Question

我的表单中有一个哈希表。所以基本上我有2个按钮添加和删除。当我将信息放入文本框并添加它时，将其添加到哈希表中。但是当我点击删除它删除它时，当它没有值时，它会显示错误。问题：我想要做的是，当我将信息放入 textBox1 （未添加到Hashtable中）时，它应该给出错误，否则如果已经添加了值，则应该删除它。

    public Form1()
    {
        InitializeComponent();
    }
    Hashtable Info = new Hashtable();

    private void button1_Click(object sender, EventArgs e)
    {
        string a = textBox1.Text;
        string b = textBox2.Text;
        if (a == "" && b == "" || a == "" || b == "")
        {
            MessageBox.Show("Missing Input!");
        }
        else
        {
            MessageBox.Show("Added successfully");
            label4.Text = a + " " + b;
        }

    }

    private void button4_Click(object sender, EventArgs e)
    {

        string a = textBox1.Text;
        string b = textBox2.Text;
        if (a == "")
        {
            MessageBox.Show("Missing Value");
        }
        else if(Info.ContainsKey(a)) // but this deletes it even if the value has not been added
        {
            MessageBox.Show(textBox1.Text + "has been removed");
            Info.Remove(a);
        }

    }

例如：如果我在Hashtable中添加2并尝试删除3，它仍然会删除它只是因为textBox中有一些值。

Answer 1

public Form1()
{
    InitializeComponent();
}
Hashtable Info = new Hashtable();

private void AddToHashTable_Click(object sender, EventArgs e)
{
    string a = textBox1.Text;
    string b = textBox2.Text;
    if (a == "" || b == "")
    {
        MessageBox.Show("Missing Input!");
    }
    else if(Info.ContainsKey(a) || Info.ContainsKey(b))
    {
       MessageBox.Show("Hash table already contain this key");
    }
    else
    {
        Info.Add(a);
        Info.Add(b);
        MessageBox.Show("Added successfully");
        label4.Text = a + " " + b;
    }

}

private void DeleteFromHashTable_Click(object sender, EventArgs e)
{

    string a = textBox1.Text;
    string b = textBox2.Text;
    if (a == "")
    {
        MessageBox.Show("Missing Value");
    }
    else if(Info.ContainsKey(a)) // but this deletes it even if the value has not been added
    {
        MessageBox.Show(a + " has been removed");
        Info.Remove(a);
    }
    else
    {
        MessageBox.Show(a + " is not part of the hash table");
    }

    //same check here for b
    if (b == "")
    {
        MessageBox.Show("Missing Value");
    }
    else if(Info.ContainsKey(b)) // but this deletes it even if the value has not been added
    {
        MessageBox.Show(b + " has been removed");
        Info.Remove(b);
    }
    else
    {
        MessageBox.Show(b + " is not part of the hash table");
    }


}

我稍微更改了代码。你错过了一些重要的事情。就像检查HashTable中的密钥是否已经存在于您尝试添加它们时一样。如果尝试添加现有密钥，则会发生异常。我也改变了方法的名称，你错过了在哈希表中添加两个文本框。

对删除哈希表的限制

1 个答案: