Restrict numbers and letters in textbox - C#

Question

I want to restrict what numbers and letters can be entered into a textbox. Let\'s say I only want to allow numbers 0-5 and letters a-d (both lower and uppercase). I already tri

Answer 1

Use the KeyPress Event for your textbox.

protected void myTextBox_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs)
{
    e.Handled = !IsValidCharacter(e.KeyChar);
}

private bool IsValidCharacter(char c)
{
    bool isValid = true;

    // put your logic here to define which characters are valid
    return isValid;
}