Numeric TextBox

Question

Im new to programming and I dont know very much about but I\'m making a calculator, and i want to use a textbox that only acepts numbers and decimals, and when the user past

Answer 1

Add an event handler for the textbox you want to be numeric only, and add the following code:

private void textBoxNumbersOnly_KeyPress(object sender, KeyPressEventArgs e)
{
   if (Char.IsDigit(e.KeyChar) || e.KeyChar == '\b')
   {
      e.Handled = false;
   }
   else
   {
      e.Handled = true;
   }
}

This allows for numbers 0 to 9, and also backspaces (useful IMHO). Allow through the '.' character if you want to support decimals

Answer 2

There is a control in the framework which is specially made for numeric input : the NumericUpDown control. It also manages decimal values.

Answer 3

here how to do this in vb.net

Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
    Dim reg As New System.Text.RegularExpressions.Regex("[^0-9_ ]")
    TextBox1.Text = reg.Replace(TextBox1.Text, "")
End Sub

just fix the regex for your specific needs

Answer 4

Being a novice you might be better off investing in a good third party toolkit. Radcontrols from Telerik for instance has a numeric textbox that will accomplish what you are looking for.

Answer 5

        if ("1234567890".IndexOf(e.KeyChar.ToString()) > 0)
        {
            e.Handled = false;
        }
        else
        {
            e.Handled = true;
        }

Answer 6

i would probably use a regular expression to screen out non-numerics.

pseudo code:

for (each item in the input string) {
   if (!match(some regular expression, item)) {
        toss it out
   } else {
        add item to text box or whatever you were going to do with it
   }

}