C# Discussion Boards - CodeProject

15-Aug-06 23:45

Hi,

Here's some code that fully explains how I am obviously missing something that everyone else seems to understand but me:

    private decimal getBalanceOH(DateTime fDate)<br />
    {<br />
      MessageBox.Show("fDate passed to getBalanceOH is " + fDate);<br />
      decimal BalanceOH = 0;<br />
      string reportDate = fDate.ToString("MM/dd/yyyy");<br />
      DataTable table = myclubDataSet.Tables["TresReports"];<br />
      string expression;<br />
      expression = "ReportDate = #" + reportDate + "#";<br />
      DataRow[] rows = table.Select(expression);<br />
      if (rows.Length == 0)<br />
      {<br />
        MessageBox.Show("Could not find the information sought");<br />
      }<br />
      else<br />
      {<br />
        for (int i = 0; i < rows.Length; i++)<br />
        {<br />
          <br />
          <br />
          BalanceOH = Convert.ToDecimal(myclubDataSet.Tables["TresReports"].Rows[i]["BalanceOH"]);<br />
          MessageBox.Show("BalanceOH to sent to results :" + BalanceOH);<br />
          DateTime repDate = Convert.ToDateTime(myclubDataSet.Tables["TresReports"].Rows[i]["ReportDate"]);<br />
<br />
          if (repDate != fDate)<br />
          {<br />
            MessageBox.Show("I dunno what I'm doing");<br />
          }     <br />
                    <br />
          return BalanceOH;<br />
        }<br />
      }<br />
      MessageBox.Show("Error");<br />
      return BalanceOH;<br />
    }

It comes up "I dunno what I'm doing" all the time.

I have read that many articles and messages that it has become clear to me that I MUST be missing something.

I would greatly appreciate anyones input.

Thank you. Cry | :((

-- modified at 5:50 Wednesday 16th August, 2006

Glen Harvy

Very, very frustrated at the moment

albCode16-Aug-06 0:14

albCode

16-Aug-06 0:14

Glen Harvy wrote:
BalanceOH = Convert.ToDecimal(myclubDataSet.Tables["TresReports"].Rows[i]["BalanceOH"]);

BalanceOH = decimal.Parse(myclubDataSet.Tables["TresReports"].Rows[i]["BalanceOH"].ToString());

Glen Harvy wrote:
DateTime repDate = Convert.ToDateTime(myclubDataSet.Tables["TresReports"].Rows[i]["ReportDate"]);

System.IFormatProvider FormaT = new System.Globalization.CultureInfo("sq-AL", true);<br />
DateTime repDate = DateTime.ParseExact(myclubDataSet.Tables["TresReports"].Rows[i]["ReportDate"].ToString(), "yyyy-MM-dd", FormaT );

Glen Harvy16-Aug-06 2:14

16-Aug-06 2:14

I can pass any date I like - if it is a valid ReportDate then the program runs without error BUT always returns the value of Row 0 no matter what. The problem is that I can't figure out how to get the proper row to return.

Glen Harvy

CooperWu16-Aug-06 0:20

16-Aug-06 0:20

I think the problem is here

<br />
 DateTime repDate = Convert.ToDateTime(myclubDataSet.Tables["TresReports"].Rows[i]["ReportDate"]);<br />
<br />
if (repDate != fDate)<br />
{<br />
MessageBox.Show("I dunno what I'm doing");<br />
} <br />

the fDate may contains hh:mm:ss value, but the repDate is 00:00:00.
e.g

<br />
 fDate = DateTime.Now; //fDate=2006/08/16 18:14:05<br />
 repDate = Convert.ToDateTime("2006/08/16"); // repDate would be: 2006/08/16 00:00:00<br />

and 2006/08/16 18:14:05 != 2006/08/16 00:00:00

so you will always get "I dunno what I'm doing" all the time.

Glen Harvy16-Aug-06 2:17

16-Aug-06 2:17

WuJunyin wrote:
so you will always get "I dunno what I'm doing" all the time.

There's a problem with the programming logic not the date formats.

