This document describes a C# program that implements a phone book. The program reads in a file with names and phone numbers and builds a phone book data structure from that file. It then allows the user to search the phone book by name and returns the corresponding phone number. The document includes the source code for the program and shows sample output demonstrating it successfully searching for names and returning phone numbers or indicating when a name is not found.

1. This C# Program Implements PhoneBook.Reads a file with names and phone numbers
and builds a phone book from it and Returns the phone number for a given name.
Here is source code to Implement PhoneBook.The C# program is successfully
compiled and executed with Microsoft Visual Studio. The program output is also
shown below.
/*
* C# Program to Implement PhoneBook
*/
using System;
using System.Collections;
using System.IO;
class PhoneBook
{
static void Main(string[] arg)
{
Hashtable tab = new Hashtable();
string fileName;
if
{
(arg.Length > 0) fileName = arg[0];
}
else
{
fileName = "phoneBook.txt";
}
StreamReader r = File.OpenText(fileName);
string line = r.ReadLine();
while (line != null)
{
int pos = line.IndexOf('=');
string name = line.Substring(0, pos).Trim();
long phone = Convert.ToInt64(line.Substring(pos + 1));
tab[name] = phone;
line = r.ReadLine();
}
r.Close();
for (; ; )
{
Console.Write("Name : ");
string name = Console.ReadLine().Trim();
if (name == "")
break;
object phone = tab[name];
if (phone == null)
Console.WriteLine("-- Not Found in Phone Book");
else
Console.WriteLine(phone);
}
}
}
Here is the output of the C# Program:
Name : Ram
9999945670
Name : Raj
-- Not Found in Phone Book