Question

I have created a console application. I want to make the label (on the form) display whatever I type in the console, but the console hangs when I run the form.

code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace ConsoleApplication1
{
    class Program
    {
        Label a;
        static void Main(string[] args)
        {
            Form abc = new Form(); 
            Label a = new Label();
            a.Text = "nothing";
            abc.Controls.Add(a);
            Application.Run(abc);
            System.Threading.Thread t=new System.Threading.Thread(Program.lol);
            t.Start();


        }
        public static void lol()
        {
            Program p = new Program();
            string s = Console.ReadLine();
            p.a.Text = s;
            lol();
        }


    }
}

Answer 1

Application.Run will block until the form has closed. So you should call that on a separate thread.

However, your UI will then be executing on that separate thread – and you mustn’t “touch” a UI element from a thread other than the UI thread, so after calling Console.ReadLine(), you’ll need to use Control.Invoke or Control.BeginInvoke to make changes in the UI.

Additionally, you’re currently declaring a local variable called a, but never assigning a value to Program.a.

Here’s a complete version which works:

using System;
using System.Threading;
using System.Windows.Forms;

class Program
{
    private Program()
    {
        // Actual form is created in Start...
    }

    private void StartAndLoop()
    {
        Label label = new Label { Text = "Nothing" };
        Form form = new Form { Controls = { label } };
        new Thread(() => Application.Run(form)).Start();
        // TODO: We have a race condition here, as if we
        // read a line before the form has been fully realized,
        // we could have problems...

        while (true)
        {
            string line = Console.ReadLine();
            Action updateText = () => label.Text = line;
            label.Invoke(updateText);
        }
   }

    static void Main(string[] args)
    {
        new Program().StartAndLoop();
    }
}