int x = 5; // x is a local variable and is stored on the stack

// y is a reference to an object and is stored on the stack
// the object itself is stored on the heap
string y = new string("hello");

// z is a reference to the same object as y
// both y and z are stored on the stack, but the object is only stored once on the heap
string z = y;

// the object referenced by y and z is no longer needed, so the garbage collector will deallocate the memory on the heap
y = null;
z = null;

int x = 5; // x is a local variable and is stored on the stack

// y is a reference to an object and is stored on the stack
// the object itself is stored on the heap
string y = new string("hello");

// z is a reference to the same object as y
// both y and z are stored on the stack, but the object is only stored once on the heap
string z = y;

// the object referenced by y and z is no longer needed, so the garbage collector will deallocate the memory on the heap
y = null;
z = null;

Car myCar = new ();
Car newCar = myCar; // references the same memory as myCar
newCar.IsRunning = true // myCar and newCar's .IsRunning property change to true
newCar = null // or if set to a new object, only newCar changes but not the myCar object

Car myCar = new ();
Car newCar = myCar; // references the same memory as myCar
newCar.IsRunning = true // myCar and newCar's .IsRunning property change to true
newCar = null // or if set to a new object, only newCar changes but not the myCar object

[HttpPost]
[Authorize]
public async Task<IActionResult> TrainingSessionRosterReview(int id, TrainingSessionRosterReview model, CancellationToken cancellationToken = default)
{
    List<CourseSessionRegistration> courseSessionRegistrations = await this.DbContext.CourseSessionRegistrations.Where(x => x.CourseSessionId == id).ToListAsync(cancellationToken);

    foreach (CourseSessionRegistration courseSessionRegistration in courseSessionRegistrations)
    {
        TrainingSessionRosterRegistrant? currentRegistrant = model.Registrants.FirstOrDefault(reg => reg.RegistrantId == courseSessionRegistration.RegistrantId);

        if (currentRegistrant != null)
        {
            courseSessionRegistration.Attended = currentRegistrant.IsAttendanceConfirmed;
            courseSessionRegistration.AttendanceConfirmationDate = currentRegistrant.IsAttendanceConfirmed ? DateTime.Now : null;
        }
    }

    await this.DbContext.SaveChangesAsync(cancellationToken);

    return this.RedirectToAction(nameof(AdminController.TrainingSessionRoster));
}

[HttpPost]
[Authorize]
public async Task<IActionResult> TrainingSessionRosterReview(int id, TrainingSessionRosterReview model, CancellationToken cancellationToken = default)
{
    List<CourseSessionRegistration> courseSessionRegistrations = await this.DbContext.CourseSessionRegistrations.Where(x => x.CourseSessionId == id).ToListAsync(cancellationToken);

    foreach (CourseSessionRegistration courseSessionRegistration in courseSessionRegistrations)
    {
        TrainingSessionRosterRegistrant? currentRegistrant = model.Registrants.FirstOrDefault(reg => reg.RegistrantId == courseSessionRegistration.RegistrantId);

        if (currentRegistrant != null)
        {
            courseSessionRegistration.Attended = currentRegistrant.IsAttendanceConfirmed;
            courseSessionRegistration.AttendanceConfirmationDate = currentRegistrant.IsAttendanceConfirmed ? DateTime.Now : null;
        }
    }

    await this.DbContext.SaveChangesAsync(cancellationToken);

    return this.RedirectToAction(nameof(AdminController.TrainingSessionRoster));
}