Looping through textboxes in C#

[leader2k]

High i did run a search in the forum so not to be redundant.
i have about 10 textboxes to loop through.and i don't want to use the same function again and again so here is mycode below,it would appreciated if
somebody help me with it
" private void button1_Click(object sender, EventArgs e)
{
int values = Convert.ToInt32(textBox1.Text);
if (values % 2 == 0)
{
textBox1.BackColor=Color.Green;
}
"
My regards

[TheGreatCthulhu]

Add a private field of type List<TextBox>, e.g.:
private List<TextBox> textboxes = new List<TextBox>();
Then fill the list in the constructor or in the Load event handler, so that it holds all of your textboxes.

Then in your button click handler, you can do:

textboxes.Where(tb => Convert.ToInt32(tb.Text) % 2 == 0).ToList()
.ForEach(tb => tb.BackColor = Color.Green);

[leader2k]

First of all i immensely appreciate your reply,which i did apply for some reason is not working ,obviously i'm doing something wrong.All i want is to loop through 10 textboxes or so,and if the value it's odd,tb colored in a color and if it's even another color.
My regards

[TheGreatCthulhu]

Well, can you post some code, and maybe compiler error messages (if there are any), so that we can see what's wrong?

P.S. When posting code, you can use the [code][/code] tags to preserve formatting. (If the code is not already formatted, it will not format it - it only preserves existing formatting.)

[leader2k]

HI
Thank you for the help in advance ,the code is below,and it's not working
Myregards

       }
        List<int> myList = new List<int>();
    
             TextBox[] textBoxes = { textBox1, textBox2, textBox3, textBox4 };
             for (int i = 0; i < textBoxes.Length; i++)
             {

              private void button1_Click(object sender, EventArgs e)
        {
    
            textboxes.Where(textBox=> Convert.ToInt32(textBox.Text) % 2 == 0).ToList()
                  .ForEach(textBox => textBox.BackColor = Color.Green);
        }
    }
}

[Arjay]

No need to create a separate array as the form already contains a list of controls. All you need to do is extract the TextBox controls from the other controls.

private void button1_Click(object sender, EventArgs e)
{
  foreach (var textbox in Controls.Cast<object>()
      .Select(control => control as TextBox)
      .Where(textbox => textbox != null))
  {
    if (Convert.ToInt32(textbox.Text) % 2 == 0)
    {
      textbox.BackColor = Color.Green;
    }
  }
}

[TheGreatCthulhu]

^Yes, that's a better, more flexible, solution.
EDIT: But be careful if you want to select only a subset of the textboxes, you'll need some way to filter them.

[Arjay]

^Yes, that's a better, more flexible, solution.
EDIT: But be careful if you want to select only a subset of the textboxes, you'll need some way to filter them.

What I posted is okay for a student type solution, but for production code, I'd recommend going to something like an MVVM pattern (where the model binds to behaviors of the controls) rather than manipulating the controls directly.

[leader2k]

Hi Guys
Thank you very much the last one did it, No quite .
Sorry this error was thrown all of sudden (An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll)
help highly appreciated
My regards

[Arjay]

Hi Guys
Thank you very much the last one did it, No quite .
Sorry this error was thrown all of sudden (An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll)
help highly appreciated
My regards

When you post to the forum, please include the exact code and the line that an error occurs. Posting back that some snippet of code that you were given doesn't work isn't very helpful.

[leader2k]

Hi
// if (Convert.ToInt32(textbox.Text) % 2 == 0) Here Where the error was thrown.and by the way i didn't change anything in the code cause i'm testing it as a stand alone.
Thank you
My regards

[Arjay]

Hi
// if (Convert.ToInt32(textbox.Text) % 2 == 0) Here Where the error was thrown.and by the way i didn't change anything in the code cause i'm testing it as a stand alone.
Thank you
My regards

You need to understand that you are trying to convert a string into an integer and a requirement of this is whatever the string value is must be convertible. That means all text boxes need to have valid numeric values. If any of the textboxes are blank or don't contain a valid numeric value, you'll get an exception.

Good code needs to handle these types of user situations. One way to validate that is each textbox contains a valid numeric value is to use Int32.TryParse.

private void button1_Click(object sender, EventArgs e)
{
  foreach (var textbox in Controls.Cast<object>()
      .Select(control => control as TextBox)
      .Where(textbox => textbox != null))
  {
    var value = 0;

    if(Int32.TryParse(textbox.Text, out value))
    {
      if (value % 2 == 0)
      {
        textbox.BackColor = Color.Green;
      }
    }
    else
    {
       // TODO: display invalid textbox value
    }
  }
}

[leader2k]

Hi
you Nailed it.
Thank you immensely for the help
My regards

[greenharry419]

Thanks for replying with the complete code.