How to trap key press to accept only numeric keys

  Hello word.  Lets talk about trapping keys.  For example I have a TextBox name tbStudentId and this is where the user enters a student's ID number.  Now, you want it to accepts numbers but not letters.  How can we do that?

Try this line of code:

Public Class Form1

    Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress

        e.Handled = allownumeric(e.KeyChar)

    End Sub

    Public Function allownumeric(ByVal key As String) As Boolean

        Dim numbers As String = "0123456789"

        If key <> Chr(8) Then

            If numbers.Contains(key) Then

                allownumeric = False

            Else

                allownumeric = True

            End If

        End If

    End Function

End Class

   What doees Chr(8) mean? It's the backspace.  Your text box must also include backspace to allow changes in input.

   You may download the program here.