Incorrect calculation.

Dear Experts,

I have 1 button and 4 SpinEdit-components on my form. The default
values of the 4 spinedits are: 3,9 - 4,4 - 6,7 - 8,3 in the Settings.Settings-file.
and a boolean called IsMGDL with default value false.

With this button-event below a user can switch between 2 modes:
1. If IsMGDL = true then multiple the values of the spinedits with 18.
    And the outcome has to be changed to an integer-value.
2. If IsMGDL = false then devide the values of the spinedits with 18
    And the outcome has to be changed to a double-value.

        private void btnSwUnit_Click(object sender, EventArgs e)
            Properties.Settings.Default.IsMGDL = !Properties.Settings.Default.IsMGDL;
            if (Properties.Settings.Default.IsMGDL)
                btnSwUnit.Text = "Switch to mmol/l";
                lblSwUnit.Text = "Glucose Units: mg/dl";

                int intVal1 = Convert.ToInt32(spdMinVal.EditValue) * 18;
                spdMinVal.EditValue = intVal1.ToString();
                int intVal2 = Convert.ToInt32(spdMinRng.EditValue) * 18;
                spdMinRng.EditValue = intVal2.ToString();
                int intVal3 = Convert.ToInt32(spdMaxRng.EditValue) * 18;
                spdMaxRng.EditValue = intVal3.ToString();
                int intVal4 = Convert.ToInt32(spdMaxVal.EditValue) * 18;
                spdMaxVal.EditValue = intVal4.ToString();
                btnSwUnit.Text = "Switch to mg/dl";
                lblSwUnit.Text = "Glucose Units: mmol/l";

                double doubleVal1 = Convert.ToDouble(spdMinVal.EditValue) / 18;
                spdMinVal.EditValue = doubleVal1.ToString();
                double doubleVal2 = Convert.ToDouble(spdMinRng.EditValue) / 18;
                spdMinRng.EditValue = doubleVal2.ToString();
                double doubleVal3 = Convert.ToDouble(spdMaxRng.EditValue) / 18;
                spdMaxRng.EditValue = doubleVal3.ToString();
                double doubleVal4 = Convert.ToDouble(spdMaxVal.EditValue) / 18;
                spdMaxVal.EditValue = doubleVal4.ToString();

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But when I have the 3,9 - 4,4 - 6,7 - 8,3 in the spinedits and press the button
it gives an outcome of  72, 72,126, 144 while it should be: 70, 79, 121, 149.
I don't know why this his happening!

Who knows the answer and is willing to help me?


Peter Kiers
Peter KiersOperatorAsked:
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you need to round after the multiplication instead of before
4 * 18 is 72  where as 3,9 * 72 rounded is 70

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int intVal1 = Convert.ToInt32(spdMinVal.EditValue *18);

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Peter KiersOperatorAuthor Commented:
I think you are right. I thank you for at least show me what the problem is.
Because I had no idea. But the spinedit is a component from devexpress.
so I get an error with your solution.

Operator '*' cannot be applied to operands of type 'object' and 'int'.

If you can solve it (because i don't know if its a devexpress related issue)
then tell me and I reward you the points.

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can you post the declaration for the spdMinVal control and the related using statement? or post the whole source file
Peter KiersOperatorAuthor Commented:
Peter KiersOperatorAuthor Commented:
This site doesn't allow to upload the complete zipfile so i have only
upload the Form1.cs.

I hope its enought...

Peter KiersOperatorAuthor Commented:
Be back later.

I allready give you the points.
These where yours anyway...

ok try this
int intVal1 = Convert.ToInt32(spdMinVal.Value *18);

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based on this documentation
Peter KiersOperatorAuthor Commented:
Ah, thanks it works great.
Thank you again for all the help.


Peter Kiers
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