CODEWITHSUNDEEP
c#asp.net-mvc
k80sg
k80sg

Reputation: 2473

Adding items to List

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.

Upvotes: 1

Views: 167

Answers (3)

Adam Houldsworth
Adam Houldsworth

Reputation: 64467

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";

Upvotes: 3

Jon Skeet
Jon Skeet

Reputation: 1499810

It's not clear why you're using dynamic here to start with, to be honest. But if you used

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

it would have the same effect.

Note that it's genres.Add, not Genre.Add.

I'd also suggest that if you create a Genre constructor taking the name, it will make the code simpler - or if you want to still make the name part explicit, you could create a Genre.FromName static method.

Upvotes: 3

Yuriy Faktorovich
Yuriy Faktorovich

Reputation: 68667

In compiled terms none. It's actually syntax sugar for

dynamic genres = new List<Genre();
genres.Add(new Genre...

This is what I assume you meant, since Genre.Add(string) isn't described.

Upvotes: 1

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