convert ArrayList object to double

[Web learner]

In the following code, I want ArrayList object x to be of type double.

How can I do that?

--Thanks

SqlConnection objConnection = new
SqlConnection(" server=(local)\ \SQLEXPRESS; database=Northw ind; integrated
security=true;" );
String strSQL = "SELECT ProductName, UnitsInStock FROM Products
WHERE UnitsInStock >= 50";
SqlCommand objCommand = new SqlCommand(strS QL, objConnection);

objConnection.O pen();

ArrayList strLabel = new ArrayList();
ArrayList x = new ArrayList();

SqlDataReader dr = objCommand.Exec uteReader();

while (dr.Read())
{
object[] values1 = new object[0];
dr.GetValues(va lues1);
strLabel.Add(va lues1);

object[] values2 = new object[1];
dr.GetValues(va lues2);
x.Add(values2);
}

dr.Close();
objConnection.C lose();

[agapeton]

You need CLR 2.0 generics for that...

List<double> x = new List<double>( );

Web learner wrote:

In the following code, I want ArrayList object x to be of type double.

How can I do that?

--Thanks

SqlConnection objConnection = new
SqlConnection(" server=(local)\ \SQLEXPRESS; database=Northw ind; integrated
security=true;" );
String strSQL = "SELECT ProductName, UnitsInStock FROM Products
WHERE UnitsInStock >= 50";
SqlCommand objCommand = new SqlCommand(strS QL, objConnection);

objConnection.O pen();

ArrayList strLabel = new ArrayList();
ArrayList x = new ArrayList();

SqlDataReader dr = objCommand.Exec uteReader();

while (dr.Read())
{
object[] values1 = new object[0];
dr.GetValues(va lues1);
strLabel.Add(va lues1);

object[] values2 = new object[1];
dr.GetValues(va lues2);
x.Add(values2);
}

dr.Close();
objConnection.C lose();

[Web learner]

I changed the code as follows.

List<string> ProductName = new List<string>();
List<double> UnitsInStock = new List<double>();

SqlDataReader dr = objCommand.Exec uteReader();
while (dr.Read())
{
ProductName.Add (dr.GetValue(0) );
UnitsInStock.Ad d(dr.GetValue(1 ));
}

Now I get the following errors.

The best overloaded method match for 'System.Collect ions.Generic.Li st<string>.Add( string)' has some invalid arguments

The best overloaded method match for 'System.Collect ions.Generic.Li st<double>.Add( double)' has some invalid arguments

Any further idea, please??

--


<ag******@gmail .com> wrote in message news:11******** **************@ g10g2000cwb.goo glegroups.com.. .

You need CLR 2.0 generics for that...

List<double> x = new List<double>( );

Web learner wrote:

In the following code, I want ArrayList object x to be of type double.

How can I do that?

--Thanks

SqlConnection objConnection = new
SqlConnection(" server=(local)\ \SQLEXPRESS; database=Northw ind; integrated
security=true;" );
String strSQL = "SELECT ProductName, UnitsInStock FROM Products
WHERE UnitsInStock >= 50";
SqlCommand objCommand = new SqlCommand(strS QL, objConnection);

objConnection.O pen();

ArrayList strLabel = new ArrayList();
ArrayList x = new ArrayList();

SqlDataReader dr = objCommand.Exec uteReader();

while (dr.Read())
{
object[] values1 = new object[0];
dr.GetValues(va lues1);
strLabel.Add(va lues1);

object[] values2 = new object[1];
dr.GetValues(va lues2);
x.Add(values2);
}

dr.Close();
objConnection.C lose();

[Bruce Wood]

If you know for a fact that the first item in the data row is a string,
and the second is a double, and neither of them can ever be null, then
you can do this:

ProductName.Add ((string)dr.Get Value(0));
UnitsInStock.Ad d((double)dr.Ge tValue(1));

[carl]

The Add() methods exepct a string and double, respectively. Try this:

ProductName.Add (dr.GetString(0 ));
UnitsInStock.Ad d(dr.GetDouble( 1));

or this:

ProductName.Add ((string)dr.Get Value(0));
UnitsInStock.Ad d((double)dr.Ge tValue(1));

-Carl

[Web learner]

Will the resulting array be in following form?

double[] UnitsInStock = { 120, 104, 112, 111 };
string[] ProductName = { "Boysenberr y", "Broed", "Momo", "Taifuk" };
--The
"carl" <cz******@gmail .com> wrote in message
news:11******** **************@ i39g2000cwa.goo glegroups.com.. .

