windows application blanks out

Hi nobrainer. What you said is exactly what I ment, maybe I wasn't very explicit. usb wanted to see how can he work with variables (value typed, like integers) across classes. I initially said you can't alter a variable of a main class through another, child one unless using an interface. But, if you pass a reference of that variable to a method that belongs to the child form, its original value will be altered. If there's something I'm missing I hope for your forgiveness. Cheers, A. L.

A.L. ! reference types are ALWAYS passed by reference. With no ref or out the method recieves a copy of the original reference (which could be considered pass ByValue). The only thing is... When you assign to a reference parameter it doesn't effect the original object. When you assign with ref or out the original object is effected as well.

Oh, I remembered there could be another way to accomplish what you want: you might use the "ref" or "out" keywords when passing paramteres to a function. Both ref and out specifies that the parameter is passed by reference, not by value.

To directly display information in Form1 within DrawRandomNumber class you must use an interface. If not, you can't access any of the properties or methods of Form1 unless they are declared as static. Another way to do this would be to have DRN class raise an event which would be handled in the Form1 class.

I will check the inteface thread. The only reason I return to the main program (the click_button method in Form1.cs) is becasue that is where I display the information in the form text boxes from the calculations made in the methods in the RandomNumber.cs file. Is there a way in the methods in the RandomNumber.cs to display information in the Form in From1.cs, or is this the same thing as working with the variable across .cs files? Thanks for all your help

Even like this, the answer remains the same. You can't access directly a variable contained in the main (or parent) class through a child class unless there would exist an inheritance between them. And as in C# you can't have multiple inheritance the remaining solution is to use interfaces (I've just spotted a new thread called "Interfaces...what's the deal" - take a look). Or, once again, declare the variable as static, although that would mean it can be accessed (and modified) from anywhere and if the code is larger and more complex you might modify it by accident. However, you should, first of all, make a sketch of your future program in your mind. If the params and the return values can be stored in the DrawRandomNumber class, why not do it? This way, the Draw(...) function will perform the calculations and will return the appropriate value(s) in its own class, without having to bother about the main (probably UI) class. Form there, the values can be accessed at any time.

Looks like I confused things. The testClass variable was my attempt to see how to create a variable that could be accessable to another class with out passing it. It has nothing to do with the actual program. That is why the drn.Draw method still has its parameters. The parameters max and pick in the Draw method come from the windows application form and are obtained all at once with a button click. I need the Draw method in a separate class (.cs file) to get that information and then the result of using that information be accessable back in the form1 class (form1.cs file)

First of all, I see that your Draw(...) function still has parameters and return-type. The idea was to remove this prameters and the return-type in order to create a new thread. Yet, if you want to keep this declaration of Draw(...) of course you won't be able to modify the testClass variable within the Draw function because (obvious, I think) it's declared in another class. Still, you can modify it in several ways: - by creating an interface between the two classes(check out the "Multiple forms Windows application" thread started on 11.05 in this forum) -declaring testClass as a static variable(this is also disussed in the above mentioned thread) -or simply increment testClass in Form1 class after the call made to drn.Draw(max,pick): line=drn.Draw(max,pick); testClass++; The last variant is suitable if testClass value doesn't depend on the succes of Draw(...) function. However, as the code you wrote doesn't seem too complex, you can "play" with the global variables as you desire (for example, the Draw function could return a bool value to show if it succedeed and the string which was previously returned would be read from within the Form1 class depending wether Draw returned true or false: public Class DrawRandomNumbers { string returned_string; ... bool Draw(int max, int pick) { ...//calcs returned_string=...;//whatever return true;//or return false } } //in Form1: { ... if(drn.Draw(max,pick)==true) MessageBox.Show(drn.returned_string,""); ... } However, choose one of the above, according to your needs. A.L.

