How do I determine the number of unique derived types in an array?

I have the following classes

Customer Class

abstract class Customer
{
    public int id;
    public string name;
    public double balance;
}

class NormalCustomer

class NormalCustomer: Customer
{
}

class SubscriberCustomer

class SubscriberCustomer:Customer
{
    public int LandMinutes;
    public int MobileMinutes;
}

If we create an array of Customers

Customer[] customers = new Customer[100];
customers[0]=new NormalCustomer();
customers[1] = new NormalCustomer();
customers[2] = new SubscriberCustomer();
customers[3] = new NormalCustomer();
customers[4] = new SubscriberCustomer();

The question is how do I know how many object in the array are NormalCustomers and how many object in the array are SubscriberCustomers?

Jon Skeet
people
quotationmark

I agree with Aleksey's answer - but if you want alternatives:

// Result is a sequence of Type/Count objects
var groupedByActualType = customers.GroupBy(
    x => x.GetType(), (type, values) => new { Type = type, Count = values.Count() });

Or:

var normal = customers.Count(c => c is NormalCustomer);
var subscribers = customers.Count(c => c is SubscriberCustomer);

people

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