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error: input string was not a correct format

error: input string was not a correct format

Asad khan

8y1.3kVisual Basic .NET

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();

}

2 Replies

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Suraj Kumar8y ago
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.
+1
Jignesh Kumar8y ago
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);
       }
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