You can tell I am new at this. I am not obtaining communication between the two class or the two .cs files. This is what I tried. In Form.cs: public class Form1 : System.Windows.Forms.Form { int testClass = 10;// global variable accessed in any method in the Form1 class private void buttonDraw_Click(object sender, System.EventArgs e) { textBoxMessages.Text += testClass.ToString() + "\r\n"; line = drn.Draw(max,pick); textBoxMessages.Text = testClass.ToString () + "\r\n"; ******* In DrawRandomNumbers.cs: public class DrawRandomNumbers { ... public string Draw(int max, int pick) { ... testClass += 1;//error: the name testClass does not exist in the class or namespace ... }

Sorry, what I ment was using not literally "extern" variables but global ones, declared in the beginning section of your class. You can use this instead of the parameters and instead of the return value. Something like this: class myClass { int param1,param2,...,paramn;//not necessary int but any type you want int return_value;//same as above public myClass() { ... } void draw() { ...;//do the same operations with param1,...,paramn global variables as if they were passed as parameters ... return_value=...;//whatever you want } } Now, each time you call the myClass.draw() function you just have to take care to modify param variables and, when finished, check the return_value variable. I don't think it's that hard. However, reply if it's still not woking.

My resource Microsoft Visual C Sharp .NET Step by Step Version 2003 eBook does not mention anything about extern variables. I searched Microsoft Visual Studio .NET 2003 help and it only spoke about extern methods. I Googled C# extern and every reference spoke about extern method declaration, but nothing on extern variables. Can you direct me to a tutorial on creating and useing extern variables between classes? I do not know where to begin with getting rid of sending variables to a method that then returns a value and still have it all work.

Hi! If you would perform a search for "Creating threads" topic in .NET VS, you would see that, I quote: "The ThreadStart delegate has no parameters or return value. This means that you cannot start a thread using a method that takes parameters, or obtain a return value from the method ... To pass data to a thread, create an object to hold the data and the thread method.". Indeed, I came upon the same problem you have and it's quite simply to solve it. Just make the Draw (or whatever its name is) function parameterless, and get the parameters from an extern variable(s) instead. Then you'll have: Thread thread=new Thread(new ThreadStart(drn.Draw)); thread.Priority= whatever level you desire thread.Start(); A. L.

I would suggest making a kind of loop(with timer intervals) and check each time if the thread has stopped. If it's stopped you can assign the values.

I, again, recommend you to read about multi-threading.... Or, at least, about Application.DoEvents().... or may be, just try and see what happends... Hard calculation applications are very hard to control.... and mostly, they don't need it. Users know that most programms are uncontrolable during calculation process. The worst, but easiest, way to make you application draws - insert into your cycle Application.DoEvents() and (MainForm).Refresh();

Is there a better way to maintain control of the windows application (move the window with the top bar, move a scroll bar up and down, click on a button) and have the calculations work at the same time without locking up the windows application until calculations are complete?

thread.Start() method doesn't return a value. It is always void. If you need to get result value of thread execution, one of the simpliest ways is to make a var for it... something like this: class { int thread_result; Thread calc_thread; void StartingThread() { calc_thread = new Thread(new ThreadStart(Thread_Main)); calc_thread.Priority = ThreadPriority.Lowest; cal_thread.Name = "Calc thread"; // for easy debugging calc_thread.Start(); while (calc_thread.Join(1000) == false) { // each second checking for thread is still working Application.DoEvents(); //do all event that were quenued within this second //update progress bar for example } //calculations are finished and thread_result var contains result value } void Thread_Main(){ //calculations..... thread_result = calculation_result; } } I recommend you to read about threading in MSDN. It's not a very easy thing to work with. Better to know more.

I created a separate class that does the calculations. I then created an instance of the class to call it: namespace LotteryProbability { ... DrawRandomNumbers drn = new DrawRandomNumbers(); ... private void buttonDraw_Click(object sender, System.EventArgs e) { ... line = drn.Draw(max,pick); ... } I tired this, but it is not allowed: private void buttonDraw_Click(object sender, System.EventArgs e) { ... Thread thread = new Thread( new ThreadStart( drn.Draw(max,pick) ) ); thread.Priority = ThreadPriority.Lowest; ... line = thread.Start(); ... }

Just use the using Threads; directive. You can make a new thread that can execute a the calculating method. using System; using System.Threading; namespace csConsole { class Threads { public static void Calculate() { //Do stuff } public static void Main() { Thread thread = new Thread( new ThreadStart( Calculate ) ); thread.Priority = ThreadPriority.Lowest; thread.Start(); Console.Read(); } } }

I do not know what a child thread is or setting priority.

I don't know will it help or not, but try to make a child thread for calculation. May be even make it with lower priority...

UPdate on problem Using big numbers that blank the window, if I touch any thing on the wind with a mouse click or move the window the program crashes and does not respond and must be closed with task manager.