Answer to Question #272284 in C# for chi

Question

Write a program that generates and displays the Fibonacci sequences numbers of n (as input). In Fibonacci, the current third number is the sum of two previous numbers. Apply three solutions using the three loop statements: Sample input/output dialogue: Enter a no. 9 Fibonacci series: 1 1 2 3 5 8 13 21 34

1st Solution using for loop

2nd Solution – using while loop

3rd Solution-­‐ using do while loop

Answer 1

using System;
using System.Text;

namespace ConsoleAppFibonacciSequences
{
    class Program
    {
        static void Main(string[] args)
        {
            int number;
            int[] result;
            Console.WriteLine("Please enter a positive number for calculate Fibonacci sequences:");
            if (int.TryParse(Console.ReadLine(), out number))
            {
                if (number < 0)
                {
                    Console.WriteLine("The entered number must be positive.");
                }
                else
                {
                    result = FibonacciSequencesUsingForLoop(number);
                    Console.WriteLine($"The result of a calculation using a 'for' loop is {ArrayToString(result)}.");
                    result = FibonacciSequencesUsingWhileLoop(number);
                    Console.WriteLine($"The result of a calculation using a 'while' loop is {ArrayToString(result)}.");
                    result = FibonacciSequencesUsingDoWhileLoop(number);
                    Console.WriteLine($"The result of a calculation using a 'do while' loop is {ArrayToString(result)}.");
                }
            }
            else
            {
                Console.WriteLine("The entered value cannot be converted to a number.");
            }
            Console.ReadKey();
        }
        static int[] FibonacciSequencesUsingForLoop(int n)
        {
            if (n < 3)
            {
                return FibonacciSequencesWhenNumLessThanThree(n);
            }
            else
            {
                int[] result = new int[n];
                result[0] = 1;
                result[1] = 1;
                for (int i = 2; i < n; i++)
                {
                    result[i] = result[i - 2] + result[i - 1];
                }
                return result;
            }
        }
        static int[] FibonacciSequencesUsingWhileLoop(int n)
        {
            if (n < 3)
            {
                return FibonacciSequencesWhenNumLessThanThree(n);
            }
            else
            {
                int[] result = new int[n];
                result[0] = 1;
                result[1] = 1;
                int i = 2;
                while (i < n)
                {
                    result[i] = result[i - 2] + result[i - 1];
                    i++;
                }
                return result;
            }
        }
        static int[] FibonacciSequencesUsingDoWhileLoop(int n)
        {
            if (n < 3)
            {
                return FibonacciSequencesWhenNumLessThanThree(n);
            }
            else
            {
                int[] result = new int[n];
                result[0] = 1;
                result[1] = 1;
                int i = 2;
                do
                {
                    result[i] = result[i - 2] + result[i - 1];
                    i++;
                }
                while (i < n);
                return result;
            }
        }
        //Since the first numbers up to three in the Fibonacci sequence do not require calculation, we will move the work with these numbers into a separate method.
        private static int[] FibonacciSequencesWhenNumLessThanThree(int n)
        {
            if (n < 2) // if n=0 or n=1 return array single element n
            {
                return new int[1] { n };
            }
            else
            {
                return new int[2] { 1, 1 };
            }
        }
        // This method converts an int array to a string separated by whitespaces.
        private static string ArrayToString(int[] array)
        {
            StringBuilder sb = new StringBuilder();
            foreach (int i in array)
            {
                sb.Append(i + " ");
            }
            sb.Remove(sb.Length - 1, 1); // remove the last space
            return sb.ToString();
        }
    }
}