C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace ArduinoSerialTemp
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            serialPort1.BaudRate = 9600;
            serialPort1.PortName = "COM44";
            serialPort1.Open();

            serialPort1.Write("*1C0");
            serialPort1.Write("\r");

            serialPort1.DataReceived += serialPort1_DataReceived;
        }

        private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            string line = serialPort1.ReadLine();
            this.BeginInvoke(new LineReceivedEvent(LineReceived), line);
        }

        private delegate void LineReceivedEvent(string line);
        private void LineReceived(string line)
        {
            textBox1.Text = line;
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (serialPort1.IsOpen) serialPort1.Close();
        }

        private void serialPort1_ErrorReceived(object sender, System.IO.Ports.SerialErrorReceivedEventArgs e)
        {
            serialPort1.Close();
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }
    }

}

string strA = "Hello world!";
            string strB = "Hello world!";
            Console.WriteLine("ReferenceEquals(strA, strB) = {0}",
                             Object.ReferenceEquals(strA, strB)); // true

if(strA==strB)