string was in a correct format

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i have some error in code and i dont understand how to remove it.

double f,g;
string a,b;
           con.Open();
          cmd = new SqlCommand("select MAX (high) FROM DailyChange WHERE Symbol='" + Currency.SelectedValue.ToString() + "' AND Date='" + Label2.Text + "'", con);
          a = cmd.ExecuteScalar().ToString();
          f = Convert.ToDouble(a);
          Response.Write(f);
          con.Close();
          con.Open();
          cmd = new SqlCommand("select MAX (high) FROM DailyChange WHERE Symbol='" + Currency.SelectedValue.ToString() + "' AND Date='" + Label3.Text + "'", con);
          b = cmd.ExecuteScalar().ToString();

          g = Convert.ToDouble(b);
          Response.Write(g);
          con.Close();

It gives me the following error:
Input string was not in a correct format.
Line 81: g = Convert.ToDouble(b);

Posted 25-Jul-11 0:34am

saifullahiit

Updated 25-Jul-11 0:36am

Tarun.K.S

v2

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3 solutions

Solution 1

Are you sure "b" has a value that can be converted to double?

Update: There are tow problems in your code. This is how it should be IMHO:

object b = cmd.ExecuteScalar();

double result;

if((b != null) && double.TryParse(b.ToString(), out result){

// Do something with result

}
else{
// Result is either null or not a double value. Proceed accordingly
}

Posted 25-Jul-11 0:39am

dan!sh

Updated 25-Jul-11 1:04am

v2

Comments

saifullahiit 25-Jul-11 6:41am

yes

dan!sh 25-Jul-11 6:45am

What value does it have?

nareshgundapaneni 25-Jul-11 6:54am

Sure b value will be string only that is also like"abc" or "ABC" like this that's why it is giving that error man

dan!sh 25-Jul-11 7:00am

That is very much evident from the code. Still what that string value has is unclear.

Sergey Alexandrovich Kryukov 25-Jul-11 11:04am

Right, my 5.
--SA

Solution 2

Please check what are you receiving in b by debugging and make sure you are getting something like "1.3" or "1" etc. not like "abc" because this will always give you the FormatException: Input string was not in a correct fromat.

hope it helps :)

for further queries comment here!!

Posted 25-Jul-11 0:49am

Uday P.Singh

Comments

Sergey Alexandrovich Kryukov 25-Jul-11 11:05am

Right, but also, TryParse should be used as d@nish has shown. (I voted 4.)
--SA

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shefeekcm · Accepted Answer · 2011-07-25T00:54:00

Solution 3

hi,

try
{

g = Convert.ToDouble(b);
}
catch(Exception)
{
}

write the remaining code.
regards,
shefeek

Posted 25-Jul-11 0:54am

shefeekcm

Updated 25-Jul-11 0:56am

v2