c# increasing numericUpDown1 by increments of 25 and nothing else-CodePudding

I am trying to set the numericUpDown1 so it will only increase by increments of 25. I only want the numbers to increase by 25 and not allow other things. so for example I want 25, 50 75, 100. I don't want any other number lets say 26,51,76,101 also is increments of 25 but I dont want that. I just want increments that are able to divide by 25 basically.

CodePudding user response：

Set your NumericUpDown's Increment property to 25, then double click on it in the designer and put a ValueChanged event handler that constrains the input to a multiple of 25:

    private void numericUpDown1_ValueChanged(object sender, EventArgs e)
    {
        if (numericUpDown1.Value % 25 == 0) return;
        numericUpDown1.Value = Math.Round(numericUpDown1.Value / 25) * 25;
    }

The first line that checks % isn't strictly necessary and can be removed if you're happy to rely on an NUD not raising a ValueChanged event if it is set to the same value that is currently displaying.

The flow of the code is:

user types e.g. 7 into the box. ValueChanged fires.
7% is not 0
the code rounds 7 down to 0 and sets the Value to 0.
ValueChanged fires again (because we just changed the value)
0%0 is 0, the code returns from the second fire
the code returns from the first fire

If you remove the mod check the code still returns because:

user types e.g. 7 into the box. ValueChanged fires.
the code rounds 7 down to 0 and sets the Value to 0.
ValueChanged fires again (because we just changed the value)
the code rounds 0 down to 0 and sets the Value to 0
0 is not a change in value so the event does not raise again
the code returns from the second fire
the code returns from the first fire

I've always preferred to put something in that I can see stops infinite firing if I change a control programmatically, but your preferences may differ