C# Fibonacci Series

By definition, the first two numbers in the Fibonacci sequence are 0 and 1, and each subsequent number is the sum of the previous two.

0,1,1,2,3,5,8,13...

A C# program that prints out first 6 fibonacci numbers

using System;

namespace ConsoleApplication4

{

    internal class Program

    {

        private static void Main(string[] args)

        {

            int[] fibonacci = GetFibonacci(6);

            for (int i = 0; i < fibonacci.Length; i++)

            {

                Console.WriteLine(fibonacci[i]);// 0 1 1 2 3 5

            }

        }

        private static int[] GetFibonacci(int i)

        {

            var fibonacciSeries = new int[i];

            //Initialize first two values

            fibonacciSeries[0] = 0;

            fibonacciSeries[1] = 1;

            for (int x = 2; x < i; x++)

            {

                fibonacciSeries[x] = fibonacciSeries[(x - 1)] + fibonacciSeries[(x - 2)];

            }

            return fibonacciSeries;

        }

    }

}

A C# program that prints out first 6 fibonacci numbers using an Iterator

using System;

using System.Collections.Generic;

namespace ConsoleApplication4

{

    internal class Program

    {

        private static void Main(string[] args)

        {

            IEnumerable<int> fibonacci = GetFibonacci(6);

            foreach (int f in fibonacci)

            {

                Console.WriteLine(f); // 0 1 1 2 3 5

            }

        }

        private static IEnumerable<int> GetFibonacci(int i)

        {

            var fibonacciSeries = new int[i];

            for (int x = 0; x < i; x++)

            {

                switch (x)

                {

                    case 0:

                        fibonacciSeries[0] = 0;

                        yield return fibonacciSeries[0];

                        break;

                    case 1:

                        fibonacciSeries[1] = 1;

                        yield return fibonacciSeries[1];

                        break;

                    default:

                        fibonacciSeries[x] = fibonacciSeries[(x - 1)] + fibonacciSeries[(x - 2)];

                        yield return fibonacciSeries[x];

                        break;

                }

            }

        }

    }

}