C#

System.ArgumentOutOfRangeException: 'Index was out of range. Must be non-negative and less than the size of the collection.<br />
Parameter name: index'

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO.Ports;


namespace PlantMonitoringApp
{
    public partial class Form1 : Form
    {

        private SerialPort myport;
        private DateTime datetime;
        private string in_data;

        public Form1()
        {
            InitializeComponent();
        }

        private void start_btn_Click(object sender, EventArgs e)
        {
            myport = new SerialPort();
            myport.BaudRate = 9600;
            myport.PortName = port_name_tb.Text;
            myport.Parity = Parity.None;
            myport.DataBits = 8;
            myport.StopBits = StopBits.One;
            myport.DataReceived += Myport_DataReceived1;
            try
            {
                myport.Open();
                time_text_box.Text = "";

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error");
            }

            // timer1.Start();


        }
        void Myport_DataReceived1(object sender, SerialDataReceivedEventArgs e)
        {

            in_data = myport.ReadLine();

            this.Invoke(new EventHandler(displaydata_event));
            /*String dataFromArduino = myport.ReadLine();
            String[] dataTempHumidMoisture = dataFromArduino.Split();
            int Temperature = (int)(Math.Round(Convert.ToDecimal(dataTempHumidMoisture[0]), 0));
            //int Humidity = (int)(Math.Round(Convert.ToDecimal(dataTempHumidMoisture[1]), 0));
           // int SoilMoisture= (int)(Math.Round(Convert.ToDecimal(dataTempHumidMoisture[2]), 0));
            txtTemperature.Text = Temperature.ToString() + "C";
           // txtHumidity.Text = Humidity.ToString() + "%";
            //txtHumidity.Text = SoilMoisture.ToString() + "%";*/





        }
        private void displaydata_event(object sender, EventArgs e)
        {
            datetime = DateTime.Now;
            string time = datetime.Hour + ":" + datetime.Minute + ":" + datetime.Second;
            time_text_box.Text = time;

            


            string[] sensorData = in_data.Split(new char[] { ' ',' ',' '});
            List<string> tokens = new List<string>();
            foreach (string s in sensorData)
            {
                if (s.Length !=0)
                {
                    tokens.Add(s);
                }
            }
            
            
            txtTemperature.Text = tokens[0];
            txtHumidity.Text = tokens[1];
            txtSoil_moisture.Text = tokens[2];

    


        }

void AddTab()
        {
            bool existTabPage = false;
            UInt16 allChceked = 0;

            foreach (TabPage t in tabControl1.TabPages)
            {
                TabPage tabPage1 = new TabPage(tb_PlcUrl.Text);
                if (tabControl1.TabPages.ContainsKey(tb_PlcUrl.Text))
                {
                    existTabPage = true;
                }
                allChceked++;
            }

            if (!existTabPage && allChceked == tabControl1.TabCount)
            {
                TabPage tabPage1 = new TabPage();
                tabPage1.Name = tb_PlcUrl.Text;
                tabPage1.Text = tb_PlcUrl.Text;

                TextBox tb = new TextBox();

                tb.Location = new System.Drawing.Point(65, 19);
                tb.Size = new System.Drawing.Size(133, 20);
                tb.Text = tb_PlcUrl.Text;
                tb.BorderStyle = BorderStyle.None;
                tb.ReadOnly = true;
                tabPage1.Controls.Add(tb);

                Label labIpPlc = new Label();
                labIpPlc.Location = new System.Drawing.Point(18, 19);
                labIpPlc.Size = new System.Drawing.Size(133, 20);
                labIpPlc.Text = "PLC1";
                tabPage1.Controls.Add(labIpPlc);


                tabControl1.TabPages.Add(tabPage1);
            }
            else MessageBox.Show("Already exist : *" + tb_PlcUrl.Text);

        }

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{

    foreach (TabPage item in tabControl1.TabPages)
    {
        //Save everything from tabs
        Properties.Settings.Default.TabPages[i] = tabControl1.TabPages[i];
        i++;
    }
    Properties.Settings.Default.Save();
    Application.Exit();
}

How to handle PCB components layout in designing LED switching power supply?

if (rol > 99999999999) label1.Text = get3digit(rol) + " miliarde";
...
//where get3digit(rol) method is this:
        int get3digit(Int64 myVal)
        {
            char mg1 = myVal.ToString()[0];
            char mg2 = myVal.ToString()[1];
            char mg3 = myVal.ToString()[2];
            char[] chars = { mg1, mg2, mg3 };
            string mg = new string(chars);
            int i = int.Parse(mg);
            return i;
        }
//---RESULT is: "100 miliarde" (for this example) (but up to "999 miliarde");