C# Program to Print Nth Number in Fibonacci Series Iterative Approach

Write a C# Program to Print Nth Number in Fibonacci Series Iterative Approach?

What is Fibonacci Series?

Fibonacci series is a sequence of numbers in below order:
0, 1, 1, 2, 3, 5, 8, 13, 21, 34… The next number is found by adding up the two numbers before it.

The formula for calculating these numbers is:

F(n) = F(n-1) + F(n-2)

where:

F(n) is the term number.
F(n-1) is the previous term (n-1).
F(n-2) is the term before that (n-2).

it starts either with 0 or 1.

Different ways to print Fibonacci Series in C#?

In C#, there are several ways to print Fibonacci Series.

1. Iterative Approach
2. Recursion Approach

Iterative Approach :

This is the simplest way of generating Fibonacci seres in C#.

namespace ConsoleApplication
{
    class Program
    {
        static int FibonacciSeries(int n)
        {
            int firstnumber = 0, secondnumber = 1, result = 0;

            if (n == 0) return 0; //To return the first Fibonacci number
            if (n == 1) return 1; //To return the second Fibonacci number

            for (int i = 2; i <= n; i++)
            {
                result = firstnumber + secondnumber;
                firstnumber = secondnumber;
                secondnumber = result;
            }
            return result;
        }
        static void Main(string[] args)
        {
            Console.Write("Enter the length of the Fibonacci Series: ");
            int length = Convert.ToInt32(Console.ReadLine());

            for (int i = 0; i < length; i++)
            {
                Console.Write("{0} ", FibonacciSeries(i));
            }
            Console.ReadKey();
        }
    }
}


Output:

Enter the length of the Fibonacci Series: 12

0112358 13 21 34 55 89.