Exception on a simple string conversion

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1.00/5 (1 vote)

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Not sure what is going on here.
I get an exception on the conversion of the string to int.

using System;
using System.Windows.Forms;

namespace WinFormsApp4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            int anInteger = Convert.ToInt32(textBox1.Text);
            label1.Text = anInteger.ToString();
        }
    }
}

Is me or my Visual Studio is crazy?!

Posted 22-Dec-13 2:46am

Millone

Updated 22-Dec-13 2:59am

v2

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Er. Tushar Srivastava 22-Dec-13 8:54am

Is there any text inside the textbox when the application is loaded?

Millone 22-Dec-13 8:57am

no. It is empty but even if I set the text box ="1"; I get the same problem.

Er. Tushar Srivastava 22-Dec-13 9:01am

Try to do this, add a form load event and shift this statement to that part I guess that will solve the issue. BTW, i am no expert in this... yet, try it please :)

Pheonyx 22-Dec-13 8:55am

Okay, well the first question is what exception are you getting? You've not told use that.
The next question, is why on earth are you converting a string to make it a string again it seems like a bit of wasted time?

Millone 22-Dec-13 8:58am

Format exception not managed on this line int anInteger = Convert.ToInt32(textBox1.Text);

Pheonyx 22-Dec-13 9:03am

Put a try catch block around that code and find out the details of that exception. Have you used the debugger to go through that and confirm that textBox1.Text has the values your are expecting?

Millone 22-Dec-13 9:06am

Yes but does not make sense to me. Why I am getting the error, this is the problem!

Pheonyx 22-Dec-13 9:13am

You say this is a simple representation of the problem. It makes me thing there is more too it, because I just wrote the same code in a brand new project and it worked with no issues.
Are you doing anything prior that might be causing the issue?
Is that message "Format Exception not managed" the full error text that occurs? If you look at the actual exception object, is there an inner exception or more details in it?

Millone 22-Dec-13 9:17am

Thats all in the project. I experienced the problem in a much more complex context and I reproduced it in a project where the code is all pasted in my question. I made it on purpose to make sure there was nothing else involved. There is nothing else in such project. I suspect I have a problem with my visual studio.

Millone 22-Dec-13 9:04am

It is just a sample representing the problem.

BillWoodruff 22-Dec-13 10:35am

Anytime you have a confusing error, like this one, use the debugger to inspect the contents of variables.

In this case: put a breakpoint on the line:

int anInteger = Convert.ToInt32(textBox1.Text);

and examine the value of textBox1.Text.

I predict that if you do that, you'll understand what's going on.

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OriginalGriff · Answer 1 · 2013-12-22T03:49:00

Firstly, don't use Convert.ToInt32 - use the TryParse method instead:

C#

int myInt = 0;
if (!int.TryParse(textBox1.Text, out myInt))
   {
   MessageBox.Show("Please enter a number!");
   return;
   }
label1.Text = myInt.ToString();

It returns true if the conversion succeeded, and false if it didn't.

But... there is a slightly deeper problem.
Why are you doing this in the constructor? The value is whatever you set at desgin time, so you really shouldn't need to read it yet...