C#

int[] NumberCollection = Enumerable.Range(startNum,Count).ToArray<int>();
string primeNumbers = string.Join(",", from number in NumberCollection
                                       where (IsPrime(number)==true)
                                       select number);

private static bool IsPrime(int number)
      {
          for (int i = 2; i < number; i++)
              if (number % i == 0) return false;
          return true;
      }

class Program
{
    static void Main(string[] args)
    {
        if (args.Length > 0)
        {
            var v = File.ReadLines("dictionary.txt");

            var v1 = args[2];

            var v2 = args[3];

            var first = v.Where(w => w == v1).First();

            var last = v.Where(w => w == v2).First();

            var l = Array.IndexOf(v.ToArray(), first);

            var l2 = Array.IndexOf(v.ToArray(), last);

            var l3 = l2 - l;

            var results = v.Skip(l).Take(l3);

            foreach (var result in results)
            {
                Console.WriteLine(result);
            }
        }
        else
        {
            Console.ForegroundColor = ConsoleColor.DarkRed;
            Console.WriteLine("Arguments invalid");
        }
    }
}

// Please provide written answers to the questions below.
// 1. What is this code doing?
// 2. Comment on the quality of this code / how could you improve this implementation?
// 3. How could you verify the behaviour is correct?

#include <stdio.h>
#include <conio.h>
void main()
{
    int n,i;
    long s;
    scanf ("%d" ,&n);
    s=0;
    i=1;
    while (i<=n)
    {
        s=s+i;
        i=i+1;
    }
    printf("%ld",s);
}