error: input string was not a correct format

Question

private void txtdiscountallowed_TextChanged(object sender, EventArgs e) { double discount = Convert.ToDouble(txtdiscountallowed.Text); double sprice = Convert.ToDouble(txtSalesPrice.Text); double Nudiscount = sprice * discount / 100; txtCostPrice.Text = (sprice - Nudiscount).ToString(); }

Suraj Kumar · Answer

You need to use Double.TryParse method before converting textbox value to Double as it handles error and invalid cast operation. You can use below modified code. double discount; double sprice; if (Double.TryParse(txtdiscountallowed.Text, out discount)) { discount = Convert.ToDouble(txtdiscountallowed.Text); } if (Double.TryParse(txtSalesPrice.Text, out sprice)) { sprice = Convert.ToDouble(txtSalesPrice.Text); } double Nudiscount = sprice * discount / 100; txtCostPrice.Text = Convert.ToString(sprice - Nudiscount); Hope this will help you.

Jignesh Kumar · Answer

Hi Asad, Please check null before converting value, protected void txtdiscountallowed_TextChanged( object sender, EventArgs e) { double discount = ! string .IsNullOrEmpty(txtdiscountallowed.Text) ? Convert.ToDouble(txtdiscountallowed.Text) : 0; double sprice = ! string .IsNullOrEmpty(txtSalesPrice.Text) ? Convert.ToDouble(txtSalesPrice.Text) : 0; double Nudiscount; if (sprice != 0 && discount != 0) { Nudiscount = sprice * discount / 100; } else { Nudiscount = 0; } txtCostPrice.Text = Convert.ToString(sprice - Nudiscount); }