Re: a couple of C# questions - C# Discussion Boards

24-Oct-05 23:05

Hi,

I just have a couple of questions:

If I have the following, what is the value of decEuro if the textbox txtEuro is empty? decimal decEuro = Convert.ToDecimal(txtEuro.Text.Trim());

Is decimal the best data type used for a currency value?

/********************************************************/

Check the following function:

public static Object CheckDecimalForDB(decimal decCheckDecimal)
{
if(decCheckDecimal != 0)
return decCheckDecimal;
else
return DBNull.Value;
}

The datatype/type returned when decCheckDecimal contains a value, is decimal, or Object?

/********************************************************/

I need to format data in a data grid, firstly time based on Culture info (South Africa), and secondly, decimal values to contain only 2 decimal places after the comma.

This is how I populate my datagrid with the 2 values:

<asp:Label id="lblDateRequested" Text='<%# DataBinder.Eval(Container.DataItem, "DateRequested", "{0 Big Grin | :-D

}") %>' runat="server" />

<asp:Label id="lblAgencyID" Text='<%# DataBinder.Eval(Container.DataItem, "Euro") %>' runat="server" />

"DateRequested" has a datetime datatype in SQL Server, and "Euro" is of type money.

/********************************************************/

I need to post data from one form to another form. I used Server.Transfer but then the new page doesn't display in the url "bar". Basically I just want the data to go from page A to page B. Usually in classic ASP I used Request.Form("txtFName") to get the value of the textbox in page A. I'm not sure if the Response.Redirect method does this, don't think so.

This is all for now, I hope to here from the experts soon.

Regards.
ma se Cool | :cool:

Rob Philpott24-Oct-05 23:52

24-Oct-05 23:52

Surely if you are unsure of stuff like this, the best thing to do is create a simple console application and try it out?

decimal decEuro = Convert.ToDecimal(txtEuro.Text.Trim());

If the textbox is empty, you'll be trying to convert an empty string to a decimal, and an exception will be thrown so it'll never get as far as assigning decEuro.

public static Object CheckDecimalForDB(decimal decCheckDecimal)
{
if(decCheckDecimal != 0)
return decCheckDecimal;
else
return DBNull.Value;
}

The return type is Object which is the base type for everything. This object will either be a boxed value type of System.Decimal or reference type System.DBNull. You can use the .GetType() method to determine which.

Rob Philpott.

Brendan Vogt25-Oct-05 1:06

25-Oct-05 1:06

Thanks.

If the return type is Object, and I do return the decimal value, as for example 10.5, would I still need to convert the value to a decimal where it is being called, or will it assume that it is of type decimal?

Lets say the called is used like this:

paramPound.Value = Globals.CheckDecimalForDB(objProperty.Pound);

Does .value contain a decimal, or must I still use Convert.ToDecimal();??

Do you have any comments on formatting dates and decimal numbers in the datagrid.

Rob Philpott25-Oct-05 1:33

25-Oct-05 1:33

Hi again,

ma se wrote:
...would I still need to convert the value to a decimal where it is being called...

This depends on what you're assigning to. Ultimately the return type is Object even if its a boxed decimal, so unless your assigning to another Object you'd need to cast it. For instance if your paramPound.Value is of type decimal you would have to do this:

paramPound.Value = (decimal)Globals.CheckDecimalForDb(objProperty.Pound)

but this line would throw an invalid cast exception in the instance where you return DBNull.

If paramPound.Value is of type Object, you can leave the cast out, and no exceptions are thrown, but this presumes that paramPound.Value can deal with an object which could either be a boxed decimal or DBNull.

I hope that sort of answers your question...

BTW - I think you are correct to use decimal for currency.

As for the datagrid, I'm afraid I'm unfamiliar with this and have no suggestions.

Rob Philpott.

Brendan Vogt25-Oct-05 1:50

25-Oct-05 1:50

Hi again yes,

This how I create my parameter:

SqlParameter paramPound = new SqlParameter("@Pound", SqlDbType.Money, 8);
paramPound.Value = Globals.CheckDecimalForDB(objProperty.Pound);
objCmd.Parameters.Add(paramPound);

I just have 2 questions:

Firstly, because the SQL Server table field is of type money, can I use a decimal? And secondly, with regards to your cast to decimal, it will throw an exception. So the best way to do this is to leave the cast out?

