Question

I want choice == 1 to only be able to be selected five times, so I initialized a variable firstClass = 0, then set up a do-while for firstClass < 5. I included firstClass++ in my do-while to act as a counter. However, I think firstClass is re-initializing every time I call the method CheckIn(). How can I prevent this from happening? Thanks in advance.

using System;

namespace Assignment7
{
    class Plane
    {
        public static void Main(string[] args)
        {
            Console.WriteLine("Welcome to the Airline Reservation System.");
            Console.WriteLine("Where would you like to sit?\n");
            Console.WriteLine("Enter 1 for First Class.");
            Console.WriteLine("Enter 2 for Economy.");
            CheckIn();
        }

        public static void CheckIn()
        {
            int choice = Convert.ToInt32(Console.ReadLine());
            int firstClass = 0;
            int economy = 0;

            if (choice == 1)
            {
                do
                {
                    Console.WriteLine("You have chosen a First Class seat.");
                    firstClass++;
                    CheckIn();
                } while (firstClass < 5);
            }
            else if (choice == 2)
            {
                do
                {
                    Console.WriteLine("You have chosen an Economy seat.");
                    economy++;
                    CheckIn();
                } while (economy < 5);
            }
            else
            {
                Console.WriteLine("That does not compute.");
                CheckIn();
            }
        }
    }
}

Answer 1

That is entirely normal. If you want the variable to exist outside the method, you must declare it outside a method, as a “field”. Simply move the:

int firstClass = 0;

outside the method, adding the static modifier (in this case):

static int firstClass = 0;

Note also that this by itself is not thread-safe; if threading is an issue (for example, ASP.NET) then use int newValue = Interlocked.Increment(ref firstClass);. I only mention this because in the general case static data should consider threading, but I suspect it isn’t an issue in your case (a console exe).