C#. How to use pass multiple text boxes into method and automatically refresh label

Question

my first post here.

I'm building a calculator that takes user input via text box and converts to a double and passes those numbers into a custom class that contains a formula(the answer is converted back to a string once complete). I have everything working, but I would like the label with the answer to automatically update once the text boxes are filled out. The label text output is correct once clicked on.

heres the code I have for the label so far...

    private void lblUtil1_Click(object sender, EventArgs e)
    {

        dblUtil1 = Tinseth.Bigness(dblSG) * Tinseth.BTFactor(dblBT1);
        double UtilRounded1 = Math.Round(dblUtil1 * 100);
        lblUtil1.Text = UtilRounded1.ToString() + "%";
    }

Is there something that can detect if all the pertinent fields are completed or will this require a loop? I greatly appreciate all help and look forward to being a part of this community!

growthtek

score 1 · Answer 1 · answered Nov 17 '13 at 02:55

One approach would be to make this:

private void lblUtil1_Click(object sender, EventArgs e)
{
    dblUtil1 = Tinseth.Bigness(dblSG) * Tinseth.BTFactor(dblBT1);
    double UtilRounded1 = Math.Round(dblUtil1 * 100);
    lblUtil1.Text = UtilRounded1.ToString() + "%";
}

a shared method:

private void Calculate();
{
    dblUtil1 = Tinseth.Bigness(dblSG) * Tinseth.BTFactor(dblBT1);
    double UtilRounded1 = Math.Round(dblUtil1 * 100);
    lblUtil1.Text = UtilRounded1.ToString() + "%";
}

and get rid of the Click event. Then consume the text boxes Validated event:

private void TextBox_Validated(object sender, EventArgs e)
{
    Calculate();
}

Now hook all of the text boxes Validated events up to this same handler. Now when the user leaves the text box, it will calculate automatically.

The Validated event could just as easily be the TextChanged event as well. That will calculate every time they type a number. But that's probably too frequent.

How would I get rid of the click event without triggering an error in windows forms? Should I create a different class for the calculation? I also have to pass 9 different sets of variables through this calculation. This is my first windows forms project and I really appreciate the help! — growthtek, Nov 17 '13 at 03:16
@growthtek, you don't need the click event anymore to do the calculations. Just hook up the text boxes and let them call `Calculate`. Now, as far as the issue with the compiler, which is what I'm guessing you're talking about, just find the line of code that hooked up that old event handler. It should look like this: `+= lblUtil1_Click`; or something close to that. — Mike Perrenoud, Nov 17 '13 at 03:18

score 0 · Answer 2 · answered Nov 17 '13 at 02:49

0

Create one function that does the calculation then bind that function to the changed event on all the textboxes.

answered Nov 17 '13 at 02:49

Measurity

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How would I bind it to the text box? Theres already a method handling the main calculations as well. – growthtek Nov 17 '13 at 03:08
with textBox.TextChanged += YOUR_METHOD where the method does all the textbox input retrieving and outputting to the result textbox. – Measurity Nov 17 '13 at 03:11

score 0 · Answer 3 · answered Nov 18 '13 at 05:16

I would not run the calculation every time as Michael or Measuring suggested.

Instead, just put a few if statements in your click event that test to see if the required boxes have values. If they don't, then show a message saying they need to fill it out.

Something like:

if (String.IsNullOrEmpty(TextBox1.Text)) {
    MessageBox.Show("TextBox1 is empty");
    return;
}

C#. How to use pass multiple text boxes into method and automatically refresh label

3 Answers3

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