弄个防止listBox重复添加Items的小东西都脑大啊

Question

依然重复添加了，根本没办法防止重复的items ， 了个去啊。        private void button2_Click(object sender, EventArgs e)
        {
            IPHostEntry iphost = Dns.GetHostEntry(textBox1.Text);
                    //string ipaddress = ip.AddressFamily.ToString();
                    //listBox1.Items.Add(ipaddress);                 foreach (IPAddress ip in iphost.AddressList)
                  {
                     if(!listBox1.SelectedItems.Contains(ip.ToString()))
                     {
                         listBox1.Items.Add(ip.ToString());
                     }
                     else
                     {
                         MessageBox.Show("Item Exists!");   
                     }
                  }
        
        }

Answer 1

你还选中干嘛？？
private void button2_Click(object sender, EventArgs e)
{
       IPHostEntry iphost = Dns.GetHostEntry(textBox1.Text);
        foreach (IPAddress ip in iphost.AddressList)
        {
             if(!listBox1.Items.Contains(ip.ToString()))
              {
                   listBox1.Items.Add(ip.ToString());
              }
               else
               {
                     MessageBox.Show("Item Exists!");   
                }
      }
        
}

Answer 2

        private void button3_Click(object sender, EventArgs e)
        {
            List<string> lst = new List<string>();
            lst.Add("1");
            lst.Add("2");
            lst.Add("3");
            lst.Add("4");
            lst.Add("1");
            foreach (string str in lst)
            {
                if (!listBox1.Items.Contains(str))
                {
                    listBox1.Items.Add(str);
                }
                
            }
        }

Answer 3

够晕菜的，不知道SelectItems是虾米意思呢？

Answer 4

鸟解了，各位大哥，SelectedItems是选中的项。。