Some C# code to read a serial port. Using this as a starting point for an Arduino project.

ReadSerialPort.cs

using System;
using System.IO.Ports;

namespace SerialReader
{
    class Program
    {
        static void Main(string[] args)
        {
            var reader = new ArduinoSerialReader("COM3");

            Console.ReadLine();
        }

        static void ListComPorts()
        {
            // Get a list of serial port names. 
            string[] ports = SerialPort.GetPortNames();

            Console.WriteLine("The following serial ports were found:");

            // Display each port name to the console. 
            foreach (string port in ports)
            {
                Console.WriteLine(port);
            }
        }
    }

    public class ArduinoSerialReader : IDisposable
    {
        private SerialPort _serialPort;

        public ArduinoSerialReader(string portName)
        {
            _serialPort = new SerialPort(portName);
            _serialPort.Open();
            _serialPort.DataReceived += serialPort_DataReceived;
        }

        void serialPort_DataReceived(object s, SerialDataReceivedEventArgs e)
        {
            Console.WriteLine(_serialPort.ReadLine());
        }

        public void Dispose()
        {
            if (_serialPort != null)
            {
                _serialPort.Dispose();
            }
        }
    }
}

thanks bro