c# Monitor 类中的多线程

Question

Why do i get the output 1,1,2,3,4,5,6,7,8,9,10 when i use value as lokalvar and the correct ouput 1,2,3,4,5,6,7,8,9,10 when "value" is membervar?

i cant figure out why this happens. Thanks for any explanantions ;)

class Beispiel_3
{

int value = 0;

public void Execute_Threads()
{
// why is the out put wrong when i ise the varibale "value" here?
//===============================================================
    while (true)
    {
        Monitor.Enter(this);

        value++;
        if (value > 20)
            break;
        Console.WriteLine("Zahl = {0}  | Thread = {1}", value, Thread.CurrentThread.GetHashCode().ToString());
        Monitor.Exit(this);

    }

}
public void Execute_MainThread()
{
    Thread thread1, thread2;
    thread1 = new Thread(Execute_Threads);
    thread2 = new Thread(Execute_Threads);
    thread1.Start();
    thread2.Start();

    Console.ReadLine();
}
static void Main(string[] args)
{
    Beispiel_3 bsp3 = new Beispiel_3();
    bsp3.Execute_MainThread();

}

Answer 1

You have one class Beispiel_3 in which you start two threads. If you declare value as a member of class Beispiel_3 both threads use this one value and increase it more or less by turns. If you declare it in your method Execute_Threads each thread has its own variable value and always increase only his own variable value .