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Problem in creating objects of derived class

tttyip12-Jul-05 20:28

12-Jul-05 20:28

Hi all, I am new in C#.
I have two classes, class A and class B. Class B is inherited from class A.
When I create an object of class B, will an object of class A also be created?

In addition, if class A has a member "public string myName", after I create an object of class B, the created instance also can access myName, but what does the statement " base.myName = "HELLO" " mean? I know it assign "myName" of the base class (class A) with "HELLO", but why do we assign member of the base class if no instance of the base class created?

Regards,
Tommy

Re: Problem in creating objects of derived class

S. Senthil Kumar12-Jul-05 21:15

S. Senthil Kumar

12-Jul-05 21:15

When you create an instance of a derived class, an instance of the base class (usually embedded in the instance of the derived class) is automatically created for you. That answers your second question as well, there is an instance of the base class.

You can usually get away without using the base prefix, as public and protected members of the base class are accessible from the derived class directly. Usually, the base prefix is used to call the base class implementation from within overridden functions and to disambiguate functions and member variables.

Regards
Senthil
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Re: Problem in creating objects of derived class

tttyip13-Jul-05 16:11

tttyip

13-Jul-05 16:11

Thanks for your answer~~~
I have some more questions.
1) When a member in the base class (class A) is declared as private (say "private int x"), will the instance of the derived class (class B) has a that private member? Is that an inherited class always inherits all members of the base class but cannot access the private members? (For example, in this case, class B also has "private int x", but cannot access "x" )?

2) When a method in the base class (class A) is overridden by the derived class (class B), is that the overridden version of the method be always called?
For example,
class A
{
public virtual void Test()
{
Console.WriteLine("This is A");
}
}

class B : A
{
public virtual void Test()
{
Console.WriteLine("This is B");
}
}

static void Main()
{
B b = new B(); A a = b;
b.Test();
a.Test();
}

The above code sample is copied from a book, but I am confused.....
I know the statement "b.Test()" will cause the output "This is B"
but how about "a.Test()", as a is referenced to the object of type B, which version of the method will be called?
What is meant by "A a = b"?

Again, thanks a lot for your help!!

Regards,
Tommy

IIS Root Path location

Sau Fan Lee12-Jul-05 17:28

Sau Fan Lee

12-Jul-05 17:28

Hi, I'm trying to find out where the root path (ie. the physical folder of "http://mydomain.com/") is programmatically, but I'm not sure how to do this. After researching a bit, I came up with the following information:-

In Wise Installer and Install Shield they check for the registry value under HKLM\Software\Microsoft\InetStp\PathWWWRoot, but this only points to the default folder at installation, not the current (possibly moved) folder location.
In Windows XP, I'm able to find the correct location under HKLM\System\CurrentControlSet\Services\W3SVC\Parameters\Virtual Roots, but this key does not exist in Windows 2003 Server operating system. In fact, on Windows 2003, I can't find the correct location anywhere in Registry! Is there a way to locate the right folder independent of any machine?
I know that in .NET it is possible to use System.DirectoryServices.DirectoryEntry("IIS://mydomain.com/W3SVC") to locate the correct path, but I'm trying to find an easier way to do this - by using only files and registry. Using DirectoryEntry to query the IIS service may also result in a permission denied problem.

What I'm trying to do is to build a setup package in Install Shield to deploy a web-application. Since Install Shield can't locate the IIS root path correctly, I have to manually set the path myself. The capability of the Install-Script that comes with Install-Shield is limited, therefore I cannot use the third option above.

So can anyone shed a light here? Thanks in advance!

> whoami
The system is unable to identify you when you don't even know your name!

Re: IIS Root Path location

Expert Coming12-Jul-05 18:02

Expert Coming

12-Jul-05 18:02

I would have the person manually set the path for your app, as they may have their server set up where the server has the files on a remote computer.

Ms Word Field Codes

bootn12-Jul-05 17:05

bootn

12-Jul-05 17:05

I am lookinf for a way to insert data into Field codes in Ms Word from C#, I have been able to get it to open up the template and insert the data but i cant find anyway to insert it at the point where the codes are (it just places the text at the top)

Anybody know of a way to reference the Fields?

Cheers

Re: Ms Word Field Codes

ekynox13-Jul-05 19:29

ekynox

13-Jul-05 19:29

how about invoking the find & replace method.

Save as "TXT" File

tatchung12-Jul-05 15:47

tatchung

12-Jul-05 15:47

Hi! Im trying to create a form with a button that saves the output as a "text" file. My problem is that this code compiles without any exceptions however it tends to hang at runtime. Can someone please tell me what is wrong with my code and if i'm missing anything. The output is bound to a grid and shows a couple of data based on my drop down list.

private void btnSave_Click(object sender, System.EventArgs e)
{
OdbcConnection cnn = new OdbcConnection();

cnn.Open();

OdbcCommand cmmd = new OdbcCommand();
OdbcDataAdapter adp = new OdbcDataAdapter (cmmd);
DataTable dt_emp = new DataTable();
adp.Fill(dt_emp);

System.Text.StringBuilder sb = new System.Text.StringBuilder();

for(int i=0;i<=dt_emp.Rows.Count - 1; i++)
{
for(int q=0;q<=dt_emp.Columns.Count - 1; q++)
{
sb.Append(dt_emp.Rows[i][q].ToString());
}
sb.Append("
");
}
Response.Clear();
Response.AddHeader("content-disposition", "attachment;filename=*.txt");
Response.Charset = "";
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.ContentType = "application/vnd.text";
System.IO.StringWriter strWrite = new System.IO.StringWriter();
System.Web.UI.HtmlTextWriter htmlWrite = new System.Web.UI.HtmlTextWriter(strWrite);
Response.Write(sb.ToString());
}

Big Grin | :-D

dt_emp is the data passed. Thanx in advance for all your replies!!!