C# Booking Project

Your brief

Create one session with a validated capacity and a Reserve operation. A request must be positive and fit the remaining places. Rejection must not alter the previously accepted reservations. Keep the remaining-space check before mutation so overflow cannot create a misleading successful count. The type is a small single-process teaching object, not a multi-user booking service. A real service also needs authentication, persistent transactions, duplicate-request handling and concurrency control at the shared storage boundary.

Run it locally

Use the .NET 10 SDK with C# 14 in a separate console lab. Create an empty project once with dotnet new console --framework net10.0, then replace Program.cs with this complete source and add any supporting files shown. Keep only one lesson entry point in the project. C# does not currently run in Bhylu’s browser playground. Apache, PHP and MySQL are not needed.

dotnet build -p:LangVersion=14.0 -p:Nullable=enable -p:TreatWarningsAsErrors=true
dotnet run --no-build

Use the SDK’s project workflow; the review compiles against its matching reference assemblies and executes the results without external NuGet packages. File-writing examples belong in a private empty lab directory.

Download the complete C# source as Program.cs.

Worked solution

using System;

internal static class Program
{
    private static void Main(string[] args)
    {
        var session = new BookingSession(8);
        Console.WriteLine($"First: {session.Reserve(5)}");
        Console.WriteLine($"Excess: {session.Reserve(4)}");
        Console.WriteLine($"Exact: {session.Reserve(3)}");
        Console.WriteLine($"Reserved: {session.Reserved}");
    }
}

internal sealed class BookingSession
{
    public int Capacity { get; }
    public int Reserved { get; private set; }
    public BookingSession(int capacity)
    {
        if (capacity is < 1 or > 1000) throw new ArgumentOutOfRangeException(nameof(capacity));
        Capacity = capacity;
    }
    public bool Reserve(int requested)
    {
        if (requested < 1 || requested > Capacity - Reserved) return false;
        Reserved += requested; return true;
    }
}

First: True
Excess: False
Exact: True
Reserved: 8

Extend and test

Test zero, negative requests, exact remaining capacity, a request one too large, repeated calls after full capacity and invalid construction. Check unchanged state after every false return.