The Add() methods exepct a string and double, respectively. Try this:

ProductName.Add (dr.GetString(0 ));
UnitsInStock.Ad d(dr.GetDouble( 1));

or this:

ProductName.Add ((string)dr.Get Value(0));
UnitsInStock.Ad d((double)dr.Ge tValue(1));

-Carl

[Web learner]

For ProductName, both of the suggested methods works.

But with
UnitsInStock.Ad d(objReader.Get Double(1));
or
UnitsInStock.Ad d((double)objRe ader.GetValue(1 ));

I get the following error:

Exception Details: System.InvalidC astException: Specified cast is not valid.

"carl" <cz******@gmail .com> wrote in message news:11******** **************@ i39g2000cwa.goo glegroups.com.. .

The Add() methods exepct a string and double, respectively. Try this:

ProductName.Add (dr.GetString(0 ));
UnitsInStock.Ad d(dr.GetDouble( 1));

or this:

ProductName.Add ((string)dr.Get Value(0));
UnitsInStock.Ad d((double)dr.Ge tValue(1));

-Carl

[Jon Skeet [C# MVP]]

Web learner <be******@learn ing.edu> wrote:

For ProductName, both of the suggested methods works.

But with
UnitsInStock.Ad d(objReader.Get Double(1));
or
UnitsInStock.Ad d((double)objRe ader.GetValue(1 ));

I get the following error:

Exception Details: System.InvalidC astException: Specified cast is not valid.

Well, that suggests that column 1 isn't actually a double.

I suggest you fetch it as an object, then see what type it actually is.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[agapeton]

cast the value to the type
ProductName.Add ((string)dr.Get Value(0));

Also, you will want to follow the .NET framework coding rules. I was
rather confused at what you were doing. PascalCasing is for
Properties, MethodNames, and Types. You should make your variables
camelCased as...

List<string> productName = new List<string>();
List<double> unitsInStock = new List<double>();

this will help remove confusion in the future.

Here's a link for the guidelines...
http://msdn.microsoft.com/library/de...guidelines.asp

You will definately want to buy the book....
http://www.amazon.com/gp/product/032...lance&n=283155
the most important book you will ever buy for .NET or any development.

Let me know if you have other questions...

[Web learner]

Thanks for your helps. I have modified the code and attach it at the bottom of this message.

At line unitsInStock.Ad d((double)dr.Ge tValue(1)); I still get same error: Specified cast is not valid

If you comment out above code line and also Response.Write( unitsInStock[0]);
then the code works fine. That means it works for productName array.

My purpose is to populate an array from SqlDataReader as below:

double[] unitsInStock = { 120, 104, 112, 111 };
string[] productName = { "Boysenberr y", "Something" , "Another item", "Demo item" };
--------------------------------------------

<%@ Import Namespace="Syst em.Data" %>
<%@ Import Namespace="Syst em.Data.SqlClie nt" %>
<%@ Import Namespace="Syst em.Web.UI" %>
<%@ Import Namespace="Syst em.Collections. Generic" %>
<script language="c#" runat="server">
private void Page_Load(objec t sender, System.EventArg s e)
{
SqlConnection objConnection = new SqlConnection(" server=(local)\ \SQLEXPRESS; database=Northw ind; integrated security=true;" );
String strSQL = "SELECT productName, unitsInStock FROM Products WHERE unitsInStock >= 100";
SqlCommand objCommand = new SqlCommand(strS QL, objConnection);
objConnection.O pen();

SqlDataReader dr = objCommand.Exec uteReader();

List<string> productName = new List<string>();
List<double> unitsInStock = new List<double>();

while (dr.Read())
{
productName.Add ((string)dr.Get Value(0)); //No Error
unitsInStock.Ad d((double)dr.Ge tValue(1)); //ERROR : Specified cast is not valid
}
dr.Close();
objConnection.C lose();

Response.Write( productName[0]);
Response.Write( unitsInStock[0]);
}
</script>

<ag******@gmail .com> wrote in message news:11******** **************@ z34g2000cwc.goo glegroups.com.. .

cast the value to the type
ProductName.Add ((string)dr.Get Value(0));

Also, you will want to follow the .NET framework coding rules. I was
rather confused at what you were doing. PascalCasing is for
Properties, MethodNames, and Types. You should make your variables
camelCased as...

List<string> productName = new List<string>();
List<double> unitsInStock = new List<double>();

this will help remove confusion in the future.

Here's a link for the guidelines...
http://msdn.microsoft.com/library/de...guidelines.asp

You will definately want to buy the book....
http://www.amazon.com/gp/product/032...lance&n=283155
the most important book you will ever buy for .NET or any development.

Let me know if you have other questions...