using System;
using System.Collections.Generic;
using System.Text;

//
// Name: Sebastian 'gonX' Jensen
// Date: 4. Nov 09
// Program: A simple Fahrenheit from/to Celcius converter
// Known to compile fine in: Microsoft Visual Express C# 2008
// Comments:    In this program I've used simple commands which should be fairly straightforward to understand.
//              Please notice that I've moved Main() to the bottom of the document so that it does not complain
//              that it's missing some functions that I'm calling from Main(). Yes, I could have assigned them
//              earlier in the program, but this is less confusing to look at.
//              Please throw me a PM on Overclock.net if you do not understand parts of my code - my username is gonX.
//

namespace switcheslawl
{
    class Program
    {
        // Here's an example of how Main() is not the first variable in the program.
        static void toFahrenheit()
        {
            // Let's assign the variables we need. We use double so that we don't get unnecessary rounding.
            string temporary;
            double input;
            double temperature;

            // Clear it so that it doesn't look messy.
            Console.Clear();

            // Here I'll be telling the user to input his temperature in degrees celcius.
            // Please notice that I am not using Console.WriteLine(), but instead Console.Write()
            // I'm using a temporary variable as calculating with a string is troublesome,
            // it is parsed to a double throughout the code though.
            // This is what makes C# different from C++ - in C++ I would not have needed to parse it.
            Console.Write("Please enter the temperature in °C: ");
            temporary = Console.ReadLine();
            input = double.Parse(temporary);
            temperature = input * 1.8 + 32;

            // The :N2 tells the program to only output 2 decimals. They're rounded off, which is not that
            // good for people who actively work with numbers, but it'll work for most people.
            Console.Write("\n{0 :N2} °C is {1 :N2} °F\nPress a button to continue\n", input, temperature);
            Console.ReadKey();
        }

        static void toCelcius()
        {
            // All this is the same as in the toFahrenheit() static, except that the formula for calculating is different.
            string temporary;
            double input;
            double temperature;
            Console.Clear();
            Console.Write("Please enter the temperature in °F: ");
            temporary = Console.ReadLine();
            input = double.Parse(temporary);
            temperature = (input - 32) / 1.8;
            Console.Write("\n{0 :N2} °F is {1 :N2} °C\nPress a button to continue\n", input, temperature);
            Console.ReadKey();
        }
        static void Main()
        {
            // Here I have to assign option to 0, otherwise it'd complain about option not being assigned
            string option = "0";

            // I can type "stop" to stop the program.
            while (option != "stop")
            {
                Console.Clear();
                Console.WriteLine("What do you want to calculate to?\n\nF. To Fahrenheit\nC. To Celcius\nstop to stop.");
                option = Console.ReadLine();

                // Most people should be acquainted with switches if they've been programming before. This is fairly similar to C++ syntax.
                switch (option.ToLower())
                {
                    case "f":
                        toFahrenheit();
                        break;
                    case "c":
                        toCelcius();
                        break;
                    default:
                        option = "stop";
                        break;
                }
            }
        }
    }
}

string temporary = "";
double input = 0;
double temperature = 0;

//You can also keep multiple variables of the same type on one line
string temporary = "";
double input = 0, temperature = 0;

// TryParse takes a string and outputs to a double, while returning a boolean value
// Create a bool variable to test whether the conversion was successful
bool convert = double.TryParse(temporary, out input);

// If the conversion was successful and the bool is true, complete the method
if (convert)
{
    temperature = input * 1.8 + 32;
    Console.Write("\n{0 :N2} °C is {1 :N2} °F\nPress a button to continue\n", input, temperature);
    Console.ReadKey();
}
// If the conversion failed and the bool is false, display an error message
else
{
    Console.WriteLine("You must enter a valid number. Press key to start over.");
    Console.ReadKey();
    // Run the same method
    toFarenheit();
}

class TemperatureConverter
{
    public double ToFahrenheit() { ... }
    public double ToCelcius() { ... }
}

void Main()
{
    TemperatureConverter converter = new TemperatureConverter();

    // read temp and scale from user...

    double result = converter.ToXXX();

    // display temp to user...
}