A Contact Management System is a practical project that demonstrates core C# programming concepts including collections, LINQ, object-oriented principles and data management. This console application allows users to add, view, search, update, and delete contacts.
Functionalities Overview
The Contact Management System provides functionality to:
- Add new contacts with details (name, phone, email, address)
- View all contacts in a formatted display
- Search contacts by name or phone number
- Update existing contact information
- Delete contacts from the system
- Sort contacts alphabetically
Steps to Implement
Step 1: Initialize empty contact list using List<T>
Step 2: Display menu options to user
Step 3: Process user choice:
- Add: Create new contact object and add to list
- View: Display all contacts using LINQ ordering
- Search: Filter contacts using LINQ queries
- Update: Find contact and modify properties
- Delete: Remove contact from collection
Step 4: Continue until user chooses to exit
Program Implementation
using System;
using System.Collections.Generic;
using System.Linq;
namespace ContactManagement
{
class Contact
{
public int Id { get; set; }
public string Name { get; set; }
public string Phone { get; set; }
public string Email { get; set; }
public string Address { get; set; }
public override string ToString() => $"[{Id}] {Name} | {Phone} | {Email} | {Address}";
}
class Program
{
static List<Contact> contacts = new List<Contact> {
new Contact { Id = 1, Name = "John Doe", Phone = "555-0123", Email = "john@email.com", Address = "123 Main St" },
new Contact { Id = 2, Name = "Jane Smith", Phone = "555-0456", Email = "jane@email.com", Address = "456 Oak Ave" }
};
static int nextId = 3;
static void Main(string[] args)
{
Console.WriteLine("=== Contact Management System ===");
var actions = new Dictionary<string, Action> {
{"1", AddContact}, {"2", ViewAllContacts}, {"3", SearchContact},
{"4", UpdateContact}, {"5", DeleteContact}
};
while (true)
{
Console.WriteLine("\n1. Add Contact\n2. View All Contacts\n3. Search Contact");
Console.WriteLine("4. Update Contact\n5. Delete Contact\n6. Exit");
Console.Write("Choose option: ");
string choice = Console.ReadLine();
if (choice == "6") { Console.WriteLine("Goodbye!"); break; }
if (actions.ContainsKey(choice)) actions[choice]();
else Console.WriteLine("Invalid option!");
}
}
static void AddContact()
{
string GetInput(string prompt) { Console.Write(prompt); return Console.ReadLine(); }
contacts.Add(new Contact {
Id = nextId++,
Name = GetInput("Enter name: "),
Phone = GetInput("Enter phone: "),
Email = GetInput("Enter email: "),
Address = GetInput("Enter address: ")
});
Console.WriteLine("Contact added successfully!");
}
static void ViewAllContacts()
{
if (!contacts.Any()) { Console.WriteLine("No contacts found!"); return; }
Console.WriteLine("\n--- All Contacts ---");
contacts.OrderBy(c => c.Name).ToList().ForEach(Console.WriteLine);
}
static void SearchContact()
{
Console.Write("Enter search term (name/phone): ");
string term = Console.ReadLine()?.ToLower();
var results = contacts.Where(c => c.Name.ToLower().Contains(term) || c.Phone.Contains(term)).ToList();
Console.WriteLine(results.Count == 0 ? "No contacts found!" : $"\nFound {results.Count} contact(s):");
results.ForEach(Console.WriteLine);
}
static void UpdateContact()
{
Console.Write("Enter contact ID to update: ");
if (!int.TryParse(Console.ReadLine(), out int id)) { Console.WriteLine("Invalid ID!"); return; }
var contact = contacts.FirstOrDefault(c => c.Id == id);
if (contact == null) { Console.WriteLine("Contact not found!"); return; }
Console.WriteLine($"Updating: {contact}\nPress Enter to keep current value");
string UpdateField(string field, string current) {
Console.Write($"{field} [{current}]: ");
string input = Console.ReadLine();
return string.IsNullOrEmpty(input) ? current : input;
}
contact.Name = UpdateField("Name", contact.Name);
contact.Phone = UpdateField("Phone", contact.Phone);
contact.Email = UpdateField("Email", contact.Email);
contact.Address = UpdateField("Address", contact.Address);
Console.WriteLine("Contact updated!");
}
static void DeleteContact()
{
Console.Write("Enter contact ID to delete: ");
if (!int.TryParse(Console.ReadLine(), out int id)) { Console.WriteLine("Invalid ID!"); return; }
var contact = contacts.SingleOrDefault(c => c.Id == id);
if (contact == null) { Console.WriteLine("Contact not found!"); return; }
Console.WriteLine($"Deleting: {contact}");
Console.Write("Are you sure? (y/n): ");
if (Console.ReadLine()?.ToLower() == "y") {
contacts.Remove(contact);
Console.WriteLine("Contact deleted!");
} else Console.WriteLine("Deletion cancelled.");
}
}
}
Outputs
1: View All Contacts (after initialization)
Initial state: Contacts list has 2 entries: John Doe, Jane Smith.
Steps:
- Program starts: sample contacts are added.
- User chooses option
2(View All Contacts). - LINQ orderby sorts contacts by Name.
Output:
2: Add Contact
Initial state:
- Contacts: John Doe (Id=1), Jane Smith (Id=2).
- nextId = 3.
Steps:
- User chooses option 1 (Add Contact).
- Enter details.
- Program creates a new Contact with Id = 3 and adds it.
Output:
3. Search Contact
Initial state:
- Contacts: John Doe (1), Jane Smith (2), Alice Brown (3).
Steps:
- User chooses option 3 (Search Contact).
- Enters search term: jane.
- LINQ .Where() finds matches in Name or Phone.
Output:
4: Update Contact
Initial state:
- Contacts: John Doe (1), Jane Smith (2), Alice Brown (3).
Steps:
- User chooses option 4 (Update Contact).
- Enters contact ID: 1.
- Program loads John Doe.
- User enters new phone and skips others (presses Enter):
- John Doe’s phone is updated.
Output:
5: Delete Contact
Initial state:
- Contacts: John Doe (1), Jane Smith (2), Alice Brown (3).
Steps:
- User chooses option 5 (Delete Contact).
- Enters ID: 2.
- Program loads Jane Smith and asks for confirmation
- Contact removed from list.
Output:
