Wait for a button click inside foreach loop

Question

I want to create in my application a logic showed below

foreach(item in collection)
{
   //do something...wait for a button click (pause until button is clicked)
   //after button is clicked do another thing 
}

After hours of googling only one I know is that it can be handle with threads. I'm not familiar with this. If someone can explain issue it would be nice. I will appreciate any help

For your request let me explain more details

I want to compare the content in one of colums of DataTable object. Let say there are 10 rows in this column and in each row there is a differen word. I want to compare each word with the word put by user in TextBox control. The word of row 1 is displayed and user has to write it in text box. After put it in TextBox he must confirm it by clicking a button, and this will repeat 9 times.

foreach(DataRow dr in DataTab.Rows)<br/>
{
    string wordFromDB = dr["words"].ToString()
    //wait for a button click (pause until button is clicked)
    string wordFormTextBox = TextBox1.Text

    if( wordFormDB==wordFormTextBox)
    {
        Label1.Text="ok";
    }
    else
    {
        Label1.Text="nok";
    }
}

something like this. Of course if there is a different approach, I am interested in it.

Could you explain in more detail what the user interaction is and what is trying to be accomplished by the user. Perhaps there is another approach. — Tim Lloyd
– Tim Lloyd, Commented Nov 20, 2010 at 20:37
what kind of application is this? Winform? Is your button in a modal dialog? — Seattle Leonard
– Seattle Leonard, Commented Nov 20, 2010 at 20:38

Darin Dimitrov · Accepted Answer · 2010-11-20 20:41:11Z

1

This should be done in a separate thread because if you do it in the main thread you will basically kill the application. So you would start by declaring a synchronization event:

private static AutoResetEvent _wait = new AutoResetEvent(false);

and then queue a worker thread to do the job:

ThreadPool.QueueUserWorkItem(state =>
{
    foreach (item in (IEnumerable<Foo>)state)
    {
        // This will block the thread until the event is signaled
        _wait.WaitOne();

        // At this point the button was clicked => do something else
    }
}, collection);

And in the click of the button signal the event:

private void Button1_Click(object sender, EventArgs e)
{
    _wait.Set();
}

Remark: the foreach loop is a bit strange. I don't quite understand what you are trying to achieve with it.

answered Nov 20, 2010 at 20:41

Darin Dimitrov

1.0m276 gold badges3.3k silver badges3k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Aurea · Accepted Answer · 2010-11-20 20:39:25Z

0

Don't do that with threads. They are EVIL... Anyway, solving a problem as simple as this with something as complex and monstrous as threads is not good.

I would suggest to keep a variable, like lastItem, which will hold the index / key for the las item you went through. Then, when the button is clicked, call a function that will execute the needed action, increment the lastItem variable, and then repeat - wait for button click.

Another problem with your idea would be that it can potentially lead to an infinite loop - if the thread waiting for button click would somehow fail, your could would have NO idea, as it will be stuck in waiting for the press...

answered Nov 20, 2010 at 20:39

Aurea

8,0261 gold badge23 silver badges36 bronze badges

2 Comments

Seattle Leonard Over a year ago

threads are not evil. Sure, they can be difficult to deal with, but sometimes they are the right tool for the job and can add massive performance improvements to your application

sara Over a year ago

Threads are not evil, sure, but the Thread class and Explicitly dealing with spawning and synchronizing threads IS evil. Use a proper abstraction like Task. I would solve this requirement by awaiting an asynchronous method that uses a TaskCompletionSource<T>

Collectives™ on Stack Overflow

Wait for a button click inside foreach loop

2 Answers 2

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related