Question

How to update thread parameter?

string str = "hello world"; 

private static Thread test = newThread(new ParameterizedThreadStart(invariant_loop));

private void Form1_Load(object sender, EventArgs e)
{
    test.Start(str);
}

private static void invariant_loop(object value)
{
    do
    {
        System.Threading.Thread.Sleep(1000);
        Console.WriteLine(value.ToString());
    }
    while (true);
}

private void button1_Click(object sender, EventArgs e)
{
    str = maskedTextBox1.Text; // update value ?
}

Answer 1

Since String is immutable data structure you can not doing such kind of operations (passing parameters). Use an other reference type or wrap string by a class with appropriate methods which able to modify underlying string field:

class TextWrapper
{   
   public string TextValue 
   { 
       get; 
       set; 
   }  
}

Define TextWrapper field on the level where you’ve defined str, then instantiate and pass instance of TextWrapper to a thread.

See very good article by Yoda: Parameter passing in C#