updating using a dataset. - C# Discussion Boards

Justin Garrick27-Oct-04 10:09

27-Oct-04 10:09

Hi,

If I make an HttpWebRequest, i.e. HttpWebRequest request =
(HttpWebRequest)WebRequest.Create("http://www.google.com");, is there any way I can get the IP of the Uri (in this case google). I've fooled around with the .Address property, and looked around in the MSDN library, but I can't seem to find it. Does anyone know what property I should be using?

Thanks,
Justin

Re: Get the IP from HttpWebRequest

Justin Garrick27-Oct-04 15:43

Justin Garrick

27-Oct-04 15:43

Ok, I couldn't figure out how to get the IP address from a HttpWebResponse object, so instead I'm using
IPHostEntry hostentry = Dns.Resolve(uri);
IPAddress = hostentry.AddressList[0];
The problem with the above is that it will not resolve a DNS entry for something like "http://www.google.com", but it will resolve an entry for "google.com" or "www.google.com". However, if you try to create a HttpWebRequest object with either of the latter two uri's, they are invalid - only the first one is valid. I only have one "address bar" in my program, so this is a bit of a problem. So, I need to find a way to get the IP, and create a HttpWebRequest given only one uri - any ideas/suggestions?

Thanks,
Justin

Re: Get the IP from HttpWebRequest

Nick Parker27-Oct-04 17:12

Nick Parker

27-Oct-04 17:12

A quick work around will be a way to format the input from the user, in your case, the address, into an appropriate Uri format so your class can be created. I have written up a simple formatting method that will allow you to accept different formats as you stated above (i.e., www.google.com and google.com) and create the appropriate Uri class from it. Try the following:

private Uri FormatUri(string url)
{
    Uri uri = null;
    if(!url.ToLower().StartsWith("http://"))
    {
        uri = new Uri("http://" + url);
    }
    else
        uri = new Uri(url);
    return uri;
}

So you can use this as follows:

private void button1_Click(object sender, System.EventArgs e)
{
    Uri uri = FormatUri(this.textBox1.Text);
    MessageBox.Show(uri.AbsoluteUri);
}

HTH

- Nick Parker
My Blog | My Articles

Re: Get the IP from HttpWebRequest

Heath Stewart27-Oct-04 21:07

Heath Stewart

27-Oct-04 21:07

While I find it odd that you don't know what server responded to you when you, in fact, made the request (a la HttpWebRequest), you must have some valid reason.

This is possible. Pass HttpWebResponse.Server to Dns.Resolve or similar (like Dns.GetHostByName) and you can get the IP address. If all you wanted was the name, the Server property would return that for you, as it is clearly documented.

The Dns class would not - and should not - return the protocol scheme "http". DNS - or Domain Name Service - only deals with IP<->hostname mapping. A protocol scheme merely indicates to clients what protocol to use to communicate with the server and, more often than note, the default port (HTTP's default port is 80; SMTP's default port is 25; etc.).

This posting is provided "AS IS" with no warranties, and confers no rights.

Software Design Engineer
Developer Division Sustained Engineering
Microsoft

[My Articles] [My Blog]

C# on Linux...?!?

QzRz27-Oct-04 7:24

QzRz

27-Oct-04 7:24

Hi...

Can anyone tell me if it is possible to run/create a C# application on Linux?

I want to know if it can run on MandrakeLinux...!

Thanks...!

QzRz

Re: C# on Linux...?!?

Alex Korchemniy27-Oct-04 7:39

Alex Korchemniy

27-Oct-04 7:39

Yes. Take a look at Mono[^]

This posting is provided "AS IS" with no warranties, and confers no rights.

Alex Korchemniy

Re: C# on Linux...?!?

QzRz27-Oct-04 7:43

QzRz

27-Oct-04 7:43

Thanks...!

You just saved me for a lot of translation from C# to c++ Big Grin | :-D

Thanks again..!

