private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
if (("0123456789".IndexOf(e.KeyChar.ToString()) == -1) && e.KeyChar != (char)8) e.Handled = true;
else e.Handled = false;
}
{
if (("0123456789".IndexOf(e.KeyChar.ToString()) == -1) && e.KeyChar != (char)8) e.Handled = true;
else e.Handled = false;
}
{
if ( (Char.IsLetter(e.KeyChar) || Char.IsPunctuation(e.KeyChar) && !e.KeyChar.Equals('.') || Char.IsSeparator(e.KeyChar)) && !e.KeyChar.Equals('-') || e.KeyChar.Equals('+') || e.KeyChar.Equals('='))
e.Handled = true;
else
{
e.Handled = false;
}
}