I am NOT getting the Row I am looking for returned and I don't know how to do that?

Glen Harvy

V.16-Aug-06 2:25

16-Aug-06 2:25

I'm guessing that maybe the values are the same, but the objects are not.
I'm not sure how the == operator compares the DateTimes, but it could be that the culture eg. (or something else) is different. Maybe you can print out the values of several properties and compare them.

godd luck.

I've found a living worth working for, but I haven't found work worth living for.

<marquee> Beer | [beer]

Guffa16-Aug-06 2:50

Guffa

16-Aug-06 2:50

As DateTime is a value type, the == operator will be comparing the values, not the objects.

The actual values that will be compared is the value of the Ticks property. A tick is 100 nanoseconds, so the values have to be exactly the same to be equal. If they are off by 0.0000001 seconds, they are not equal.

---
b { font-weight: normal; }

V.16-Aug-06 3:12

16-Aug-06 3:12

Guffa wrote:
As DateTime is a value type, the == operator will be comparing the values, not the objects

you're probably right

Guffa wrote:
The actual values that will be compared is the value of the Ticks property. A tick is 100 nanoseconds, so the values have to be exactly the same to be equal. If they are off by 0.0000001 seconds, they are not equal

this, I knew

tnx

I've found a living worth working for, but I haven't found work worth living for.

<marquee> Beer | [beer]

Glen Harvy16-Aug-06 12:56

16-Aug-06 12:56

A. The ReportDate is passed to the select statement.
B. The select statement supposedly retrieves all rows equalling that value.
C. The select statement returns the value contained in the ReportDate AND the BalanceOH fields.
D. Irrespective of what date I pass to the select statement, it always retieves row 0, etc AND the comparative statement is only there for cosmetic and confirmation of B. not returning the correct BalanceOH figure.
E. The value of BalanceOH is not the balance corresponding to the date I want.
F. The comparison is only made to confirm to me that I don't know what I'm doing.

If there was a problem with the formatting of the dates, then I don't see why the select statement is retrieving any rows at all.

What I think is wrong is that I am always going to get the value 0 returned becuase that is what the value of i is. Shouldn't I be passing the value of the row number corresponding to the selected ReportDate of the datatable?

BalanceOH = Convert.ToDecimal(myclubDataSet.Tables["TresReports"].Rows[i]["BalanceOH"]);

Glen Harvy

doubt on URLDownloadToFile

V.16-Aug-06 20:32

16-Aug-06 20:32

Glen Harvy wrote:
If there was a problem with the formatting of the dates, then I don't see why the select statement is retrieving any rows at all.

Actually I'm not talking about the formatting.
What I thought was that the culture retrieved from the database was eg. EN-us while the culture you are working with was Neutral. Furthermore, according to Guffa, the "==" operator should only check the values. In that case I was wrong.

How many rows do you retrieve? Isn't there a possibility to step into the code?
Also, as mentioned above by Guffa, one thick difference is a difference.
You could check eg. on year, month, and day instead of the entire DateTime object.
The problem probably lies in a very small corner.

Glen Harvy wrote:
What I think is wrong is that I am always going to get the value 0 returned becuase that is what the value of i is. Shouldn't I be passing the value of the row number corresponding to the selected ReportDate of the datatable?

BalanceOH = Convert.ToDecimal(myclubDataSet.Tables["TresReports"].Rows[i]["BalanceOH"]);

I'm not sure what you mean by this, but a DataSet is just like a the view you get when executing a select statement. What you can do is execute the select statement in the database itself. That view should exactly be the contents of your DataSet. If you iterate through it with a for loop you should get each row of that view.

Good luck.

I've found a living worth working for, but I haven't found work worth living for.

<marquee> Beer | [beer]

Bibhu shankar15-Aug-06 23:19

Bibhu shankar

15-Aug-06 23:19

If any body call URLDownloadToFile using c#.net in web application,
what are the parameters that i shall pass.

