How to access same variable in Main() and in thread proc in another class?

[ejbaker]

This example has a member variable in the class "Program" named "ProgramDat" that I want to access from a thread in another class.

I want the thread to be able to change that memory location and have Program::Main() see the update as well as Program::Main() change the variable and have the thread see it.

ref doesn't seem to do it. Is there another construct I could use?

(And I recognize the potential race conditions here. I left out any synchronization techniques for simplicity of this post.)

Thanks.

using System;
using System.Threading;

public class Program
{
    static ManualResetEvent ExitEvent;
    static MyThread t;
    static int ProgramDat;

    public static void Main()
    {
        ExitEvent = new ManualResetEvent(false);
        ProgramDat = 12;      // initialize to some value
        t = new MyThread(ExitEvent, ref ProgramDat);

        Thread.Sleep(1500);     // let MyThread run a bit

        // Main() doesn't see the changes MyThread::RunLoop() made
        Console.WriteLine("Main just before setting to 500, MyFormDat={0}", ProgramDat);
        ProgramDat = 500;       // and this change is not seen in MyThread::RunLoop();
        Console.WriteLine("Main just set MyFormDat={0}", ProgramDat);
        Thread.Sleep(2000);
        Console.WriteLine("Just prior to telling thread to exit, MyFormDat={0}", ProgramDat);
        ExitEvent.Set();
        Thread.Sleep(500);  // wait to let MyThread::RunLoop() finish
        Console.WriteLine("main leaving.  MyFormDat={0}", ProgramDat);
     }
}


public class MyThread
{
    ManualResetEvent e;   
    Thread t;
    int MyThreadDat;

    public MyThread(ManualResetEvent ev, ref int FromProgramDat)
    {
        e = ev; 
        MyThreadDat = FromProgramDat;

        t = new Thread(RunLoop);
        t.Start();
    }

    public void RunLoop()
    {
        while (true)
        {
            if (e.WaitOne(300) == true)
            {
                Console.WriteLine("RunLoop leaving!");
                return;
            }
            else
            {
                Console.WriteLine("tic.  iFormDat={0}", MyThreadDat);
                MyThreadDat++;      // change it each loop but I can't get Main() to see this change
            }
        }
    }
}

[Arjay]

Since you are using a static variable, you could make it public. That way you could access it directly without having to pass it to the thread. In your thread, change the MyThreadDat to:

MyThreadDat = Program.ProgramDat;

Btw, this would be okay for your simple example (ignoring race conditions). For real code, I would do something more robust.

[CodeCake]

What i would recommend is to use private variables and public getters and setters

[Arjay]

What i would recommend is to use private variables and public getters and setters

For C#, you might want to read up on properties and auto properties.

[CodeCake]

Idk sorry i talk based on my java knowledge