How to add listbox selected item to textbox?

Hi,

 

I have below code and when I type something on textbox it will be selected from listbox.Like an autocomplete feature.Now I need to
get selected item from listbox to textbox? any idea how can I achieve it?

DataTable dt = new DataTable();
public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{

dt.Columns.Add("Id", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Rows.Add(1, "Foo");
dt.Rows.Add(2, "Hoo");
dt.Rows.Add(3, "Too");
dt.Rows.Add(4, "Fii");
dt.Rows.Add(5, "Fee");
dt.Rows.Add(6, "Fuu");
dt.Rows.Add(7, "Noo");

listBox1.DataSource = dt;
listBox1.DisplayMember = "Name";
listBox1.ValueMember = "Id";
listBox1.SelectionMode = SelectionMode.MultiExtended;
}

private void textBox1_TextChanged(object sender, EventArgs e)
{
DataTable clone = dt.Clone();
foreach (DataRow dr in dt.Select("Name like '" + textBox1.Text + "%'"))
{
clone.ImportRow(dr);
}
listBox1.DataSource = clone;
listBox1.DisplayMember = "Name";
listBox1.ValueMember = "Id";
//or
for (int i = 0; i < listBox1.Items.Count; i++)
{
listBox1.SetSelected(i, false);
if (listBox1.GetItemText(listBox1.Items[i]).StartsWith(textBox1.Text))
{
listBox1.SetSelected(i, true);
}
}
}

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{

//This code is not working

/* for (int i = 0; i < listBox1.Items.Count; i++)
{
if ((i + 1) < listBox1.Items.Count)
textBox1.Text += listBox1.Items[i] + ", ";
else
textBox1.Text += listBox1.Items[i];
}*/ 

}