Text box text update

Sam

To solve a more complex c# issue in VS2010 Win7, I devised a simple test app:
I have a winform with a textbox and a button.
I have a loop that is supposed to write numbers into the text box.
When I run the program (hit the button), no numbers are being written to the textbox until the 10 seconds elapse, reaching the end of the loop, when it writes 99.
What is wrong in this seemingly simple function? I probably overlook something!?
Thanks!

int index;

private void button2_Click(object sender, EventArgs e)

{

for (index = 0; index < 100; index++)

{

textboxOut.Text = index.ToString();

Thread.Sleep(100);

}

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes12y ago
Thread.Sleep prevents the textbox from repainting until the loop completes.

However, you can force it to repaint on each iteration by inserting a call to Application.DoEvents():

for (index = 0; index < 100; index++)
{
textboxOut.Text = index.ToString();
Application.DoEvents();
Thread.Sleep(100);
}

You should now see the numbers flash by.

As a general rule, it's best to avoid Thread.Sleep in a Windows Forms application. If you want to do a countdown or similar, then use a Timer as Rahul suggested.

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Rahul12y ago
This will not work as the form will be loaded at the last once the loop completes, and that time it will show the final text. To achieve your requirement using timer, please refer the below a nice article for timer with example:
http://www.c-sharpcorner.com/UploadFile/mahesh/C-Sharp-timer/
0
Sam12y ago
Thanks, but yet:
I believe I have 100 iterations and 100 mSec delay, which yields 100 X 0.1 = 10 sec.
And in fact, it waits 10 Sec before displaying 99. (but nothing displayed before)
I still have no idea why this does not work. It is as simple as 123...
0
Rahul12y ago
No issue with code, increase the time and use this for 10 sec:
Thread.Sleep(10000);

now it will wait for 10 sec
0