c# Simple TASK Cancel

Question

I'm tying stop thread by nothing works. I was trying on 100 ways. What is wrong ? It is irritating

(I have to write some text here because stackoverflow.com don't allow me to send this post)(I have to write some text here because stackoverflow.com don't allow me to send this post)(I have to write some text here because stackoverflow.com don't allow me to send this post)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication5
{
    public partial class Form1 : Form
    {
        private static CancellationTokenSource cts = new CancellationTokenSource();
        private CancellationToken ct = cts.Token;

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Task.Factory.StartNew(() => 
            {
                work_for_task(ct);
            }, this.ct);
        }

        private void work_for_task(CancellationToken ct)
        {
            if (ct.IsCancellationRequested)
            {
                ct.ThrowIfCancellationRequested();
            }

            for (int i = 0; i < 5; i++)
            {
                if (richTextBox2.InvokeRequired)
                {
                    richTextBox2.Invoke((MethodInvoker)delegate
                    {
                        richTextBox2.AppendText("I AM IN: " + Thread.CurrentThread.Name + "\n");
                    });

                    Thread.Sleep(1400);
                }
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            MessageBox.Show("CANCELED");
            cts.Cancel();
        }
    }
}

Answer 1

Just this instead of your work_for_task method:

private void work_for_task(CancellationToken ct)
{
    for (int i = 0; i < 5; i++)
    {
        if (ct.IsCancellationRequested)
        {
            return; 
        }
        if (richTextBox2.InvokeRequired)
        {
            richTextBox2.Invoke((MethodInvoker)delegate
            {
                richTextBox2.AppendText("I AM IN: " + Thread.CurrentThread.Name + "\n");
            });

            Thread.Sleep(1400);
        }
    }
}