using System;
using System.Linq;
namespace pc.linq03
{
class Program
{
static void Main(string[] args)
{
var nums = Enumerable.Range(0, 10);
var result1 = nums.OrderByDescending(n => n);
var result2 = from n in nums
orderby n descending
select n;
Array.ForEach(result1.ToArray(), n => Console.Write(n + " "));
Console.WriteLine();
Array.ForEach(result2.ToArray(), n => Console.Write(n+ " "));
Console.WriteLine();
}
}
}
Now the above is a simple usage of ordering collection data.
if we are trying to order a collection that contains custom objects, those objects have to implement the IComparable interface.
using System;
using System.Linq;
namespace pc.linq03
{
class Person : IComparable<Person>
{
public string Name { get; set; }
public int
BirthYear { get; set; }
public Person(string Name, int BirthYear)
{
this.Name = Name;
this.BirthYear = BirthYear;
}
public override string
ToString() { return $"{Name} {BirthYear}"; }
public int
CompareTo(Person other)
{
if (BirthYear == other.BirthYear)
return 0;
else if (BirthYear
< other.BirthYear)
return 1;
return -1;
}
}
class Program
{
static void Main(string[] args)
{
var ppl = new Person[] { new Person("pawel", 1984),
new Person("Marin", 1983), new Person("Magda", 1984),
new Person("Tomek",1988), new Person("Ivan", 1987),
new Person("Trish", 1989), new Person("Jake", 1988)};
var result1 = ppl.OrderByDescending(p => p);
var result2 = from p in ppl
orderby p descending
select p;
Array.ForEach(result1.ToArray(), n => Console.Write(n + ", "));
Console.WriteLine();
Array.ForEach(result2.ToArray(), n => Console.Write(n + ", "));
Console.WriteLine();
}
}
}
If our person class didn't implement the IComparable interface the when trying to order our collection we'd get an exception.
