The base Keyword in C#: Constructors, Methods, and Fields—Ticketing Example

Inheritance is about building on top of a foundation. In C#, the base keyword is how a derived (child) class reuses, extends, or clarifies behavior defined in its base (parent) class.

This post delivers a practical, end-to-end understanding of base in three places you’ll use it most:

1. Call the base class constructor

2. Access (and extend) base class methods

3. Access base class properties and fields

In a ticketing system, you may have multiple layers of tickets:

• Base Ticket: The fundamental ticket with an ID and issue date.

• Event Ticket: Adds event name and seat info.

• VIP Ticket: Extends further with perks like lounge access or free snacks.

Step 1: Calling the Base Constructor

Every ticket must have a TicketId and IssueDate. That’s our base.

public class Ticket
{
    public string TicketId { get; }
    protected DateTime IssueDate { get; }

    public Ticket(string ticketId)
    {
        TicketId = ticketId;
        IssueDate = DateTime.UtcNow;
        Console.WriteLine($"[Ticket] Issued Ticket #{TicketId} on {IssueDate:d}");
    }

    public virtual void PrintDetails()
    {
        Console.WriteLine($"Ticket #{TicketId}, Issued: {IssueDate:d}");
    }
}

Now, when we create an EventTicket, it should still initialize as a Ticket first.
👉 That’s where : base(ticketId) comes in.

public class EventTicket : Ticket
{
    public string EventName { get; }
    public string SeatNumber { get; }

    public EventTicket(string ticketId, string eventName, string seatNumber)
        : base(ticketId) // ✅ call base constructor
    {
        EventName = eventName;
        SeatNumber = seatNumber;
        Console.WriteLine($"[EventTicket] Event: {EventName}, Seat: {SeatNumber}");
    }
}

Usage

https://medium.com/@dotnetfullstackdev

var basic = new EventTicket("T1001", "Jazz Night", "A12");

Output

[Ticket] Issued Ticket #T1001 on 9/7/2025
[EventTicket] Event: Jazz Night, Seat: A12

👉 Transition: A ticket is always born as a basic ticket first, then becomes specialized.

Step 2: Accessing and Extending Base Methods

The base ticket can print its details. But the event ticket wants to add event info.

public class EventTicket : Ticket
{
    public string EventName { get; }
    public string SeatNumber { get; }

    public EventTicket(string ticketId, string eventName, string seatNumber)
        : base(ticketId)
    {
        EventName = eventName;
        SeatNumber = seatNumber;
    }

    public override void PrintDetails()
    {
        base.PrintDetails(); // ✅ reuse base printing
        Console.WriteLine($"Event: {EventName}, Seat: {SeatNumber}");
    }
}

Usage

basic.PrintDetails();

Output

Ticket #T1001, Issued: 9/7/2025
Event: Jazz Night, Seat: A12

Transition: We didn’t throw away the parent’s printing logic — we extended it with event data.

Step 3: Accessing Base Properties and Fields

Now we add a VIP Ticket. It still has event details, but also perks.

Notice that the base ticket had a protected IssueDate. We can access it in derived classes to enrich the output.

public class VipTicket : EventTicket
{
    public string Perks { get; }

    public VipTicket(string ticketId, string eventName, string seatNumber, string perks)
        : base(ticketId, eventName, seatNumber) // ✅ base constructor
    {
        Perks = perks;
    }

    public override void PrintDetails()
    {
        base.PrintDetails(); // ✅ call parent details
        Console.WriteLine($"VIP Perks: {Perks}");
        Console.WriteLine($"(Issued originally on {IssueDate:d})"); // ✅ base field
    }
}

Usage

var vip = new VipTicket("T2001", "Rock Concert", "B5", "Lounge + Free Drinks");
vip.PrintDetails();

Output

Ticket #T2001, Issued: 9/7/2025
Event: Rock Concert, Seat: B5
VIP Perks: Lounge + Free Drinks
(Issued originally on 9/7/2025)

Transition: The VIP ticket doesn’t reinvent — it inherits everything, calls base, and adds perks.

Recap

We’ve seen base evolve naturally in a Ticketing System:

1. Call base constructor → A ticket always starts as a Ticket before being an Event or VIP ticket.

2. Access and extend methods → Event and VIP tickets reuse PrintDetails() before adding their own info.

3. Access base properties/fields → VIP ticket can display the inherited IssueDate.

Key Takeaway

The base keyword is your bridge to the parent class:

• Ensures core initialization (constructor).

• Preserves parent functionality (methods).

• Grants access to inherited state (fields/properties).

Think of it like a ticketing upgrade path:

• Every ticket starts as a base ticket.

• You reuse the core details.

• You extend it into richer experiences (event seating, VIP perks).

That’s base in action — layered, reusable, and consistent.