Question

At runtime the program says an index is out of range, but I don’t know why.

The line that the error messager points out is

Points[counter + ((int)(radius * 100))].X = i;

If that one has an error, the next one (with the same index) must also have an error.

Points[counter + ((int)(radius * 100))].Y = (Points[counter].Y * -1);

Here is the code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            Circle circle = new Circle(new Point2D(30F, 30F), 10F);
            foreach (Point2D point in circle.Points)
            {
                Console.Write(point.X + " = X\n" + point.Y + " = Y");
                Console.ReadKey();
            }
        }
    }

    public struct Point2D
    {
        public float X;
        public float Y;

        public Point2D(float x, float y)
        {
            this.X = x;
            this.Y = y;
        }
    }

    class Circle
    {
        public Point2D[] Points;
        float h, k;
        float radiusStart, radiusEnd;
        int counter;

        public Circle(Point2D location, float radius)
        {
            Points = new Point2D[(int)(radius * 201)];
            h = location.X;
            k = location.Y;
            radiusStart = h - radius;
            radiusEnd = h + radius;

            for (float i = radiusStart; i <= radiusEnd; i++)
            {
                Points[counter].X = i;
                Points[counter].Y = (float)(Math.Sqrt((radius * radius) - ((i - h) * (i - h))) + k);
                Points[counter + ((int)(radius * 100))].X = i;
                Points[counter + ((int)(radius * 100))].Y = (Points[counter].Y * -1);
                counter++;
            }

            counter = 0;
        }
    }
}

Thank you in advance

Adrian Collado

Answer 1

I’ve seen bizarre behavior with: i = i++

Try changing for (float i = radiusStart; i <= radiusEnd; i = i++) to just use i++ instead of i = i++.

Even if it doesn’t fix your issue, it’s much better form.