How to stop my Thread in a function from a other function?

Question

I need to stop a Thread when my timer is done.

But this all from a other function.

My Timer starts after Pressing Key: L. a Messagebox appears "Timer started" and my Thread starts too. after 10 seconds, Timer stops with message but my Thread is still running. What can i do? :/

void StartFunction()
{    
    Thread AB = new Thread(SEARCHING) { IsBackground = true };
    AB.Start();

}
void StopFunction()
{
    Thread AB = new Thread(SEARCHING);
    AB.Abort();
}

private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.L)
    {
        StartFunction();
        timer1.Start();
        MessageBox.Show("Timer 1 started!");
    }
}
int time = 0;
private void timer1_Tick(object sender, EventArgs e)
{          
   time++;
   if (time == 10 && timer1.Enabled)
   {
        StopFunction();
        MessageBox.Show("Timer 1 stoped!");
        timer1.Stop();                        
        time = 0;
   }                            
}

Answer 1

Idle_Mind is correct on how to accomplish this. Below is a working example using .NET 6.

One important detail is to use Thread.Join(). This will tell your caller to block until the loop is exited and the method returns.

Here I use the command console to key off the switching of the _running flag. You can do the same with a timer or whatever else. Keep in mind that you should probably also implement IDisposable in your class with the thread in it and set _running to false and do the join there as well. That way, you can instantiate the object with using.

namespace Lala
{
    class AB : IDisposable
    {
        private bool _running = false;
        private readonly Thread _thread;

        public AB() => _thread = new Thread(Method);
        private void Method()
        {
            while (_running)
            {
                Console.WriteLine("doing stuff");
                Thread.Sleep(1000);
            }
        }

        public void StartMethod()
        {
            _running = true;
            _thread.Start();
        }

        public void StopMethod()
        {
            _running = false;
            _thread.Join();
        }

        public void Dispose() => StopMethod();

    }
    public class Program
    {
        public static void Main()
        {
            Console.WriteLine("Launching a Thread. Press any key to stop it");
            using AB ab = new(); 
            // AB ab = new(); // if using is not appropriate
            ab.StartMethod();
            while (!Console.KeyAvailable)
                Thread.Sleep(10);
            // ab.StopMethod();// if using is not appropriate
        }
    }
}

Answer 2

Using modern methods you would write something like

private async void Form1_KeyDown(object sender, KeyEventArgs e)
{
    var cts = new CancellationTokenSource(10000);
    var task = Task.Run(() => Search(cts.Token));
    try
    {
        var result = await task;
        // handle result
    }
    catch (OperationCanceledException)
    {
        // handle cancelled
    }
    catch (Exception)
    {
        // handle other exceptions
    }
}

public int Search(CancellationToken cancel)
{
    while (true)
    {
        cancel.ThrowIfCancellationRequested();
        // Do searching
        if (found)
            return result;
    }
}

This would use thread pool threads instead of dedicated threads, and avoids the need to manually managing a timer. It also makes it easy to handle the result from the operation, if there are any.

Answer 3

Unfortunately, everything posted before didn't work for me or i just had not understand what i have to do.

Iam a C# Novice and I have a hard time understanding technical terms.

But i found a solution to make this possible.

This stops not the Thread but it Stops the while there has a function in a Thread.

First set a bool on top under public partial class:

    public partial class Form1 : Form
    {
       private volatile bool m_StopThread;

then you have to give your while in the function this:

while (!m_StopThread)

this means that your while is still not running until this is set true.

After this is set, you give your Button or Timer a function maybe like this:

        if ()
        {
            m_StopThread = true;
                            
        }

If this function is active your Thread will Start, because now its true and not longer false.

at the same way you can stop this again by set this function to false again.

If the solution I'm explaining has already been suggested, I thank you. And hope it helps others. But unfortunately I couldn't understand how to proceed now.

Thank you to those who go out of their way to help people like me every day. :)