In this blog we will move items from one list box to other and vice-versa. But if first list box contains some duplicate values it will not allowed to move, rather we will get a message item exits.

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 WindowsFormsApplication1

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

private void Form1_Load(object sender, EventArgs e)

{

listBox1.Items.Add("Raj");

listBox1.Items.Add("Raj");

listBox1.Items.Add("Raju");

listBox1.Items.Add("Rahul");

listBox1.Items.Add("Harry");

listBox1.Items.Add("Ben");

listBox1.Items.Add("Ian");

}

private void btn_right_Click(object sender, EventArgs e)

{

if (listBox2.Items.Contains(listBox1.SelectedItem) == true)

{

MessageBox.Show("Item Exits");

}

else

{

listBox2.Items.Add(listBox1.SelectedItem);

int i = 0;

i = listBox1.SelectedIndex;

listBox1.Items.RemoveAt(i);

}

}

private void btnleft_Click(object sender, EventArgs e)

{

listBox1.Items.Add(listBox2.SelectedItem);

int i = 0;

i = listBox2.SelectedIndex;

listBox2.Items.RemoveAt(i);

}

}

}