How to elegantly populate a heterogeneous array in c#

Question

I have 3 different classes (1 parent and 2 children), and I have created a heterogeneous array:

Parent[] parentArray =  new Parent[9];

I would like to populate this array with 3 Parent objects, 3 child1 objects, and 3 child2 objects, in that order.

I would like to know if there is a more elegant way to do it than just doing this:

parentArray[0] = new Parent();

parentArray[1] = new Parent();

parentArray[2] = new Parent();

parentArray[3] = new Child1();

parentArray[4] = new Child1();

....

parentArray[9] = new Child2();

Thanks!

Answer 1

Like this?

var parentArray = new Parent[]
{
    new Parent(),
    new Parent(),
    new Parent(),
    new Child1(),
    ...
};

Answer 2

In this situation, you want to perform a certain number of actions repeatedly. Loops are commonly used to do this. Because you're initializing an array, for loops are a good fit, as they expose an integer that can be used to index the array. In your scenario, you can use three such loops.

Parent[] parentArray = new Parent[9];

for (int i = 0; i < 3; i++)
{
    parentArray[i] = new Parent();
}

for (int i = 3; i < 6; i++)
{
    parentArray[i] = new Child1();
}

for (int i = 6; i < 9; i++)
{
    parentArray[i] = new Child2();
}

Answer 3

Personal i just think you should use the object initializer. However for sheer boredom you can use Linq and a generic factory method.

// Given
public static IEnumerable<T> Factory<T>(int count) where T : Parent, new() 
     => Enumerable.Range(0, count).Select(x => new T());

...

// Usage
var array = Factory<Parent>(3)
              .Union(Factory<Child1>(3))
              .Union(Factory<Child2>(3))
              .ToArray();