Why do I get an IndexOutOfRangeException Error when I wan't to enter the coordinates

Question

this is my code: `

using System;
using System.Linq;

namespace Schiffeversenken
{
    class Program
    {
        static void Main(string[] args)
        {
            // Größe der Karte
            const int width = 10;
            const int height = 10;

            // Die Karte als 2d Array von ints initialisieren
            int[,] grid = new int[width, height];

            // Schiffe platzieren (fünf Schiffe der Größe 1x1)
            for (int i = 0; i < 5; i++)
            {
                int x = new Random().Next(0, width);
                int y = new Random().Next(0, height);
                grid[x, y] = 1;
            }

            // Spiel loop
            while (true)
            {
// Karte anzeigen
                Console.WriteLine("    0 1 2 3 4 5 6 7 8 9");
                Console.WriteLine("   -------------------");
                for (int yCoord = 0; yCoord < height; yCoord++)
                {
                    Console.Write($" {yCoord} |");
                    for (int xCoord = 0; xCoord < width; xCoord++)
                    {
                        if (grid[xCoord, yCoord] == 0)
                        {
                            Console.Write(" ");
                        }
                        else if (grid[xCoord, yCoord] == 1)
                        {
                            Console.Write("X");
                        }
                        else if (grid[xCoord, yCoord] == 2)
                        {
                            Console.Write("O");
                        }
                        Console.Write("|");

                    }
                    Console.WriteLine();
                }
                Console.WriteLine("   -------------------");
                Console.WriteLine("     0 1 2 3 4 5 6 7 8 9");
                Console.WriteLine("    (X-Koordinate)");
                
                // Schiessen
                Console.WriteLine("Gib die Koordinaten für deinen Schuss ein (x y):");
                int[] input = Console.ReadLine()
                    .Split(' ')
                    .Select(s => int.Parse(s))
                    .ToArray();
                int x = input[0];
                int y = input[1];

// Prüfen, ob die Indizes innerhalb der Grenzen des Arrays liegen
                if (x >= 0 && x < width && y >= 0 && y < height)
                {
                    // Prüfen, ob ein Schiff getroffen wurde
                    if (grid[x, y] == 1)
                    {
                        Console.WriteLine("Treffer!");
                        grid[x, y] = 2;
                    }
                    else
                    {
                        Console.WriteLine("Daneben.");
                    }
                }
                else
                {
                    Console.WriteLine("Die Koordinaten liegen außerhalb des Spielfelds.");
                }


            }
        }
    }
}

Why do I get this IndexOutOfRangeException Error?

System.IndexOutOfRangeException: Index was outside the bounds of the array. at Schiffeversenken.Program.Main(String[] args) in C:\Users\timoa\RiderProjects\Battleships\Battleships\Program.cs:line 64

When I enter the coordinates?

I already tried to let it check if the indices are within the bounds of the array. That didn't worked.

Does the exception occur before or after the "Gib die Koordinaten" prompt is displayed? In the second case: What did you provide as input? — Klaus Gütter, Jan 03 '23 at 07:25
If you provide the right input (like `4 5`) it should work. Are you trying to enter one coordinate at a time? — Palle Due, Jan 03 '23 at 08:39

score 1 · Answer 1 · answered Jan 03 '23 at 07:31

Input validation is missing. If the user doesn't input something in the format x y then accessing the first or second part will lead to this exception.

            int x = input[0];
            int y = input[1];

should be

            int x,y;
            do
            {
                string[] input = Console.ReadLine()Split(' ');
            } while (!int.TryParse(input.ElementAtOrDefault(0), out x) || !int.TryParse(input.ElementAtOrDefault(1), out y))

Why do I get an IndexOutOfRangeException Error when I wan't to enter the coordinates

1 Answers1