Codecademy export

Program.cs

using System;
using System.Linq;

namespace CaesarCipher
{
  class Program
  {
    static void Main(string[] args)
    {
      char[] alphabet = new char[] {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
      Console.WriteLine("Please, enter a message: ");
      char[] secretMessage = Console.ReadLine().ToCharArray();
      char[] encryptedMessage = new char[secretMessage.Length];
      int index = 0;
      foreach(char character in secretMessage) {
        encryptedMessage[index ++] = alphabet.Contains(character) ? alphabet[(Array.IndexOf(alphabet, character) + 3) % alphabet.Length] : character;
      }
      Console.WriteLine(String.Join("", encryptedMessage)); 
    }
  }
}