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?
6 Answers
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.
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.
Use this code:
Enumerable.Repeat(0d, 25).ToList();
new List<double>(new double[25]); //Array elements default to 0
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]);
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.
For more complex types:
List<Customer> listOfCustomers =
new List<Customer> {
{ Id = 1, Name="Dave", City="Sarasota" },
{ Id = 2, Name="John", City="Tampa" },
{ Id = 3, Name="Abe", City="Miami" }
};
from here: David Hayden's Blog
