C#中的QuickSort算法问题 [英] Problem with QuickSort algorithm in C#

问题描述

朋友，我用c#编写了一个快速排序算法，但是有一个问题，当我编译它时，它在某些情况下不起作用.例如，当我在textbox6中输入数字12、32、11进行排序时，它给出了超出范围的错误.当我去追踪它时，调试器显示num []取了nums [0] = 12，nums [1] = 11，nums [2] = 1我在问题中做了评论，在此先感谢

已编辑:我更改了while条件，但现在不会出现超出范围的错误，但是当输入为12,32,11时输出11,12,1

Hi friends, I wrote a quicksort algorithm in c# but it has a problem,when I compile it, it doesn''t work in some conditions. For example when I enter number 12, 32, 11 in textbox6 to sort, it gives out of range error. When I go to trace it, debugger shows that num[] took nums[0]=12, nums[1]=11, nums[2]=1 I commented in the lines of problem, thanks in advance

Edited: I changed the while condition and it now doesn''t give out of range error but when the input is 12,32,11 output 11,12,1

private void button5_Click(object sender, EventArgs e)
    {
        string[] x = textBox6.Text.Split(',');
        int[] nums = new int[x.Length];
    
        for (int counter = 0; counter < x.Length; counter++)
        {
            nums[counter] = Convert.ToInt32(x[counter]);
        }
        int i = 0;
        int  j = nums.Length;
        int pivot = nums[0];
        do
        {
            do
            {
                    i++;
            }
                while ((i < nums.Length) && (nums[i] < pivot));

            do
                {
                    j--;
                }
while (nums[j]>pivot);
            if (i < j)
            {
                int temp = i;
                nums[i] = nums[j];
                nums[j] = temp;
            }
        }while(i<j);
        int temp1 = nums[0];
        nums[0] = nums[j];
        nums[j] = temp1;
        int pivotpoint = j;
        string QuickSort = "";
        foreach (var n in nums)
           QuickSort += n.ToString() + ",";
        textBox5.Text = QuickSort;
    }

推荐答案

是的，它会的.
因为您要在循环保护中检查的全部是"nums [i] ＜pivot"，如果第一个元素在组中最大，则循环将总是用完元素.您必须选中"i< nums.Length"或"i< j"

Yes, it will do.
Because all you check for in the loop guard is "nums[i] < pivot" if the first element is the largest in the group the loop will always run out of elements. You must include a check for "i < nums.Length" or "i < j"

阿鲁什，

读取int temp = i;
的行 应该最可能读为int temp = num[i];
因为i和j是索引，而您要使用
完成 名为temp的变量是将数组元素num [i]与num [j]交换.
这就是我在您的代码中看到的问题.


问候，

曼弗雷德(Manfred)

Hi Arash,

the line that reads int temp = i;
should most probably read like int temp = num[i];
because i and j are indexes and what you''re trying to accomplish with
the variable named temp is swapping of the array element num[i] with num[j].
That''s the problem I see with your code.


Regards,

Manfred

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