C#

<br />
private void button1_Click(object sender, EventArgs e)<br />
        {<br />
            try<br />
            {<br />
                serialPort1.BaudRate = 4800;<br />
                serialPort1.PortName = comboBox1.SelectedItem.ToString();<br />
                serialPort1.Open();<br />
                timer1.Enabled = true;<br />
            }<br />
            catch (Exception ex)<br />
            {<br />
                MessageBox.Show(ex.Message);<br />
            }<br />
<br />
        }<br />
<br />
 private void timer1_Tick(object sender, EventArgs e)<br />
        {<br />
            try<br />
            {<br />
                string data = serialPort1.ReadExisting();<br />
                listBox1.Items.Add(data);<br />
            }<br />
            catch(Exception ex)<br />
            {<br />
                MessageBox.Show(ex.Message);<br />
            }<br />
        }<br />
<br />

public partial class CompanyListControl : ListBox<br />
    {<br />
        int _previousIndex = 0;<br />
        public CompanyListControl()<br />
        {<br />
            InitializeComponent();<br />
            this.DrawMode = DrawMode.OwnerDrawFixed;<br />
        }<br />
        protected override void OnDrawItem(DrawItemEventArgs e)<br />
        {<br />
            base.OnDrawItem(e);<br />
            if (!DesignMode)<br />
            {<br />
                e.DrawBackground();<br />
                if (this.SelectedIndex == e.Index)<br />
                {<br />
                    if (_previousIndex != e.Index)<br />
                    {<br />
                        InvalidateItem(_previousIndex);<br />
                        DrawSelected(e);<br />
                        _previousIndex = e.Index;<br />
                    }<br />
                }<br />
                else<br />
                {<br />
                    DrawUnselected(e);<br />
                }<br />
            }<br />
        }<br />
        public void InvalidateItem(int index)<br />
        {<br />
            if ((index < 0) || (index >= this.Items.Count))<br />
                return;<br />
            object InvalidatedObject = this.Items[index];<br />
            this.Items.RemoveAt(index);<br />
            this.Items.Insert(index, InvalidatedObject);<br />
        }<br />
        private void DrawSelected(DrawItemEventArgs e)<br />
        {<br />
            if (e.Index == -1) return;<br />
            int RowWidth = e.Bounds.Width;<br />
            Font f = new Font("Arial Black", e.Font.Size);<br />
            Size s = TextRenderer.MeasureText("C", f);<br />
            int SalesPos = 0;<br />
            float PurchasePos = s.Width * 0.7f;<br />
            float TextPos = PurchasePos * 2;<br />
            int VerticalPos = e.Bounds.Top;<br />
            e.Graphics.DrawString(this.Items[e.Index].ToString(), e.Font, Brushes.White, TextPos, e.Bounds.Top);<br />
            e.Graphics.DrawString("C", f, Brushes.Red, SalesPos, VerticalPos);<br />
<br />
        }<br />
        private void DrawUnselected(DrawItemEventArgs e)<br />
        {<br />
            int RowWidth = e.Bounds.Width;<br />
            Font f = new Font("Arial Black", e.Font.Size);<br />
            Size s = TextRenderer.MeasureText("C", f);<br />
            int SalesPos = 0;<br />
            float PurchasePos = s.Width * 0.8f;<br />
            float TextPos = PurchasePos * 2;<br />
            int VerticalPos = e.Bounds.Top;<br />
            e.Graphics.DrawString(this.Items[e.Index].ToString(), e.Font, Brushes.Black, TextPos, e.Bounds.Top);<br />
            e.Graphics.DrawString("C", f, Brushes.Red, SalesPos, VerticalPos);<br />
        }<br />
        protected override void OnSelectedIndexChanged(EventArgs e)<br />
        {<br />
            base.OnSelectedIndexChanged(e);<br />
            this.Invalidate();<br />
        }<br />
    }

class Test
{

Console.WriteLine("1:Add\n2:Sub\n3:Mult:\n4:Div");
Console.WriteLine();
Console.WriteLine("Press 9 to Exit or Enter to Continue ");

string s=Console.ReadLine();

....

}