Conversion problem help me

Posted Date: 19 Jun 2012 Posted By:: saravanakumar

Member Level: Gold Member Rank: 196 Points: 5 Responses: 4

Dear Sir,

con.Open();
SqlDataAdapter da = new SqlDataAdapter("select sum(stockqty) from stock where mcode='" + ddl_matcode.SelectedItem.Text.Trim() + "'", con);
DataSet ds = new DataSet();
da.Fill(ds, "table");
con.Close();

this code returns stockqty value means no problem. If is is null means the following error occur.

if (ds.Tables[0].Rows.Count == 0)
{
total_stock_qty = Convert.ToDouble(txt_matqty.Text.Trim());
}
else if (ds.Tables[0].Rows.Count != 0)
{
total_stock_qty = Convert.ToDouble(ds.Tables[0].Rows[0][0].ToString()) + Convert.ToDouble(txt_matqty.Text.Trim());
}

ds.Tables[0].Rows[0][0].ToString() this value is null means conversion error will be displayed. If you have any idea.

I have also try this,

Double.parse(ds.Tables[0].Rows[0][0].ToString())

if (ds.Tables[0].Rows[0][0].ToString() == null)
{
total_stock_qty = Convert.ToDouble(txt_matqty.Text.Trim());
}
else if (ds.Tables[0].Rows[0][0].ToString()!= null)
{
total_stock_qty = Convert.ToDouble(ds.Tables[0].Rows[0][0].ToString()) + Convert.ToDouble(txt_matqty.Text.Trim());
}

System.FormatException: Input string was not in a correct format. at System.Number.ParseDouble(String value, NumberStyles options, NumberFormatInfo numfmt) at System.Convert.ToDouble(String value) at Material.Storagelocation.bt_store_add_Click(Object sender, EventArgs e) in D:\saravanakumar\Material_grn\Material\Storagelocation.aspx.cs:line 233

please give me idea how slove this problem.

Responses

#676358 Author: Ajatshatru Upadhyay Member Level: Gold Member Rank: 17 Date: 19/Jun/2012 Rating: Points: 3
Hi, It simply means that there is no value at ds.Tables[0].Rows[0][0]. You can check this value for null before performing calculation: `If(ds.Tables[0].Rows[0][0].ToString() != String.Empty) { total_stock_qty = Convert.ToDouble(ds.Tables[0].Rows[0][0].ToString()) + Convert.ToDouble(txt_matqty.Text.Trim()); }` Hope it'll help you. Regards Ajatshatru

#676360 Author: Mahesh Durgam Member Level: Gold Member Rank: 137 Date: 19/Jun/2012 Rating: Points: 4
Hi, ToString() function will never convert 'null' values, you will get null exception. You have to use Convert.ToString() function, which has ability to convert null to empty space. Once you have converted you can compare it will empty space and then assign the value. `if (Convert.ToString(ds.Tables[0].Rows[0][0]) == "") { total_stock_qty = Convert.ToDouble(........); } else if (Convert.ToString(ds.Tables[0].Rows[0][0])!= "") { total_stock_qty = Convert.ToDouble(Convert.ToString(ds.Tables[0].Rows[0][0])) + ..... }` Thanks, Mahesh

#676363 Author: saravanakumar Member Level: Gold Member Rank: 196 Date: 19/Jun/2012 Rating: Points: 1
ya it's working fine. thank u frnd.

#676376 Author:

Anil Kumar Pandey Member Level: Platinum Member Rank: 1 Date: 20/Jun/2012 Rating: 2 out of 5

Points: 4

Try adding a NULL check as below.


if (ds.Tables[0].Rows.Count == 0)
{                           
 if(txt_matqty.Text.Trim()!="")
 {
  total_stock_qty = Convert.ToDouble(txt_matqty.Text.Trim());
  }
}
else if (ds.Tables[0].Rows.Count != 0)
{                              
 if(txt_matqty.Text.Trim()!="" && ds.Tables[0].Rows[0][0].ToString()!="" )
  {
     total_stock_qty = Convert.ToDouble(ds.Tables[0].Rows[0][0].ToString()) +      Convert.ToDouble(txt_matqty.Text.Trim());
 }
}

Thanks & Regards
Anil Kumar Pandey
Microsoft MVP, DNS MVM

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