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Hello;

I'm using NumericUpDown control on a windows form, when executing, pressing Delete key or Backspace key make the field empty.

how can i reset the value to its minimum value when this situation occurs ?
thank you
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[no name] 20-Sep-14 16:21pm    
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.onkeyup(v=vs.110).aspx
Abinonos 20-Sep-14 16:45pm    
That do not work ! i already tried with both keyDown and KeyUp Events.
(the underlaying text boxt is cleared and do not show the value even set to 0)
[no name] 20-Sep-14 17:10pm    
Well considering that we cannot see your code and you have not described an actual problem, what is it that you expect from us?
Sergey Alexandrovich Kryukov 20-Sep-14 22:01pm    
Well, frankly, the problem is pretty clearly defined. And this is a pretty delicate question, even though it is based on incomplete observation of the behavior. Please see my answer.
—SA
[no name] 21-Sep-14 8:09am    
If you can see a "clearly defined" problem in "That do not work" then more power to you. The rest of it is just plain nonsensical gibberish.

If your goal is to make sure the NumericUpDown Control is reset to its minimum value if the value-entry-field is empty, and the NumericUpDown Control loses Focus:
C#
private void numericUpDown1_Leave(object sender, EventArgs e)
{
    if (numericUpDown1.Text == String.Empty)
    {
        numericUpDown1.Value = numericUpDown1.Minimum;
        numericUpDown1.Text = numericUpDown1.Value.ToString();
    }
}
Handling backspace and delete, and detecting when the value-entry field is empty can be done:
C#
private void numericUpDown1_KeyUp(object sender, KeyEventArgs e)
{
    if (numericUpDown1.Text == String.Empty)
    {
        numericUpDown1.Value = numericUpDown1.Minimum;
        numericUpDown1.Text = numericUpDown1.Value.ToString();
    }
}
However, using the second code example creates an "awkward" behavior: when the minimum value is reset, and its Text representation reset, the cursor will insist on going to the start-position in the edit field (no way to move that cursor that I know of in C#). If I want to edit "beyond" first digit of the number, I've got to manually shift the cursor position.

And, assume you set the minimum value to #40, and then you want to edit that and change it to #80; if you are using the second code example, if you clear the value-entry-field, it will reset to #40 again, so you've got to do a little dance with moving the insertion cursor and selecting/or deleting the first digit only.

Depending on the person, given you can use the arrow-keys to move the insertion point, this "price" you pay with code example 2 may be okay, or not okay.

The NumericUpDown Control, like many of the MS supplied Controls, has its quirks, and limits. The requirement ... as you can see in both code examples above ... to have to re-draw the Text in the value-entry-field after we've successfully set the Value in code is rather stupid (and there is no combination of Update/Refresh/Invalidate that I've found that can remove that requirement).
 
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Abinonos 21-Sep-14 8:57am    
You solution is working good, thank you.
Sergey Alexandrovich Kryukov 21-Sep-14 12:21pm    
Voted 4.

I have some notes. Even though everyone usually can guess that numericUpDown1_Leave and numericUpDown1_KeyUp are uses as handlers of the events Leave and KeyUp, it is not written anywhere. Moreover, we saw cases when such names exist but don't work because adding the handlers to invocation lists of the event instances was removed, but auto-generate code remained. This is just the bad practice.
It's better to show the code with '+=' or at least explain what is it. I even never add even handlers using the designer and advice to never do so, be a number of reasons, but this advice can be a matter of discussion or criticism.

Besides, it's not good to set a sample of bad coding for the readers, especially the beginners. Such auto-generated names, as well as numericUpDown1, violate (good) Microsoft naming convention. They are auto-generated (the designer cannot do better because "it doesn't know" intended semantics) are not designed for permanent use and should be renamed after they put to use. What is the refactoring engine for?

There is another problem: second line in the handlers, assignment of the result of ToString. First, I think it's redundant; the assignment to the value will assign the string (you can check it up). Worse, such string assignment bypasses the string assignment already code in the original control and thus break its intended formatting.

And finally, I am still not convinced that the default behavior of the control is not good enough. Please see Solution 1.

—SA
The control actually already behaves pretty reasonably. You are missing one important detail: when you type anything on the control, its property Value is not actually modified. Non-digits are filtered out, but you can use Del or Backspace and actually make the text input empty. Another detail you are missing is: likewise, you can actually type too many digits to type the number above the value of the Maximum. It can be even the string which would fail to parse as a value numeric value. Still, nothing bad happens: Value is not yet modified.

It is actually modified when you press Enter or the control looses focus. At that time, some valid value is written in the control and the property Value is modified accordingly.

I tried to think about modification of the text while one edits it in a control (mostly, for TextBox) and came to the conclusion: filtering out some input is perfectly fine, but any modifications of the entering code is evil. It can only confuse the user (and maybe even yourself). If there is a way to type wrong string in a control, the user should be allowed to do so. Typing data should not be considered as entering data. The actual numeric value should be determined (and visually updated) later, after the user do something indicating the end of input and before the actual use of the data. Which is the case for NumericUpDown.

—SA
 
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Abinonos 21-Sep-14 9:00am    
thank you for explanations, let me add something else :
when typing Delete key, the keyDown and KeyUp events occur and both are treated internally, so the textual representation will have a missing digit at the left side :
-keyDown reset the value to zero as does BillWoodRuff.
-KeyUp deletes the extreme left digit.

I'm Now trying to accomodate my code with that .
Sergey Alexandrovich Kryukov 21-Sep-14 12:08pm    
Good point...
—SA
Thank you for your answers , Bill, Sergey;
I'm trying your advices and solutions and will comment that soon.

As i will use the NumericUpDown control many times, i will even consider iheriting from the raw one to implement any eventual solution.
Thank you
 
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Sergey Alexandrovich Kryukov 21-Sep-14 12:12pm    
You are welcome.
But please, don't post content like that as "Solution". It is not, and such posts don't belong here, considered as abuse.
And nobody receives notification. So, instead, use comments and/or "Improve question". A comment on a post generates notifications sent to the authors of the posts between your comment and a root of the post tree.

Thank you for understanding.
—SA

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