How to use ListBox Control in Windows Application C# .Net

Add, Clear,Remove with List Box Control in Windows Application………………

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

namespace TestListBox

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

//add new item to ListBox(text from input TextBox) and clear input TextBox...

private void btnAdd_Click(object sender, EventArgs e)

{

if (txtaddSubject.Text != "" && txtaddSubject.Text != null)

{

listBoxSubject.Items.Add(txtaddSubject.Text);

txtaddSubject.Text = String.Empty;

// txtaddSubject.Text = "";

//txtaddSubject.Clear();

}

else

{

MessageBox.Show("Please fill  TextBox Field", "Missing Information", MessageBoxButtons.OK, MessageBoxIcon.Error);

}

}

//code for remove  item in ListBox if one is selected.............

private void btnRemove_Click(object sender, EventArgs e)

{

if (listBoxSubject.SelectedIndex != -1)

listBoxSubject.Items.RemoveAt(listBoxSubject.SelectedIndex);

}

//code for clear all item in ListBox.............

private void btnClear_Click(object sender, EventArgs e)

{

listBoxSubject.Items.Clear();

}

//code for exit Application.............

private void btnExit_Click(object sender, EventArgs e)

{

Application.Exit();

}

}

}