Problems converting float to a string in C#

[iRead]

The value of the variable I’m trying to write to fTotal comes from a SQL query on a column with a type of float. I think my problem may have something to do with boxing and unboxing variables. I plan to research this to understand it better. Any input on what causes the errors in the two code examples below will be invaluable to my understanding of this. In each example the error rendered follows the // on the line generating the error.

Example 1:
float fTotal = 0.00F;
fTotal = (r.GetFloat(0)); //Exception Details: System.InvalidCastException: Specified cast is not valid
LTotal.Text = (fTotal.ToString());

Example 2:
float fTotal = 0.00F;
fTotal = (r.GetString(0)); //Compiler Error Message: CS0029: Cannot implicitly convert type 'string' to 'float'
LTotal.Text = (fTotal.ToString());

Thank you all for your patience and help!
iRead

 

[iRead]

Okay here is all of the code associated with the error I'm getting

The value of the variable I’m trying to write to LTotal comes from a SQL query. The firstName column is type varChar. The column amount is float. The character column writes to the variable fine. The float column causes the error in the commented line below it.

The real problem is in the code below which throws the exception I need some method any method to get that amount column to a variable.
_______________________________________________________________________
private void btnReport_Click(object sender, System.EventArgs e)
{
SqlConnection conn = new SqlConnection(ConnectionString());
SqlCommand comm = new SqlCommand("select firstName, amount from Test", conn);
comm.Connection.Open();
SqlDataReader r =
comm.ExecuteReader(CommandBehavior.CloseConnection);
while(r.Read())
{

LName.Text = (r.GetString(0));
//Exception Details: System.InvalidCastException: Specified cast is not valid.
LTotal.Text = (r.GetString(1));

}
r.Close();
conn.Close();
}
_______________________________________________________________________

Thank you all for your patience and help!
iRead

 

[obislavu]

You should write:
LTotal.Text = System.Convert.ToString(r.GetFloat(1)); // 2nd column (amount) is a float
-obislavu-

 

[iRead]

Thank you obislavu!
I had tried that and still got an error. To be truthful I tried many, many approaches with no success.

This was posted to me on another forum. This led to a resolution of the problem!

_______________________________________________________________________________

http://msdn.microsoft.com/library/d...aproviderdatatypestonetframeworkdatatypes.asp

As you can see, the .NET Framework mapping to a SQL type of float is actually "double".

handy chart to have around, I'd think!
________________________________________________________________________________

Handy to have around doesn’t cover it. Would have saved me hours!
This code works perfectly:

double dTotal = (r.GetDouble(1));
LTotal.Text = (dTotal.ToString());

Thank you!
iRead

 

[octothorpe]

float fTotal = 0.00F;
fTotal = (r.GetFloat(0)); //Exception Details: System.InvalidCastException: Specified cast is not valid

Try this instead:

double total = r.GetDouble(0);

The SQL Server float type is 64-bits, where the C# float is only 32-bits wide.

 

[octothorpe]

Oop, you beat me to it

 

[iRead]

octothorpe,
Still thank you for your input! It's right on target.
Thanks
iRead