Bibhu

display data on textboxes from database using classes [modified]

Mamphekgo15-Aug-06 22:01

Mamphekgo

15-Aug-06 22:01

Hi. i am still new on C#.i am trying to display data on the texboxes from database using classes but it doesn't display any data where as is there here is my class.

public void SeachCustomer(string CName,string CNum)
{
CustomerName = CName;
Barcode1 = CNum;

SqlConnection conn = new SqlConnection();
conn.ConnectionString = "integrated security=SSPI;initial catalog=Phusa;server = za211149;persist security info=False";
conn.Open();
try
{
SqlCommand cmdSearch = new SqlCommand();
cmdSearch.Connection = conn;
cmdSearch.CommandText = "SELECT CustomerName FROM Events WHERE Barcode1 =@Barcode1";

SqlParameter Bar = new SqlParameter();
Bar.ParameterName = "@Barcode1";
Bar.Direction = System.Data.ParameterDirection.Output;
Bar.Value = Barcode1;
cmdSearch.Parameters.Add(Bar);
SqlParameter Nam = new SqlParameter();
Nam.ParameterName="@CustomerName";
Nam.Direction = System.Data.ParameterDirection.Output;
Nam.Value =CustomerName;
cmdSearch.Parameters.Add(Nam);

SqlDataReader dr =cmdSearch.ExecuteReader();

while(dr.Read()==true)
{

CustomerName = dr["CustomerName"].ToString();

}
}
catch(Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
conn.Close();
}

-- modified at 4:02 Wednesday 16th August, 2006

Re: display data on textboxes from database using classes

coolestCoder16-Aug-06 0:18

coolestCoder

16-Aug-06 0:18

Hi,
First of all you haven't added the 'Bar' parameter.

Mamphekgo wrote:
cmdSearch.Parameters.Add(Nam);

As shown above only the 'Nam' param is added.

Mamphekgo wrote:
i am trying to display data on the texboxes from database

You have not written any code to display the data ?

Another problem is that CustomerName will only contain the last row's data , bcoz u r not concatenating the strings..

Mamphekgo wrote:
CustomerName = dr["CustomerName"].ToString();

Try to provide complete code if you have missed something or try to correct the above said errors and check for the desired result.

"A good programmer is someone who looks both ways before crossing a one-way street." -- Doug Linder

Anant Y. Kulkarni

Re: display data on textboxes from database using classes

Mamphekgo16-Aug-06 0:54

Mamphekgo

16-Aug-06 0:54

actually my code can see that there is data on the database because when i use messagebox to search if ever there is something ot the database it shows that it found the record.but data cannot display on the texboxes,here i am trying to call my class to display data.

SearchCustomers search = new SearchCustomers();
string Barcode1;
string CustomerName ="";
string Barcode;
string ProductName="";
string Price = "";
if(txtBarcode.Text.Length <4)
{
Barcode1 =txtBarcode.Text;
CustomerName = lblCustomerName.Text;
search.SeachCustomer(CustomerName,Barcode1);
}
else
{
Barcode = txtBarcode.Text;
lblProductName.Text = ProductName;
lblPrice.Text =Price.ToString();
search.SeachProduct(Barcode,ProductName,Price);
}

Re: display data on textboxes from database using classes

coolestCoder16-Aug-06 1:13

coolestCoder

16-Aug-06 1:13

Hi,
Sorry, I didnt got you still. Since you are using the SearchCustomer function to search the db, but it dosent returns any value ?

Mamphekgo wrote:
search.SeachCustomer(CustomerName,Barcode1);

Mamphekgo wrote:
when i use messagebox to search

I didnt understand where you are applying this message box ? Inside SearchCustomer or where you are using the object. Sorry but i can see only one problem that ur SearchCustomer function should return the Customer name which you will then set in any text box or other controls.

