filter an array in C#

Question

i have an array of objects (Car[] for example) and there is an IsAvailable Property on the object

i want to use the full array (where IsAvailable is true for some items and false for some others) as the input and return a new array which includes only the items that have IsAvailable = true.

Answer 1

If you're using C# 3.0 or better...

public Car[] Filter(Car[] input)
{
    return input.Where(c => c.IsAvailable).ToArray();
}

And if you don't have access to LINQ (you're using an older version of .NET)...

public Car[] Filter(Car[] input)
{
    List<Car> availableCars = new List<Car>();

    foreach(Car c in input)
    {
        if(c.IsAvailable)
            availableCars.Add(c);
    }

    return availableCars.ToArray();
}

Answer 2

Easiest way:

Car[] cars = //...
Car[] filtered = cars.Where(c => c.IsAvailable).ToArray();

Possibly More Efficient:

Car [] cars = //...
    List<Car> filteredList = new List<Car>();
    for(int i = 0; i < cars.Length; i++)
    {
        if(cars[i].IsAvailable)
           filteredList.Add(cars[i]);
    }
    Car[] filtered = filteredList.ToArray();

Answer 3

A simple solution is to create a new array, loop through the input array and add only those items which satisfy your conditions to the new array, and return the new array:

List<Car> available = new List<Car>();
foreach (Car c in cars) {
    if (c.IsAvailable) {
        available.add(c);
    }
}
//Here you can either just return the list, or create an array from it.

Answer 4

var available = from c in cars where c.IsAvailable == true select c;

Or

var available = cars.Where(c => c.IsAvailable == true);