Auto-initializing C# lists

I am creating a new C# List (List<double>). Is there a way, other than to do a loop over the list, to initialize all the starting values to 0?

Solution 1:

In addition to the functional solutions provided (using the static methods on the Enumerable class), you can pass an array of doubles in the constructor.

var tenDoubles = new List<double>(new double[10]);

This works because the default value of an double is already 0, and probably performs slightly better.

Solution 2:

You can use the initializer:

var listInt = new List<int> {4, 5, 6, 7};
var listString = new List<string> {"string1", "hello", "world"};
var listCustomObjects = new List<Animal> {new Cat(), new Dog(), new Horse()};

So you could be using this:

var listInt = new List<double> {0.0, 0.0, 0.0, 0.0};

Otherwise, using the default constructor, the List will be empty.

Solution 3:

Use this code:

Enumerable.Repeat(0d, 25).ToList();
new List<double>(new double[25]);     //Array elements default to 0

Solution 4:

One possibility is to use Enumerable.Range:

int capacity;
var list = Enumerable.Range(0, capacity).Select(i => 0d).ToList();

Another is:

int capacity;
var list = new List<double>(new double[capacity]);

Solution 5:

A bit late, but maybe still of interest: Using LINQ, try

var initializedList = new double[10].ToList()

...hopefully avoiding copying the list (that's up to LINQ now).

This should be a comment to Michael Meadows' answer, but I'm lacking reputation.