adding values to an array in a method every time you call the method

Question

I have an array called passengers , lets say it has 10 places. I also have a class for new passenger which gonna have the age of the passenger. I want to add a new passenger to the array by his age. This passenger is gonna be created by its class through calling the constructor. Lets say I add only ONE passenger by calling the method and 9 places are EMPTY. The NEXT time a call the method, I want to add a new passenger in the next place in the passengers array, So every time I want to add a new passenger, i call the passenger method, and it will be saved in the next empty place in array. until it is full. A message will say it is full and no passenger can go on.

My problem with my code is that i have to enter all passengers at once. but i want to enter only one passenger every time I call the method.

public void Add_Passengers ()
    {
        Console.WriteLine("How old are the passengers?");

        for (int i = 0; i < passengers.Length; i++)
        {
            int age = Int32.Parse(Console.ReadLine());
            passengers[i] = new Passenger(age);
        }
    }

Answer 1

    /// <summary>
    /// Passengers array
    /// </summary>
    public Passenger[] Passengers = new Passenger[10];

    public class Passenger
    {
        public int Age { get; set; }

        public Passenger(int age)
        {
            Age = age;
        }
    }

    public void AddPassenger()
    {
        // Get the number of passengers
        int passengerCount = Passengers.Count(p => p != null);

        if (passengerCount == Passengers.Length)
            Console.WriteLine("Maximum number of passengers");
        else
        {
            Console.WriteLine("How old are the passengers?");
            int age = int.Parse(Console.ReadLine());

            // Add passenger
            Passengers[passengerCount] = new Passenger(age);
        }
    }

Answer 2

You can try:

    public void AddPassengers(Passenger[] passengers)
    {
        int i = Array.IndexOf(passengers, null);

        if (i < 0)
        {
            Console.WriteLine("The array is full.");
            return;
        }

        Console.WriteLine("How old is the passenger?");

        int age = Int32.Parse(Console.ReadLine());
        passengers[i] = new Passenger(age);
    }

Hope this helps.

Answer 3

public void Add_Passengers()
    {
        PassengerClass PassengerClass = new PassengerClass();

        Console.WriteLine("How old are the passengers?");

        PassengerClass.AddPassanger(Int32.Parse(Console.ReadLine()));
    }

    public class PassengerClass
    {
        public List<int> passangerList;
        public PassengerClass()
        {
            if (passangerList == null)
                passangerList = new List<int>();
        }

        public void AddPassanger(int age)
        {
            passangerList.Add(age);
        }
    }

Answer 4

I would go with the class solution:

public class Passanger {
        public int age;

        public Passanger(int age)
        {
            this.age = age;
        }
    }

    public class Passangers
    {
        private List<Passanger> passangers;
        private int limit;
        public bool ready { get; private set; }

        public Passangers(int capacity)
        {
            passangers = new List<Passanger>(capacity);
            limit = capacity;
            ready = false;
        }

        public void addPassanger(Passanger passanger)
        {
            passangers.Add(passanger);

            if(passangers.Count == limit)
            {
                ready = true;
            }
        }

        public List<Passanger> getPassangers()
        {
            passangers.Sort((p1, p2) => p1.age.CompareTo(p2.age));
            return passangers;
        }
    }

Answer 5

Rather than iterating the array each time, you can keep an additional field tracking the index and increment it within the add operation.

private Passenger[] passengers = new Passenger[10];
private int _count = 0;
public void Add_Passengers()
{
    // validate overflow. >= not strictly necessary but a better safeguard than ==
    if (_count >= passengers.Length)
       throw new InvalidOperationException("Array is filled");
    
    Console.WriteLine("How old are the passengers?");
    
    // validate input
    if (!int.TryParse(Console.ReadLine(), out int age)) 
      throw new InvalidOperationException("Not an integer");

    // Postfix increment returns original value 
    passengers[_count++] = new Passenger(age);
    
}

Obviously you should handle the error cases as you see fit. For demonstration I'm simply throwing an InvalidOperationException .

Edit: I just noticed you asked explicitly to display an Error message. That could look like this:

private Passenger[] passengers = new Passenger[10];
private int _count = 0;
public void Add_Passengers()
{
    // validate overflow. >= not strictly necessary but a better safeguard than ==
    if (_count >= passengers.Length)
    {
       Console.WriteLine("Error: No more passengers are allowed. Size limit reached.");
       return;
    } 
    
    Console.WriteLine("How old are the passengers?");
    
    // validate input
    if (!int.TryParse(Console.ReadLine(), out int age)) 
    {
       Console.WriteLine("Error: Value is not an integer");
       return;
    } 

    // Postfix increment returns original value 
    passengers[_count++] = new Passenger(age);
    
}

A List<Passenger> is probably a better option. Then you don't need to track the index or worry about the size overflowing. Note that neither solution is thread-safe, but that's a different question.