How to create threads in C# ?

Threads can be created like other objects in C# using the 'new' keyword.

Thread th = new Thread(Write);

Thread class is available in System.Threading namespace.
We can start a thread using Start() method like.

th.Start();

Above I have just created and started a thread. Now what task a thread have to do, can be defined it in five different ways.

1. By passing delegate to action or method delegate in thread constructor.

Thread firstThread = new Thread(() =>
{
 Console.WriteLine("ThreadedMinds => first thread.");
});
firstThread.Start();

2. By passing the method name as an argument to thread constructor.

Thread secondThread = new Thread(WriteSecond);
secondThread.Start();
private static void WriteSecond()
{
 Console.WriteLine("ThreadedMinds => second thread.");
} 

3. By passing object of ParameterizedThreadStart class as an argument to thread constructor.

Thread thirdThread = new Thread(new ParameterizedThreadStart(WriteThird));
thirdThread.Start( "ThreadedMinds => third thread.");
private static void WriteThird(object message)
{
 Console.WriteLine(message.ToString());
}

4. By using TPL(Task Parallel Library), which is a new collection of useful classes, making parallel programming easier to do and understand, but also offers lighter weight objects when compared to the classic threading.

Task fourthThread = new Task(() =>
{
 Console.WriteLine("ThreadedMinds => fourth thread.");

});
fourthThread.Start();

Task class is available in System.Threading.Tasks namespace. 

5. By using QueueUserWorkItem method of ThreadPool class.

ThreadPool.QueueUserWorkItem(new WaitCallback(WriteFifth), "ThreadedMinds => fifth thread.");
private static void WriteFifth( object message)
{
 Console.WriteLine(message.ToString());
}

ThreadPool class is available in System.Threading namespace. 

Program:

using System;
using System.Threading;
using System.Threading.Tasks;
namespace Threads
{
  class Program
  {
    static void Main(string[] args)
    {
      Thread firstThread = new Thread(() =>
      {
        Console.WriteLine("ThreadedMinds => first thread.");
      });
      firstThread.Start();
      Thread secondThread = new Thread(WriteSecond);
      secondThread.Start();
      Thread thirdThread = new Thread(new ParameterizedThreadStart(WriteThird));
      thirdThread.Start("ThreadedMinds => third thread.");
      Task fourthThread = new Task(() =>
      {
        Console.WriteLine("ThreadedMinds => fourth thread.");
      });
      fourthThread.Start();
      ThreadPool.QueueUserWorkItem(new WaitCallback(WriteFifth), "ThreadedMinds => fifth thread.");    
      Console.ReadKey();
    }
    private static void WriteSecond()
    {
      Console.WriteLine("ThreadedMinds => second thread.");
    }
    private static void WriteThird(object message)
    {
      Console.WriteLine(message.ToString());
    }
    private static void WriteFifth(object message)
    {
      Console.WriteLine(message.ToString());
    }
  }
}

Output:

Download sample source code : Create_Threads.rar