C#

int value;
if (!(int.TryParse(myTextBox.Text, out value) && value >= 1 && value <= 100))
   {
   MessageBox.Show("Please enter a number between 1 and 100");
   ...
   return;
   }

Nathan Minier wrote:

regex are not as fast as you might think

double value;
if (!(double.TryParse(myTextBox.Text, out value) && value >= 0.1 && value <= 2.9))
   {
   MessageBox.Show("Please enter a number between 0.1 and 2.9");
   ...
   return;
   }

nicshotsize.Text = (Convert.ToInt32(totalsize.Text) - Convert.ToInt32(shortfillsize.Text)).ToString();

Damian Bz wrote:

Might as well trash this as well as any ideas of wanting to learn C#

nicshotsize.Text = (totalSize - shortFillSize).ToString();

private void totalsize_TextChanged(object sender, EventArgs e)
{
    int ts;
    if (string.IsNullOrEmpty(totalsize.Text))
        // do nothing
        ;
    else
    {
        if ((totalsize.Text.All(chr => char.IsLetter(chr))) | (totalsize.Text.Contains(".")))
        {
            MessageBox.Show("Please enter only whole numbers between 1 and 500");
            totalsize.Clear();
            totalsize.Focus();
        }
        else
        {
            ts = Convert.ToInt32(totalsize.Text);

            if (!(ts >= 1 && ts <= 500))
            {
                MessageBox.Show("Please enter only whole numbers between 1 and 500");
                totalsize.Clear();
                totalsize.Focus();
            }
        }

    }
}

private void totalsize_Leave(object sender, EventArgs e)
{
    if (!string.IsNullOrEmpty(totalsize.Text) && !string.IsNullOrEmpty(shortfillsize.Text))
        nicshotsize.Text = (Convert.ToInt32(totalsize.Text) - Convert.ToInt32(shortfillsize.Text)).ToString();
    if (!string.IsNullOrEmpty(totalsize.Text))
        totalsizenum = Convert.ToDouble(totalsize.Text);

}

Textbox.Text = Math.Round(Textboxtmp, 2).ToString();

// Boolean flag used to determine when a character other than a number is entered. 
        private bool nonNumberEntered = false;

        // Handle the KeyDown event to determine the type of character entered into the control. 
        private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
        {
            // Initialize the flag to false.
            nonNumberEntered = false;

            // Determine whether the keystroke is a number from the top of the keyboard. 
            if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
            {
                // Determine whether the keystroke is a number from the keypad. 
                if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
                {
                    // Determine whether the keystroke is a backspace. 
                    if(e.KeyCode != Keys.Back)
                    {
                        // A non-numerical keystroke was pressed. 
                        // Set the flag to true and evaluate in KeyPress event.
                        nonNumberEntered = true;
                    }
                }
            }
            //If shift key was pressed, it's not a number. 
            if (Control.ModifierKeys == Keys.Shift) {
                nonNumberEntered = true;
            }
        }

        // This event occurs after the KeyDown event and can be used to prevent 
        // characters from entering the control. 
        private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
        {
            // Check for the flag being set in the KeyDown event. 
            if (nonNumberEntered == true)
            {
                // Stop the character from being entered into the control since it is non-numerical.
                e.Handled = true;
            }
        }

void textBoxSample_KeyPress(object sender, KeyPressEventArgs e)
    {
        e.Handled = Char.IsPunctuation(e.KeyChar) ||  
                      Char.IsSeparator(e.KeyChar) || 
                      Char.IsSymbol(e.KeyChar);
    }

private void nicstrength_KeyPress(object sender, KeyPressEventArgs e)
{
    e.Handled = Char.IsSeparator(e.KeyChar) || Char.IsSymbol(e.KeyChar); //|| Char.IsPunctuation(e.KeyChar);

}

private void nicstrength_TextChanged(object sender, EventArgs e)
{
    double ns;
    if (string.IsNullOrEmpty(nicstrength.Text))
        // do nothing
        ;
    else
    {
        if ((nicstrength.Text.Any(chr => char.IsLetter(chr))) || (nicstrength.Text.StartsWith(".")))


        {
            MessageBox.Show("Please enter a number between 1 and 10 inc decimal points i.e 7.2");
            nicstrength.Clear();
            nicstrength.Focus();
        }
        else
        {
            ns = Convert.ToDouble(nicstrength.Text);

            if (!(ns >= 1 && ns <= 10))
            {
                MessageBox.Show("Please enter a number between 1 and 10 inc decimal points i.e 7.2");
                nicstrength.Clear();
                nicstrength.Focus();
            }
        }

    }
}

private readonly char[] notallowed = { '!', '"', '#', '%', '&', '\'', '(', ')', '*', ',', '-', '/', ':', ';', '?', '@', '[', '\\', ']', '_', '{', '}', '+' };

if ((nicstrength.Text.Any(chr => char.IsLetter(chr))) || (nicstrength.Text.StartsWith(".")) || (nicstrength.Text.IndexOfAny(notallowed) != -1))