Using interface 3 : Interface : Class Interface C# Source Code

    

/*
C#: The Complete Reference 
by Herbert Schildt 

Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
using System; 

// An encryption interface. 
public interface ICipher { 
  string encode(string str); 
  string decode(string str); 
}

/* A simple implementation of ICipher that codes 
   a message by shifting each character 1 position 
   higher.  Thus, A becomes B, and so on. */ 
class SimpleCipher : ICipher { 
     
  // Return an encoded string given plaintext. 
  public string encode(string str) { 
    string ciphertext = ""; 
 
    for(int i=0; i < str.Length; i++) 
      ciphertext = ciphertext + (char) (str[i] + 1); 
 
    return ciphertext; 
  } 
 
  // Return an decoded string given ciphertext. 
  public string decode(string str) { 
    string plaintext = ""; 
 
    for(int i=0; i < str.Length; i++) 
      plaintext = plaintext + (char) (str[i] - 1); 
 
    return plaintext; 
  } 
} 
 
/* This implementation of ICipher uses bit 
   manipulations and key. */ 
class BitCipher : ICipher { 
  ushort key; 
 
  // Specify a key when constructing BitCiphers. 
  public BitCipher(ushort k) { 
    key = k; 
  } 
     
  // Return an encoded string given plaintext. 
  public string encode(string str) { 
    string ciphertext = ""; 
 
    for(int i=0; i < str.Length; i++) 
      ciphertext = ciphertext + (char) (str[i] ^ key); 
 
    return ciphertext; 
  } 
 
  // Return an decoded string given ciphertext. 
  public string decode(string str) { 
    string plaintext = ""; 
 
    for(int i=0; i < str.Length; i++) 
      plaintext = plaintext + (char) (str[i] ^ key); 
 
    return plaintext; 
  } 
}

// Use ICipher. 
 
// A class for storing unlisted telephone numbers. 
class UnlistedPhone { 
  string pri_name;   // supports name property 
  string pri_number; // supports number property 
 
  ICipher crypt; // reference to encryption object 
 
  public UnlistedPhone(string name, string number, ICipher c) 
  { 
    crypt = c; // store encryption object 
 
    pri_name = crypt.encode(name); 
    pri_number = crypt.encode(number); 
  } 
 
  public string Name { 
    get { 
      return crypt.decode(pri_name); 
    } 
    set { 
      pri_name = crypt.encode(value); 
    } 
  } 
 
  public string Number { 
    get { 
      return crypt.decode(pri_number); 
    } 
    set { 
      pri_number = crypt.encode(value); 
    } 
  } 
} 
 
// Demonstrate UnlistedPhone 
public class UnlistedDemo { 
  public static void Main() { 
    UnlistedPhone phone1 = 
        new UnlistedPhone("Tom", "555-3456", new BitCipher(27));  
    UnlistedPhone phone2 = 
        new UnlistedPhone("Mary", "555-8891", new BitCipher(9)); 
 
 
    Console.WriteLine("Unlisted number for " +  
                      phone1.Name + " is " + 
                      phone1.Number);  
 
    Console.WriteLine("Unlisted number for " +  
                      phone2.Name + " is " + 
                      phone2.Number);  
  } 
}