EssenNote/Program.cs

/*
    Copyright (c) 2015 Muhammad Moaz Imtiaz.
    
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

using System;

namespace EssenNote
{
	class MainClass
	{
		public static int Main (string[] args)
		{
			try
			{
				Console.Write("Total Weight: ");
				double weight = double.Parse(Console.ReadLine());
				Console.Write("Total Carbohydrates: ");
				double carbs = double.Parse(Console.ReadLine());
				Console.Write("Sugars: ");
				double sugars = double.Parse(Console.ReadLine());
				Console.Write("Total Fat: ");
				double fats = double.Parse(Console.ReadLine());
				Console.Write("Total Protein: ");
				double protein = double.Parse(Console.ReadLine());

				double sugarPercent = (100*sugars) / weight;
				double fatPercent = (900*fats)/(9*fats+4*(protein+carbs));
				double overallGrade = PercentGrade(sugarPercent, fatPercent);
				Console.WriteLine(LetterGrade(overallGrade) + "\t" + Math.Round(overallGrade*100)/100 + "%");

				return 0;
			}
			catch(Exception e) {
				Console.Error.WriteLine ("Error: " + e.GetType ().ToString () + " occurred.");
				Console.Error.WriteLine ("Description: " + e.Message);
				return -1;
			}
		}

		protected static double PercentGrade (double sugarPercent, double fatPercent)
		{
			double _sugarPercent = 100 - sugarPercent;
			double _fatPercent = 100 - fatPercent;
			double resultantGrade = 2*((_sugarPercent * _fatPercent) / (_sugarPercent+_fatPercent));
			return resultantGrade;
		}

		protected static string LetterGrade (double overallGrade)
		{
			overallGrade += .5;
			if (overallGrade < 60)
				return "E";
			else {
				string mainGrade = new string[] { "D", "C", "B", "A" , "A" }[(int)Math.Floor(overallGrade/10)-6];
				mainGrade += (overallGrade % 10 < 3 && overallGrade != 100) ? "-" : (overallGrade % 10 >= 8 || overallGrade == 100) ? "+" : "";
				return mainGrade;
			}
		}
	}
}