Question

我正在尝试在C＃中创建一个控件数组，但Visual Studio Express不合作。我在运行时收到消息：

对象引用未设置为对象的实例。

错误发生在下面的箭头上。我如何使这项工作？

public partial class Protocoltool : Form
{
    // ... other stuff

    // doesn't seem to make instances as I expect it would
    // class String_Entry is defined lower
    public String_Entry[] pt_entries = new String_Entry[NB_ENTRIES];

    // Constructor for class protocol tool
    public Protocoltool()
    {
        InitializeComponent();

        // tried to make instances here but still doesn't work
        //pt_entries = new String_Entry[NB_ENTRIES];

        // Add the supposedly instanciated control in a tableLayoutPanel
        EntriesGuiAdd();

        // ... other stuff
    }

    private void EntriesGuiAdd()
    {
        for (int i = 0; i < NB_ENTRIES; i++)
        {
            // tried to make instances here but still doesn't work
            //pt_entries[i].Create();

            // tried to make instances here directly, but still doesn't work

-----------＆gt; pt_entries [i] .textbox = new System.Windows.Forms.TextBox（）; pt_entries [i] .send = new System.Windows.Forms.Button（）;

            //tableLayoutPanel1.Controls.Add(pt_entries[i].textbox, 0, i);
            //tableLayoutPanel1.Controls.Add(pt_entries[i].send, 1, i);
        }
    }
} // end of protocoltool class

public class String_Entry
{
    public TextBox textbox;
    public Button send;
    public int sequential_counter;

    // A constructor here doesn't work at all

    /*
    ... so I put the constructor here instead, but still it doesn't work
    public void Create()
    {
        Console.WriteLine("creating entry");
        // tried to make instances here but still doesn't work
        textbox = new TextBox();
        send = new Button();
        send.Click += new System.EventHandler(this.bSend_Click);
    }
    */

    // ... other functions

}

Answer 1

您需要初始化pt_entries[i]，然后才能引用它的任何属性。

pt_entries[i] = new String_Entry();
pt_entries[i].textbox = new System.Windows.Forms.TextBox(); 
pt_entries[i].send = new System.Windows.Forms.Button();

C＃麻烦实施控制

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