Question

I am trying to create a simple Network Tool to ping all possible IPs on your local subnet and provide a list of such IPs in a DataGridView. I am new to having to consider threading which is a good thing to come across as a budding programmer. Sorry, but you are probably going to have to do some explaining to me, but in my mind this should work. Before I tried putting it in a backgroundworker thread, the application would just hang and give me a “Not Responding”.

thanks ahead of time.

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        count = 0;
        for (int j = 1; j < 255; j++)
            for (int i = 1; i < 255; i++)
            {
                Ping ping = new Ping();
                PingReply pingreply = ping.Send(IPAddress.Parse(locip[0] + "." + locip[1] + "." + j + "." + i));

                if (pingreply.Status == IPStatus.Success)
                {
                    status = "o";
                    repAddress = pingreply.Address.ToString(); ;
                    repRoundtrip = pingreply.RoundtripTime.ToString();
                    repTTL = pingreply.Options.Ttl.ToString();
                    repBuffer = pingreply.Buffer.Length.ToString();

                    string[] lineBuffer = { status, repAddress, repRoundtrip, repTTL, repBuffer };
                    ipList.Rows.Add(lineBuffer);
                    count += 1;
                    progressBar.Value += 1;
                }

            }


    }

Answer 1

Part of the problem is that you are directly accessing a UI element from your background thread. The field progressBar is presumably a UI progress bar control and can only be safely accessed from the UI thread. You must use a call to .Invoke to set this value from the UI thread.

progressBar.Invoke(new MethodInvoker(UpdateProgressBarbyOne));
...

private void UpdateProgressBarByOne() {
  progressBar.Value += 1;  
}