c# - 从数组中选择名称，在 listBox1 中打印所选名称并在 listBox2 中剩余

Question

我有这个错误：索引超出范围。必须是非负数且小于集合的大小。

我花了很长时间试图解决它，但我无法解决。请我需要帮助

public partial class Form1 : Form
    {
        string[] generate = new string[] {"Name1","Name2","Name3","Name4","Name5","Name6","Name7","Name8","Name9","Name10","Name11","Name12","Name13","Name14","Name15","Name16","Name17","Name18","Name19","Name20" };
        string[] n = new string[] { "Name1", "Name2", "Name3", "Name4", "Name5", "Name6", "Name7", "Name8", "Name9", "Name10", "Name11", "Name12", "Name13", "Name14", "Name15", "Name16", "Name17", "Name18", "Name19", "Name20" };
        String[] a = new String[20];
        string name;
        int Num;

        public Form1()
        {
            InitializeComponent();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e) // START btn
        {
            Num = int.Parse(textBox1.Text);
            if (Num < 20)
            {
                if (generate.Length >= Num)
                {
                    for (int i = Num; i > 0; i--)
                    {

                        name = generate.ElementAt(i);
                        listBox1.Items.Add(name); // Print it to list1 
                        generate = generate.Where(s => s != name).ToArray(); // Delete name after using
                    }
                }
                else MessageBox.Show("Sorry, remaining names =" + generate.Length);
                listBox2.Items.Clear();
                listBox2.Items.AddRange(generate);

            }
            else MessageBox.Show("Max name is 20!");

        }

Answer 1

问题是 20 个元素数组中的索引从 0 到 19。在您的代码中，您允许 20，这会出错

if (generate.Length >= Num)

你应该删除=标志。此外，您应该=在 for 循环中添加符号

for (int i = Num; i > 0; i--)

因此您可以包含数组的第一个元素（索引为 0 的元素）。

基本上，如果条件应如下所示：

if (generate.Length > Num)

和这样的循环：

for (int i = Num; i >= 0; i--)

Answer 2

尝试 19 而不是 20，因为当您计算数组中的元素时，您从零开始。

Answer 3

这将让您在文本框中放置 20

            Num = int.Parse(textBox1.Text);
            if (Num <= 20)
            {
                if (generate.Length >= Num)
                {
                    for (int i = Num - 1; i >= 0; i--)
                    {

                        name = generate.ElementAt(i);
                        listBox1.Items.Add(name); // Print it to list1 
                        generate = generate.Where(s => s != name).ToArray(); // Delete name after using
                    }
                }
                else MessageBox.Show("Sorry, remaining names =" + generate.Length);
                listBox2.Items.Clear();
                listBox2.Items.AddRange(generate);

            }
            else MessageBox.Show("Max name is 20!");