if I use Genre.Add("Disco");… instead. Thanks.

Answer 1

_{I presume you mean the difference between that and genres.Add (the List<T>.Add method) as Genre.Add might be a static method on Genre or an instance method on a Genre variable, neither of which have been posted.}

There is no behavioural difference in the final code, it is only a visual difference.

Not sure why you are using dynamic (perhaps you are looking for var?), but the difference is that this is called collection initialization syntax, basically sugar over calling .Add manually:

var genres = new List<Genre> {
    new Genre { Name = "Disco" },
    new Genre { Name = "Jazz" },
    new Genre { Name = "Rock" }
};

Is equivalent to:

var genres = new List<Genre>();
genres.Add(new Genre { Name = "Disco" });
genres.Add(new Genre { Name = "Jazz" });
genres.Add(new Genre { Name = "Rock" });

The compiler outputs the .Add for you in your case.

Whats the difference between these three ways of creating a new List<string> in C#?

Also in your example, you are seeing the object initializer syntax with:

new Genre { Name = "Disco" }

Which equates to:

var g = new Genre();
g.Name = "Disco";