Using the 'new' modifier with interfaces at a given index like 'var b = new ISomeInterface[0];', what does it mean?

Question

I've come across the following C# syntax for the first time, I would have discarded it as a syntax error except that VS is absolutely happy with it and compiles.

var a = new ISomeInterface[0];

The interface is declared as

public interface ISomeInterface
{
}

Links to further reading are also highly appreciated.

Move your mouse over the `var` keyword: it'll show you the actual type (i.e. an array) — ken2k, Aug 12 '14 at 12:01

score 4 · Accepted Answer · answered Aug 12 '14 at 11:55

You've created an array of ISomeInterface.

This is the same as declaring any other array, such as:

string[] a = new string[0];

I kinda did a double-take on that at first too, because at first glance it appeared the code was instantiating an interface, something you can't normally do.

score 2 · Answer 2 · answered Aug 12 '14 at 11:55

2

It is creating a new array (zero-length), not a new instance of the interface. Incidentally, you can actually new an interface... under the right conditions ;p (COM attributes)

answered Aug 12 '14 at 11:55

Marc Gravell

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I don't know if I'm more honored to have my question answered by Marc Gravell himself or more ashamed in realising I have asked such a silly question! Anyway thanks! =) – Giuseppe Romagnuolo Aug 12 '14 at 12:10

Using the 'new' modifier with interfaces at a given index like 'var b = new ISomeInterface[0];', what does it mean?

2 Answers2