check textbox is only numbers + c#
private void textBox1_KeyPress(object sender, KeyPressEventArgs e) { // Verify that the pressed key isn't CTRL or any non-numeric digit if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) && (e.KeyChar != '.')) { e.Handled = true; } // If you want, you can allow decimal (float) numbers if ((e.KeyChar == '.') && ((sender as TextBox).Text.IndexOf('.') > -1)) { e.Handled = true; } }