GroupBy partitions a list of numbers by their remainder when divided by 5. : GroupBy « LINQ « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. LINQ
3. GroupBy

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class MainClass {
    public static void Main() {

        int[] numbers = { 5, 4, 1, 3, 9 };

        var numberGroups =
            from n in numbers
            group n by n % 5 into g
            select new { Remainder = g.Key, Numbers = g };

        foreach (var g in numberGroups) {
            Console.WriteLine("Numbers with a remainder of {0} when divided by 5:", g.Remainder);
            foreach (var n in g.Numbers) {
                Console.WriteLine(n);
            }
        }
    }
}