How to fix 'The name 'k' does not exist in the current context' error?

Question

I only get the System.IndexOutOfRangeException error when running the solution normally but is all okay when stepping into through the whole loop.

I have tried the to catch the exception but no joy.

private void button1_Click(object sender, EventArgs e)
        {
            for (int j = 0; j < jobs.Length; j++)
            {
                if (jobs[j].JobID == false)
                {
                    for (int k = 0; k < threads.Length; k++)
                    {
                        if (threads[k] != null)
                        {
                            if (!(threads[k].ThreadState == ThreadState.Stopped) | !(threads[k].ThreadState == ThreadState.Unstarted))
                            {
                                continue;
                            }
                        }

                        try
                        {
                            threads[k] = new Thread(() => CountUp("ftp://ftp.net" + jobs[j].FTPFolder, HomePath + jobs[j].localFolder, j));
                            threads[k].Name = "Thread " + j + "¦ ID: " + threads[k].ManagedThreadId.ToString();
                            jobs[j].JobID = true;
                            //threads[k].Start();
                            break;
                        }
                        catch (Exception exception)
                        {
                            Console.WriteLine(exception);
                            throw;
                        }

                    }
                }
            }
            StartThreads();
        }

I expect all threads in the threads[] array to be initialised if jobs[].JobID is false.

Below is the CountUp() method:

        private void CountUp(string ftppath,string localFile, int jobsID)
        {
            //string conf="";
            NumberThreads++;
            //string ftpPath = "ftp://ftp.Rxsystems.net" + conf.Split('¦')[1];
            //string downloadPath = HomePath + conf.Split('¦')[0] + "\\";

            string ftpPath = ftppath;
            string downloadPath = localFile;

            List<string> MSI = new List<string>(KD.FTP.Class.ListFiles(ftpPath,
                FTPuser, FTPpass));

            if (MSI.Count > 0)
            {
                KD.File.Class.Logger(Thread.CurrentThread.Name + ", " + MSI.Count + " Files in " + ftpPath, CurDir + "\\log.txt");

                this.textBox1.AppendText(Thread.CurrentThread.Name + ", " + MSI.Count + " Files in " + ftpPath);
                //this.textBox1.AppendText("\n\r");
                int count = 0;
                foreach (string ftpFile in MSI)
                {
                    KD.FTP.Class.Download(ftpPath + ftpFile,downloadPath + "\\" + ftpFile, FTPuser,FTPpass);
                    count++;
                    KD.File.Class.Logger(Thread.CurrentThread.Name + ", " + "Downloaded " + count + "/" + MSI.Count + " Files - " + ftpFile, CurDir + "\\log.txt");
                    this.textBox1.AppendText(Thread.CurrentThread.Name + ", " + "Downloaded " + count + "/" + MSI.Count + " Files - " + ftpFile);
                    //this.textBox1.AppendText("\n\r");
                }
            }


            NumberThreads--;
            jobs[jobsID].JobID = false;
        }

The below initialises threads[] and jobs[]:

private void Form1_Load(object sender, EventArgs e)
        {
            Form1.CheckForIllegalCrossThreadCalls = false;

            if (File.Exists(CurDir + "\\FTPpaths.config"))
            {
                foreach (string line in File.ReadAllLines(CurDir + "\\FTPpaths.config"))
                {
                    if (!string.IsNullOrEmpty(line))
                    {
                        ConfigPaths.Add(line.Split('¦')[0] + "¦" + line.Split('¦')[1]);
                    }
                }

                if (ConfigPaths.Count > 0)
                {
                    jobs = new Jobs[ConfigPaths.Count];

                    for (int j = 0; j < ConfigPaths.Count; j++)
                    {
                        jobs[j] = new Jobs();
                        jobs[j].FTPFolder = ConfigPaths[j].Split('¦')[1];
                        jobs[j].localFolder = ConfigPaths[j].Split('¦')[0];
                        jobs[j].JobID = false;
                    }

                    threads = new Thread[jobs.Length];

                }


                timer1.Enabled = true;
            }
            else
            {
                Application.Exit();
            }
        }

Answer 1

From what I can see the problem is with j variable which is captured from closure into delegate passed to new Thread. It's well know problem when actual delegate execution references the variable in state after the loop execution so it's supposed to effectively contain jobs.Length value which is out of range. To fix you need to introduce a local variable inside the loop to copy j value in, and then use this variable instead of j as index of jobs inside the delegate passed to the Thread constructor:

try
{
    var jobIdx = j;
    threads[k] = new Thread(() => CountUp("ftp://ftp.net" + jobs[jobIdx].FTPFolder, HomePath + jobs[jobIdx].localFolder, jobIdx));
    ...
    // other stuff

}
catch (Exception exception)
{
    Console.WriteLine(exception);
    throw;
}