Chapter 65: Linq to Objects

WHERE clause.

When the above code is compiled and executed, it produces the following result:

Generating an Ordered List

var list = from car in cars orderby car ascending select car;

Sometimes it is useful to sort the returned data. The orderby clause will cause the elements to be sorted according to the default comparer for the type being sorted.

When the above code is compiled and executed, it produces the following result:

Working with a custom type

In this example, a typed list is created, populated, and then queried

public class Car

{

public String Name { get; private set; } public int UnitsSold { get; private set; }

public Car(string name, int unitsSold)

{

Name = name; UnitsSold = unitsSold;

}

}

class Program

{

static void Main(string[] args)

{

var car1 = new Car("VW Golf", 270952); var car2 = new Car("Opel Astra", 56079); var car3 = new Car("Audi A4", 52493); var car4 = new Car("Ford Focus", 51677); var car5 = new Car("Seat Leon", 42125);

var car6 = new Car("VW Passat", 97586); var car7 = new Car("VW Polo", 69867);

var car8 = new Car("Mercedes C-Class", 67549);

var cars = new List<Car> {

car1, car2, car3, car4, car5, car6, car7, car8 }; var list = from car in cars

select car.Name;

foreach (var entry in list)

{

Console.WriteLine(entry);

}

Console.ReadLine();

}

}

When the above code is compiled and executed, it produces the following result:

Until now the examples don't seem amazing as one can just iterate through the array to do basically the same. However, with the few examples below you can see how to create more complex queries with LINQ to Objects and achieve more with a lot less of code.

In the example below we can select cars that have been sold over 60000 units and sort them over the number of units sold:

var list = from car in cars

where car.UnitsSold > 60000 orderby car.UnitsSold descending select car;

StringBuilder sb = new StringBuilder();

foreach (var entry in list)

{

sb.AppendLine($"{entry.Name} - {entry.UnitsSold}");

}

Console.WriteLine(sb.ToString());

When the above code is compiled and executed, it produces the following result:

In the example below we can select cars that have sold an odd number of units and order them alphabetically over its name:

var list = from car in cars

where car.UnitsSold % 2 != 0 orderby car.Name ascending select car;

When the above code is compiled and executed, it produces the following result: