I have a class Customer that holds an array of class Order.
class Customer
{
public string firstname { get; set; }
public string lastname { get; set; }
public Order[] orders {get; set;}
}
I need to write a LINQ to find the total number of orders of all customers but I don't understand how to do it. For example I have created 8 customers and they have 3 orders each so I should print out 24.
Any help is appreciated!
You could use either of these.
// flattens order collection.
var result = custList.SelectMany(x => x.orders).Count();
or
var result = custList.Sum(x=>x.orders.Count());
var result = custList.SelectMany(x => x.orders).Count();
Order[] for each customer, and then counting the number of those - which will be the same as the number of customers. You'll need to use Sum or SelectMany as proposed in the answer above.You certainly can do it as var countOfOrders = customers.SelectMany(x => x.orders).Count();, but you many find it more readable as this:
var orders =
from c in customers
from o in c.orders
select o;
var countOfOrders = orders.Count();
You have to use SelectMany(). This method will makes one list of all orders. Then you can do count:
var allordersNumber = customers.SelectMany(x => x.Orders).Count();
Please read more about SelectMany() in MSDN.
