using System;

using System.Collections.Generic;

using System.Linq;

using System.Linq.Expressions;

using System.Runtime.Remoting.Channels;

using System.Text;

using System.Text.RegularExpressions;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        float temp;

            Console.WriteLine("Enter the Temperature");

            if (!ReadTemparature(out temp))

            {

                if (!ReadTemparature(out temp))

                {

                    Console.WriteLine("Attempts Completed Application Closing");

                    Console.ReadLine();

                    Environment.Exit(0);

                }

            }

            char inputunits, outputunit;

            if (!ReadInputunit(out inputunits, "input"))

            {

                if (!ReadInputunit(out inputunits, "input"))

                {

                    Console.WriteLine("Attempts Completed Application Closing");

                    Console.ReadLine();

                    Environment.Exit(0);

                }

            }

            if (!ReadInputunit(out outputunit, "output"))

            {

                if (!ReadInputunit(out outputunit, "output"))

                {

                    Console.WriteLine("Attempts Completed Application Closing");

                    Console.ReadLine();

                    Environment.Exit(0);

                }

            }

            Convertvalue(temp, inputunits, outputunit);

            Console.ReadLine();

    }

     private static bool ValidateTemperatureUnit(char unit)

        {

            var reg = new Regex(@"[fFAaCc]");

            if (!reg.IsMatch(unit.ToString()))

            {

                Console.WriteLine("Enter a Valid Temperature Unit");

                return false;

            }

​

            return true;

        }

​

        private static bool ReadInputunit(out char inputunit, string param)

        {

            Console.WriteLine("Enter the {0} Temperature Unit as F for Fahrenheit, C for Celsius, K for Kelvin", param);

            if (!char.TryParse(Console.ReadLine(), out inputunit))

            {

                return false;

            }

            return ValidateTemperatureUnit(inputunit);

        }

​

        private static bool ReadTemparature(out float temp)

        {

            string inputtemp = Console.ReadLine();

            var regex = new Regex(@"^-?[0-9]*(?:\.[0-9]*)?$");

            if (!regex.IsMatch(inputtemp))

            {

                Console.WriteLine("Invalid Temperature, Enter a valid Temperature");

                temp = 0;

                return false;

            }

            temp = float.Parse(inputtemp);

            return true;

        }

​

        private static void Convertvalue(float temp, char input, char output)

        {

​

            switch (input)

            {

                case 'F':

                case 'f':

                    FarienhitConveriosn(temp, output);

                    break;

                case 'c':

                case 'C':

                    CentigradeConveriosn(temp, output);

                    break;

                case 'k':

                case 'K':

                    KelvinConveriosn(temp, output);

                    break;

            }

​

        }

​

        private static void FarienhitConveriosn(float temp, char output)

        {

            switch (output)

            {

                case 'F':

                case 'f':

                    Console.WriteLine("The Converted Temperature is {0} F", temp);

                    break;

                case 'C':

                case 'c':

                    Console.WriteLine("The Converted Temperature is {0} C", (temp - 32) * 5 / 9);

                    break;

                case 'K':

                case 'k':

                    Console.WriteLine("The Converted Temperature is {0} K", ((temp - 32) * 5 / 9) + 273.15);

                    break;

            }

        }

​

        private static void CentigradeConveriosn(float temp, char output)

        {

            switch (output)

            {

                case 'F':

                case 'f':

                    Console.WriteLine("The Converted Temperature is {0} F", temp * 9 / 5 + 32);

                    break;

                case 'C':

                case 'c':

                    Console.WriteLine("The Converted Temperature is {0} C", temp);

                    break;

                case 'K':

                case 'k':

                    Console.WriteLine("The Converted Temperature is {0} K", temp + 273.15);

                    break;

            }

        }

​

        private static void KelvinConveriosn(float temp, char output)

        {

            switch (output)

            {

                case 'F':

                case 'f':

                    Console.WriteLine("The Converted Temperature is {0} F", (temp - 273.15) * 9 / 5 + 32);

                    break;

                case 'C':

                case 'c':

                    Console.WriteLine("The Converted Temperature is {0} C", temp - 273.15);

                    break;

                case 'K':

                case 'k':

                    Console.WriteLine("The Converted Temperature is {0} K", temp);

                    break;

            }

        }

}