Question

I am currently building my project using windows forms and came across a minor “problem”.

I have the user enter an hour which is stored as an int. I want to provide detailed feedback to the user so that they know exactly what they have done wrong should they cause an error.

If no value is given, a format exception is thrown.
If anything but an integer is given, a format exception is thrown.

This means I cannot directly tell the user that the new item could not be added due to EITHER 1) no value or 2) not an integer as they both use the same exception.

How can I solve this and what would be the best solution?

Many thanks.

Answer 1

some example code related to your question; note ValidateData in particular:

// called from ok button click or similar event
private void Accept()
{
   if (!ValidateData())
      return;

   SaveData();
   DialogResult = DialogResult.Ok;
   Dispose();
}

private bool ValidateData()
{
   int val;

   if (string.IsNullOrEmpty(mTextBox.Text))
      return FailValidation("Value can not be empty.", mTextBox);

   if (!int.TryParse(mTextBox.Text, out val))
       return FailValidation("Value was not an integer.", mTextBox);

   return true;
}

// do something with the value if you need
private void SaveData()
{       
}

// post a message to the user, and highlight the problematic control
// always evaluates to false
private bool FailValidation(string pMessage, Control pControl)
{
     if (pControl != null)
     {
        pControl.Focus();
        TextBox textBox = pControl as TextBox;
        if (textBox != null)
           textBox.SelectAll();
     }

     AlertBox(pMessage);
     return false;
}

// quick alert message method
private void AlertBox(string pMessage)
{
   return MessageBox.Show
   (
      pMessage,          
      Application.ProductName,
      MessageBoxButtons.OK,
      MessageBoxIcon.Exclamation,
      MessageBoxDefaultButton.Button1
   );
}