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C# - Phonebook Program

Learn, how to create / design a phonebook application using C# program?
Submitted by Nidhi, on August 20, 2020 [Last updated : March 22, 2023]

Creating a phonebook application

Here, we will create a C# program to create a phonebook using HashTable, here we add numbers to the Phonebook and get numbers from the phone book.

C# program to implement phonebook

The source code to create a phonebook in C# is given below. The given program is compiled and executed successfully on Microsoft Visual Studio.

//Program to implement phonebook in C#.
using System;
using System.Collections;
class program {
  public static void Main() {
    Hashtable phoneBook = new Hashtable();

    while (true) {
      Console.WriteLine("\n#############PhoneBook###########");
      Console.WriteLine("\t1:Add number to phone book");
      Console.WriteLine("\t2:Get number to phone book");
      Console.WriteLine("\t3:Exit");
      Console.WriteLine("\n#################################");
      Console.WriteLine("\n\nEnter choice: ");
      int choice = Convert.ToInt32(Console.ReadLine());

      switch (choice) {
      case 1:
        {
          long number = 0;
          string name = "";

          Console.Write("Enter your name : ");
          name = Console.ReadLine();

          Console.Write("Enter your phone number : ");
          number = Convert.ToInt64(Console.ReadLine());

          phoneBook.Add(name, number);
        }
        break;
      case 2:
        {
          long number = 0;
          string name = "";

          Console.Write("Enter your name : ");
          name = Console.ReadLine();

          if (phoneBook[name] == null) {
            Console.WriteLine("Given name is not found in phonebook");
          }
          else {
            number = Convert.ToInt64(phoneBook[name]);
            Console.WriteLine("Name: " + name + ", phone number: " + number);
          }
        }
        break;
      case 3:
        {
          goto OUT;
        }
        break;
      default:
        {
          Console.WriteLine("\nYou have entered wrong choice");
        }
        break;
      }
    }

    OUT:
    Console.WriteLine("\nThankyou for using phonebook");
  }
}

Output

#############PhoneBook###########
        1:Add number to phone book
        2:Get number to phone book
        3:Exit
#################################


Enter choice:
1
Enter your name : Arvind
Enter your phone number : 8860572892

#############PhoneBook###########
        1:Add number to phone book
        2:Get number to phone book
        3:Exit
#################################

Enter choice:
2
Enter your name : Arvind
Name: Arvind, phone number: 8860572892

#############PhoneBook###########
        1:Add number to phone book
        2:Get number to phone book
        3:Exit
#################################

Enter choice:
3

Thankyou for using phonebook
Press any key to continue . . .

Explanation

In the above program, we created a phonebook using HashTable. Here we provide two options 1^st to add name and phone number to the phone book and 2^nd option is used to getting numbers from the phonebook.

As we know that we can store items in the hash table in the form key/value pair. Here we used the name as a key and phone number as the value in the phonebook hash table.

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