For if you must know, this is my check function:

public static Object CheckDecimalForDB(decimal decCheckDecimal)
{
if(decCheckDecimal != 0)
return decCheckDecimal;
else
return DBNull.Value;
}

How would you do it? Would you just do a test for this when you create your parameters?

Cheers.

Rob Philpott25-Oct-05 2:05

25-Oct-05 2:05

OK. I think you're code is fine as it is.

SqlParameter.Value is of type Object which expects either a DBNull or a value (which is what you give it), and the type SqlDbType.Money is decimal. No casting is necessary.

One point though - this implementation means that a value of 0.00 can't be put into the database. DBNull is used to mean 'not applicable here' not zero. So for instance if you wanted to maintain the balance of a bank account without any funds in it you couldn't. The balance would not be 0.00, the balance would not exist.

Rob Philpott.

Gavin Jeffrey25-Oct-05 0:00

Gavin Jeffrey

25-Oct-05 0:00

- decimal decEuro = Convert.ToDecimal(txtEuro.Text.Trim()); - would throw an FormatException
- I would say that double would be better for currency
- returned is always object i.e. it is an Object of decimal
- You could look at something like:
System.Globalization.CultureInfo c = new System.Globalization.CultureInfo("en-ZA");//I think?
i don't really know much about this so I can't really help. Or you could format your data in your query before it gets returned to the front end e.g. select convert(varchar(10),DateCaptured,101)... would return me my date already in the format i want
- you could use response.redirect("pageb.aspx?txtFName=" + txtFName.Text + ");
and then at page b you could use Request["txtFName"].ToString();

Brendan Vogt25-Oct-05 1:12

25-Oct-05 1:12

Thanks.

I'm still not 100% sure how to format this in the datagrid to the value I want.

Brian Leach25-Oct-05 10:39

Brian Leach

25-Oct-05 10:39

ma se wrote:
If I have the following, what is the value of decEuro if the textbox txtEuro is empty? decimal decEuro = Convert.ToDecimal(txtEuro.Text.Trim());

The Visual Studio help file tells you (use MSDN if you don't have Visual Studio) that you will throw an ArgumentException if the value is null, FormatException if "value does not consist of an optional sign followed by a sequence of digits (zero through nine) and an optional decimal point symbol.'

ma se wrote:
Is decimal the best data type used for a currency value?

I don't work with currencies, I can't help you there.

ma se wrote:
public static Object CheckDecimalForDB(decimal decCheckDecimal)
{
if(decCheckDecimal != 0)
return decCheckDecimal;
else
return DBNull.Value;
}

The datatype/type returned when decCheckDecimal contains a value, is decimal, or Object?

When it contains a value, it will be a decimal. You will need to caste it as such. The proper technique is:

decimal value = (decimal)CheckDecimalFOrDB( d ) as decimal;
if ( value != null ) {
   ....
}

Again the help file has this documented. Look up 'as operator'.

Can't help you with the Euro Formatting

My suspicion is that you should use the Response.Redirect. The Server.Transfer is performed strictly on the server side, the browser is unaware that it has been directed to a new page. If the user does a refresh, they will be redirected back to the original page.

Response.Redirect causes the browser to request the new page. Values will need to be passed by other means such as a cookie or session state. If session state is used and memory is an issue, be sure to recover the session memory by setting the values to null after you have extracted them.

See the Visual studio help file at ms-help://MS.VSCC.2003/MS.MSDNQTR.2003FEB.1033/dv_vbcode/html/vbtskCodeExamplePassingDataFromOneWebPageToAnother.htm

Brian Leach

Please help me...

KORCARI24-Oct-05 21:39

KORCARI

24-Oct-05 21:39

Hi guys.I need to build a PlotControl where my graph will be shown but I got no idea how to do it.Maybe anybody an help me with any reference?I would be very grateful

Re: Please help me...

Peto198325-Oct-05 2:11

Peto1983

25-Oct-05 2:11

If you tell me more about your plotboard, do you want to draw it with GUI+, maybe make graphics class, I dont know, send me a mail, I try to help you.

Percy Bloomfield
Santa Cruz - Bolivia

C# Reflection

koyllis24-Oct-05 21:06

koyllis

24-Oct-05 21:06

Is There any way to get the method name inside a method.

ie public int GetName { puts("I'm called from function: GetName" }

Re: C# Reflection

Rob Philpott25-Oct-05 0:05