HTDS: Wrapping at End of Fixed Character String

caesar-cipher.cs

using System;
using System.Text;

namespace CesarCipher {
  class Program {
    static void Main(string[] args) {

      // if upper or lower letter increment by N (rotate at end of alphabet) 
      // 97 - 122 lower, 65 - 90 upper
      // % 26 allows us to work with #'s greater than 26 with same algorithm
      var offset = 2 % 26;
      var input = "Yes";
      var output = new StringBuilder();

      foreach (var character in input) {
        if (char.IsLower(character)) {
          output.Append((char)(97 + ((character - 97) + offset) % 26));
        } else if (char.IsUpper(character)) {
          output.Append((char)(65 + ((character - 65) + offset) % 26));
        } else {
          output.Append(character);
        }
      }

      Console.WriteLine(output);  // Agu
    }
  }
}