Hope i am guessing it right ! Smile | :)

"A good programmer is someone who looks both ways before crossing a one-way street." -- Doug Linder

Anant Y. Kulkarni

which method is the best than others and why? (Type convert)

CooperWu15-Aug-06 21:59

Re: which method is the best than others and why? (Type convert)

15-Aug-06 21:59

the sample code is here: (in .NET Framework 2.0)

<br />
            object obj = "abc";<br />
            string s2 = obj as string;  // method 1<br />
            string s3 = (string)obj;    // method 2<br />
            string s4 = obj.ToString(); // method 3<br />

thanks in advance Smile | :)

Guffa15-Aug-06 22:28

Guffa

15-Aug-06 22:28

If you know that the object contains a string:

string s3 = (string)obj; // method 2

If the object may contain other types of data:

string s2 = obj as string; // method 1

The s2 variable will be null if the object did not contain a string.

If you want a string value whatever the object contains:

string s4 = obj.ToString(); // method 3

The s4 variable will contain the string representation of whatever the object contains. If the object for an example contain an integer with the value 42, you will get the string value "42".

---
b { font-weight: normal; }

Re: which method is the best than others and why? (Type convert)

CooperWu15-Aug-06 22:40

Re: which method is the best than others and why? (Type convert)

15-Aug-06 22:40

I always use this method to get the string, because I can sure its type is string.

<br />
string s3 = (string)obj; // method 2<br />

if the obj is not a string, then it would occur a exception.

leppie15-Aug-06 22:45

leppie

15-Aug-06 22:45

An implicit cast is safer that using 'as', but I am lazy, so I prefer to use 'as' Smile | :)

xacc.ide-0.2.0.57 - now with C# 2.0 parser and seamless VS2005 solution support!

Re: which method is the best than others and why? (Type convert)

CooperWu15-Aug-06 22:56

Re: which method is the best than others and why? (Type convert)

15-Aug-06 22:56

<br />
            object a = 123;<br />
<br />
            try {<br />
                string s1 = (string)a;<br />
                Console.WriteLine("method 1 value: {0}", s1);<br />
            }<br />
            catch {<br />
                Console.WriteLine("method 1 error.");<br />
            }<br />
<br />
            try {<br />
                string s1 = a as string;<br />
                Console.WriteLine("method 2 value: {0}", s1);<br />
            }<br />
            catch {<br />
                Console.WriteLine("method 2 error.");<br />
            }<br />
<br />
            // result:<br />
            method 1 error. <br />
            method 2 value: //here is a null value.<br />

use 'as' can replace try-catch block. haha...

Guffa15-Aug-06 23:20

Guffa

15-Aug-06 23:20

leppie wrote:
An implicit cast is safer that using 'as', but I am lazy, so I prefer to use 'as'

Implicit cast? Don't you mean an explicit cast?

If you use a cast, you will get the exception at the instruction trying to do the cast. If you use "as", you will get a null reference exception somewhere else in the code, when you try to use the reference from the failed cast. Or even worse, it will silently store the value somewhere, and you get the error message weeks later when someone tries to use the stored value...

I always try to write code so that the exception occurs where the error is, then it's a lot easier to locate the source of the error. Smile | :)

---
b { font-weight: normal; }

Re: which method is the best than others and why? (Type convert)

leppie15-Aug-06 23:40

leppie

15-Aug-06 23:40

Guffa wrote:
Implicit cast? Don't you mean an explicit cast?

Hehe, yes

xacc.ide-0.2.0.57 - now with C# 2.0 parser and seamless VS2005 solution support!

Re: which method is the best than others and why? (Type convert)

beatles169215-Aug-06 23:07

beatles1692

15-Aug-06 23:07

First:
I'm a fan of strong typed programming (that i think it will prevent many kind of bugs Smile | :)

)
So I recommand using string obj="abc";
Second:
But there are times that you should use weak types
then I prefer obj.ToString();
because that one day may be I want to pass another type of object to my method
for example:
object obj=new User();
then my code will not crash but there is one thing that I shoule be aware of :NULL Reference !!! (if obj is null my colde will crash either way)
Then we can a NullSafe static method somewhere in our code

<br />
public static string GetNullSafeString(object obj)<br />
{<br />
return (obj==null?null:obj.ToString());<br />
}<br />

This way I will take advantages of polymorphism (object.ToString() ) and be sure that nothing can harm my code.

Regards

Re: which method is the best than others and why? (Type convert) [modified]

CooperWu16-Aug-06 0:00