C# Calculating textbox values?

[Joni_78]

Hi,

I have an application with 20 textboxes, i need to do the calculations for example ((TextBox12 * TextBox1 * TextBox7) / 2) and display the result on label when clicking a button.

Ive usually done these like this:

private void lBtn_Click(object sender, EventArgs e)
		{
			double L, L2;
			if (double.TryParse(kTb1.Text, out L) && double.TryParse(kTb2.Text, out L2))
				lBl4.Text = String.Format("{0:f1}", (L2 * L));
			else
				MessageBox.Show("WTF?");
		}
[/CODE]

I was wondering if there is better way to do this so that I don't have to add all 20 textboxes into this with && double.TryParse?

[+Majesticmerc MVC]

You could add the text boxes into an array, and then iterate over the array...

private void lBtn_Click(object sender, EventArgs e) {
	TextBox[] textboxes = {
		kTb1,
		kTb2,
		kTb3,
		...
		kTb20
	};

	double temp = 0D, total = 0D;
	bool isError = false;
	foreach (TextBox tb in textboxes)
	{
		if (!double.TryParse(tb.Text, out temp))
		{
			isError = true;
			break;
		}

		total *= temp
	}

	if (isError)
		MessageBox.Show("WTF?");
	else
	   lBl4.Text = String.Format("{0:f1}", total);
}
[/CODE]

To generate the array, you could create it in the form's constructor (or OnLoad event handler), and store it as a class variable...

[CODE]
TextBox[] m_textboxes;

protected void Form1_Load(Object sender, EventArgs e)
{
TextBox[] m_textboxes = {
kTb1,
kTb2,
kTb3,
...
kTb20
};
}
[/CODE]

If the only text boxes on the form are the ones you'll be using in the calculation, you could also use the Controls property to get the list of child text boxes :)

[Kami-]

I'd put the textboxes into a panel, iterate the panels controls where the type is a textbox, load the value into an object then use the object to output your requirements.

[articuno1au]

I agree with the panel part, but after that you may as well operate out of the boxes.

[Aethec]

The point of a TextBox is to allow the user to enter text, not numbers.

If you want the user to enter numbers, use NumericUpDowns instead. It'll be much simpler since you are sure they contain numbers :)

[articuno1au]

Depends on whether he needs doubles or not. Numeric up downs are a pain in the ass with decimals of a sufficient length.

[+Majesticmerc MVC]

  On 12/06/2012 at 12:26, mute~ said:

I'd put the textboxes into a panel, iterate the panels controls where the type is a textbox, load the value into an object then use the object to output your requirements.

Agreed that this is the best way to go.

[Andre S. Veteran]

An application with 20 textboxes sounds like a pain in the ass to begin with. That said, you can at least factor out repetitive code inside methods, for instance you could create an extension method for textboxes to get their value as a double:

public static double getValue(this TextBox txtBox) {
	 return double.Parse(txtBox.Text;)
}
[/CODE]

So your code can look like:

[CODE]
try {
lbl4.Text = string.Format("{0:f0}", txt1.getValue() * txt2.getValue() / 3);
}
catch (Exception) {
MessageBox.Show("WTF?");
}
[/CODE]

Btw double.Parse with a try-catch (rather than TryParse) is probably the best approach here, it's not like the cost of throwing an exception in this case was of any significance and it leads to cleaner code.

[+Majesticmerc MVC]

  On 12/06/2012 at 15:47, Dr_Asik said:

An application with 20 textboxes sound like a pain in the ass to begin with. That said, you can at least factor out repetitive code inside methods, for instance you could create an extension method for textboxes to get their value as a double:

<snip>
[/CODE]

Btw double.Parse with a try-catch (rather than TryParse) is probably the best approach here, it's not like the cost of throwing an exception in this case was of any significance and it leads to cleaner code.

How does what you did eliminate repetitive code versus simply using a loop? Using an extension method seems a bit overkill.

[Andre S. Veteran]

  On 12/06/2012 at 15:55, Majesticmerc said:

How does what you did eliminate repetitive code versus simply using a loop? Using an extension method seems a bit overkill.

Assuming he's doing some operation that involves getting the values of all textboxes indistinctly (like a sum or an average), a loop is the obvious solution, but from his code example I gathered he wants to do operations involving specific textboxes and is wondering how to avoid having to write the double.TryParse boilerplate every time. Maybe I just misinterpreted though, anyway the loop solution was already given by others here.

[+Majesticmerc MVC]

  On 12/06/2012 at 15:59, Dr_Asik said:

Assuming he's doing some operation that involves getting the values of all textboxes indistinctly (like a sum or an average), a loop is the obvious solution, but from his code example I gathered he wants to do operations involving specific textboxes and is wondering how to avoid having to write the double.TryParse boilerplate every time. Maybe I just misinterpreted though, anyway the loop solution was already given by others here.

Actually yeah I see your point now; the first code snippet in the OP seems to suggest arbitrary calculations while the later code snippets suggest otherwise. Interesting.

[Joni_78]

Actually there will be about 50 textboxes, user inputs value 1-5 and I need to make three calculations from specific textboxes.

[ShiZZa]

I don't recommend looping at all. All values should be read into local vars. Looping is to much magic. Ya looks cool because you wrote like 10 lines of code. But if someone else has to look at it they will call you idiot.

[Joni_78]

I wonder if the textboxes are the right way to do this afterall?

This application will have 50 textboxes and user inputs values 1-5. Two buttons, calculate and clear. After the calculations it shows a the results of 8 calculations and also a graph.

I first thought I do it with popup dialog but then decided to use textboxes so that user can check the entered values but it will have alot of textboxes...

Any ideas?

[Andre S. Veteran]

  On 14/06/2012 at 07:31, Joni_78 said:

I wonder if the textboxes are the right way to do this afterall? This application will have 50 textboxes and user inputs values 1-5. Two buttons, calculate and clear. After the calculations it shows a the results of 8 calculations and also a graph. I first thought I do it with popup dialog but then decided to use textboxes so that user can check the entered values but it will have alot of textboxes... Any ideas?

So the user has 5 values to enter and you want to display the result of 8 calculations. Why do you need 50 different fields for that?

I'm not too familiar with Winforms but if you have a lot of data it's usually better to display it with some kind of list control, perhaps DataGrid or ListView.

[Joni_78]

  On 14/06/2012 at 13:38, Dr_Asik said:

So the user has 5 values to enter and you want to display the result of 8 calculations. Why do you need 50 different fields for that?

I'm not too familiar with Winforms but if you have a lot of data it's usually better to display it with some kind of list control, perhaps DataGrid or ListView.

I meant user needs to enter value 1-5 for every textbox.

[Andre S. Veteran]

Ok so you have 8 different calculations that all require 5 inputs for the user and a field to display the result, if I understand correctly. So you could design a UserControl that has 5 input fields and a result field, and use that 8 times with a different equation passed in as a parameter. The equation could be a five-argument Func where the arguments are the 5 different textbox values. Does that make any sense for you?

[+FloatingFatMan Subscriber¹]

Use a datagridview, like Dr_Asik suggests. It'll be way easier, less confusing to the user, and lighter on resources, than filling a form with 50 textboxes and their labels.