Question

I have a thread started and I want the user to be able to interrupt it by clicking a button on the form. I found the following code and it demonstrates what I want nicely.

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
using System.Threading;

namespace ExThread {

public partial class MainForm : Form {
    public int clock_seconds=0;

    [STAThread]
    public static void Main(string[] args) {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new MainForm());
    }

    public MainForm() {
        InitializeComponent();

        Thread thread_clock = new Thread(new ThreadStart(Thread_Clock));
        thread_clock.IsBackground = true;
        thread_clock.Start();
    }

    delegate void StringParameterDelegate (string value);

    public void Update_Label_Seconds(string value) {
        if (InvokeRequired) {
            BeginInvoke(new StringParameterDelegate(Update_Label_Seconds), new object[]{value});
            return;
        }
        label_seconds.Text= value + " seconds";
    }       

    void Thread_Clock() {
        while(true) {
            clock_seconds +=1;
            Update_Label_Seconds(clock_seconds.ToString());
            Thread.Sleep(1000);
        }
    }

    private void btnStop_Click(object sender, EventArgs e)
    {

    }
}
}

I have added the btnStop method. What code needs to be added to stop the thread_clock thread.

Thanks.

Answer 1

First, the thread needs to be able to recognize that it should end. Change

void Thread_Clock() {
    while(true) {

to

bool endRequested = false;
void Thread_Clock() {
    while(!endRequested) {

And then set endRequested to True in your button click handler.

private void btnStop_Click(object sender, EventArgs e)
{
    endRequested = true;
}

Note that for this specific case, it is probably more appropriate to use a Timer

http://msdn.microsoft.com/en-us/library/system.windows.forms.timer.aspx

Simply start and stop the timer as desired. You would update the clock from the timer’s Tick() event.