How To Transfer text from textbox to listbox c#

Add this in your button click method:

string[] parts = yourTextBox.Text.Split('#');
yourListBox.Items.AddRange(parts);

If you don't want that there can be empty elements in your listbox, try this:

string[] parts = yourTextBox.Text.Split(new char[] { '#' }, StringSplitOptions.RemoveEmptyEntries);
yourListBox.Items.AddRange(parts);

If you want to add 5 items on every button click (and only want 5 items in the listbox), try this:

int i = 0;
void yourButton_Click(object sender, EventArgs e)
{
    string[] parts = yourTextBox.Text.Split(new char[] { '#' }, StringSplitOptions.RemoveEmptyEntries);
    string[] partsToAdd = parts.Skip(5 * i).Take(5).ToArray();
    yourListBox.Items.Clear();
    yourListBox.Items.AddRange(partsToAdd);
    i++;
}