C# IndexOutOfRangeException 异常

Question

程序在运行时说索引超出范围，但我不知道为什么。

错误信息指出的行是

点[计数器 + ((int)(radius * 100))].X = i;

如果那个有错误，下一个(具有相同索引)也一定有错误。

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

代码如下:

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;
        }
    }
}

提前致谢

阿德里安科拉多

Answer 1

问题出在 for 循环的递增步骤中:i = i++。它应该只是 i++ 或 ++i。

i++ 递增 i 并返回其先前的值，然后您再次将其分配回 i。因此，i 实际上在循环的每次迭代中都以相同的值结束，因此它永远不会大于 radiusEnd，并且循环永远不会终止(直到计数器超过数组的上限并且您得到超出范围的异常)。