Reddit project 3e

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

namespace Third___Easy
{
    class Program
    {
        static TextReader input;
        static TextWriter output;
        static int step;

        static void Main(string[] args)
        {
            Initialize(args);
            string line = input.ReadLine();

            while (line.Length > 0)
            {
                StringBuilder outputLine = new StringBuilder(line.Length);
                foreach (char c in line)
                {
                    if (char.IsLower(c))
                    {
                        outputLine.Append(CaesarCypherLower(c));
                    }
                    else if (char.IsUpper(c))
                    {
                          outputLine.Append(CaesarCypherUpper(c));
                    }
                    else
                    {
                          outputLine.Append(CaesarCypherOther(c));
                    }
                }
                output.WriteLine(outputLine);
                line = input.ReadLine();
            }
        }

        private static void Initialize(string[] args)
        {
            input = Console.In;
            output = Console.Out;
            step = 1;

            for (int i = 0; i < args.Length; i++)
            {
                if (args[i] == "-i")
                {
                    input = new StreamReader(args[i + 1]);
                    i++;
                }
                else if (args[i] == "-o")
                {
                    output = new StreamWriter(args[i + 1]);
                    i++;
                }
                else if (args[i] == "-d")
                {
                    step *= -1;
                }
                else if (args[i] == "-s")
                {
                    step *= int.Parse(args[i + 1]);
                    i++;
                }
            }
        }

        private static char CaesarCypherLower(char letter)
        {
            byte asciiValue = Encoding.ASCII.GetBytes(new char[] { letter })[0];
            byte asciiMin = Encoding.ASCII.GetBytes(new char[] { 'a' })[0];
            byte asciiMax = Encoding.ASCII.GetBytes(new char[] { 'z' })[0];
            return CaesarCypher(ref asciiValue, asciiMin, asciiMax);
        }

        private static char CaesarCypherUpper(char letter)
        {
            byte asciiValue = Encoding.ASCII.GetBytes(new char[] { letter })[0];
            byte asciiMin = Encoding.ASCII.GetBytes(new char[] { 'A' })[0];
            byte asciiMax = Encoding.ASCII.GetBytes(new char[] { 'Z' })[0];
            return CaesarCypher(ref asciiValue, asciiMin, asciiMax);
        }

        private static char CaesarCypherOther(char letter)
        {
            byte asciiValue = Encoding.ASCII.GetBytes(new char[] { letter })[0];
            byte asciiMin = Encoding.ASCII.GetBytes(new char[] { '!' })[0];
            byte asciiMax = Encoding.ASCII.GetBytes(new char[] { '@' })[0];
            //is encryptable symbol?
            if (asciiValue < asciiMin || asciiValue > asciiMax)
            {
                return letter;
            }
            return CaesarCypher(ref asciiValue, asciiMin, asciiMax);
        }

        private static char CaesarCypher(ref byte asciiValue, byte asciiMin, byte asciiMax)
        {
            asciiValue += (byte)step;
            //character overflow or underflow correction
            if (asciiValue < asciiMin)
            {
                asciiValue = (byte)(asciiMax - (asciiMin - asciiValue) + 1);
            }
            if (asciiValue > asciiMax)
            {
                asciiValue = (byte)(asciiMin + (asciiValue - asciiMax) - 1);
            }
            return Encoding.ASCII.GetChars(new byte[] { asciiValue })[0];
        }
    }
}