C# Program to create a Simple Thread

In C#, a thread represents a separate execution path that can run concurrently with other threads. The System.Threading.Thread class allows you to create and manage threads in your application.

To create a simple thread, you define a method that contains the code you want to execute, then create a Thread object using a ThreadStart delegate that points to your method.

Syntax

Following is the syntax for creating a thread −

Thread threadName = new Thread(new ThreadStart(methodName));
threadName.Start();

You can also use the simplified syntax −

Thread threadName = new Thread(methodName);
threadName.Start();

Basic Thread Creation

Here's how to create a simple thread that executes a method multiple times −

using System;
using System.Threading;

class Demo {
    public void myThread() {
        for (int i = 0; i < 3; i++) {
            Console.WriteLine("My Thread");
        }
    }
}

class NewThread {
    public static void Main() {
        Demo d = new Demo();
        Thread thread = new Thread(new ThreadStart(d.myThread));
        thread.Start();
        thread.Join(); // Wait for thread to complete
        Console.WriteLine("Main thread finished");
    }
}

The output of the above code is −

My Thread
My Thread
My Thread
Main thread finished

Using Lambda Expression

You can also create threads using lambda expressions for simpler code −

using System;
using System.Threading;

class Program {
    public static void Main() {
        Thread thread = new Thread(() => {
            for (int i = 1; i <= 5; i++) {
                Console.WriteLine($"Thread execution: {i}");
                Thread.Sleep(1000); // Pause for 1 second
            }
        });

        thread.Start();
        Console.WriteLine("Main thread continues...");
        thread.Join();
        Console.WriteLine("Thread completed");
    }
}

The output of the above code is −

Main thread continues...
Thread execution: 1
Thread execution: 2
Thread execution: 3
Thread execution: 4
Thread execution: 5
Thread completed

Multiple Threads Example

Here's an example showing multiple threads running concurrently −

using System;
using System.Threading;

class MultiThreadDemo {
    public static void WorkerThread(object threadName) {
        for (int i = 1; i <= 3; i++) {
            Console.WriteLine($"{threadName}: Task {i}");
            Thread.Sleep(500);
        }
    }

    public static void Main() {
        Thread thread1 = new Thread(WorkerThread);
        Thread thread2 = new Thread(WorkerThread);

        thread1.Start("Thread-A");
        thread2.Start("Thread-B");

        thread1.Join();
        thread2.Join();

        Console.WriteLine("All threads completed");
    }
}

The output of the above code is −

Thread-A: Task 1
Thread-B: Task 1
Thread-A: Task 2
Thread-B: Task 2
Thread-A: Task 3
Thread-B: Task 3
All threads completed

Key Methods

Conclusion

Creating threads in C# is straightforward using the Thread class and ThreadStart delegate. Use Start() to begin execution and Join() to wait for completion. Threads enable concurrent execution, improving application performance for CPU-intensive or I/O operations.