QzRz

updating using a dataset.

steve_rm27-Oct-04 7:13

steve_rm

27-Oct-04 7:13

Hello,

I am having trouble updating to a database using a dataset. My code is listed below with the error description. I hope you can help me.

cnnTeacher.Open();<br />
	<br />
dsTeacher.Clear(); //Clear the dataset of any data before filling<br />
DataRow drUpdateTeacher;<br />
<br />
daTeacher = new OleDbDataAdapter("SELECT * FROM Teacher",cnnTeacher);<br />
OleDbCommandBuilder cbTeacher = new OleDbCommandBuilder(daTeacher);<br />
daTeacher.FillSchema(dsTeacher, SchemaType.Source, "Teacher");<br />
<br />
drUpdateTeacher = dsTeacher.Tables["Teacher"].Rows.Find(txtTeacherID.Text);//Find the row to update<br />
//When the correct row has been found, update the columns in the table.				<br />
drUpdateTeacher["TeacherID"] = txtTeacherID.Text;//Error<br />
drUpdateTeacher["FirstName"] = txtFirstName.Text;<br />
drUpdateTeacher["LastName"] = txtLastName.Text;<br />
drUpdateTeacher["Email"] = txtEmail.Text;<br />
					<br />
daTeacher.Update(dsTeacher,"Teacher");

Error description - SystemNullReferenceException: Object reference not set to a instance of an object

Many thanks in advance,

Steve

Re: updating using a dataset.

Hugo Migneron27-Oct-04 7:49

Hugo Migneron

27-Oct-04 7:49

Hello,
I think it is because you don't initialize your drUpdateTeacher object.
Try to do :
daTeacher.FillSchema(dsTeacher, SchemaType.Source, "Teacher");
//Code to add
drUpdateTeacher = dsTeacher.Tables["Teacher"].NewRow();

drUpdateTeacher = dsTeacher.Tables["Teacher"].Rows.Find(txtTeacherID.Text);//Find the row to update

This would be my first guess.
Anyways, most of the time, this error message indicates that you did not initialize an object before you used it.

Hope this helps

Re: updating using a dataset.

steve_rm27-Oct-04 14:12

steve_rm

27-Oct-04 14:12

Hello,

Thanks for yourr reply.

But won't the NewRow() add a new record to the table. I was trying to update an existing row not add a new one to the table.

Many thanks in advance,

Steve

Re: updating using a dataset.

Hugo Migneron28-Oct-04 3:16

Hugo Migneron

28-Oct-04 3:16

Hello,
No, the NewRow() function does not add a line to the existing table, it creates a line from the row without adding it to the table (it creates the column as they are in the table)
The function DataTable.ImportRow(DataRow row) is the one that adds the line.
You have to create the row with the NewRow function because otherwise, the compiler won't be able to know how many columns there is in the table, what are the columns name/index, etc.
When you create your DataRow object, it has a null value until you write the
row = DataTable.NewRow() statement.

Hope this helps!

Hugo Migneron

Splash Screen

mathon27-Oct-04 6:53

mathon

27-Oct-04 6:53

Hello,

I want to add a Splash Screen to my Smart Device Application. The situation is as follows:

The Form1.cs is my Login Page, the Splash.cs is my Form which should displayed about 3 seconds and then should automatically go on to the MainMenu Form.
To reach that I made the following:

In the Form1.cs exists a button which forwards to the MainMenu with these two lines:

MainMenu mainMenu = new MainMenu();
mainMenu.Show();

In the Constructor of the MainMenu Form I wrote after the InitializeComponent() the following lines:

Splash splash = new Splash();
splash.Show();

And in the Splash.cs I import the following method:

[DllImport("coredll.dll", CharSet=CharSet.Unicode)]
public static extern void Sleep (int dwMilliseconds);

public const int IDC_WAIT = 32514;
public const int IDC_ARROW = 32512;
public const int IDC_IBEAM = 32513;
public const int IDC_CROSS = 32515;
public const int IDC_UPARROW = 32516;
public const int IDC_NO = 32648;
public const int IDC_HELP = 32651;
private System.Windows.Forms.Label label1;
public const int IDC_HAND = 32649;

and in the Splash_Load method I wrote the following:

Sleep(3000);
this.Close();

Unfortunately this does not work correctly. Does anybody know what went wrong?? Frown | :(

Best Regards

mat

Re: Splash Screen

Colin Angus Mackay27-Oct-04 7:20

Colin Angus Mackay

27-Oct-04 7:20

Instead of pInvoking Sleep, why not use the Sleep method build into .NET

See MSDN's library reference for Thread.Sleep[^] for details

Do you want to know more?

Vogon Building and Loan advise that your planet is at risk if you do not keep up repayments on any mortgage secured upon it. Please remember that the force of gravity can go up as well as down.

Re: Splash Screen

Dave Kreskowiak27-Oct-04 11:30

Dave Kreskowiak

27-Oct-04 11:30

On top of what Colin said, the Sleep should not go into the Splash screen. Instead, the code should go into your Main form, using something like:

splash.Show();
Sleep(3000);
splash.Close()

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

Manipulating cmd.exe on another pc

uwgrimlock27-Oct-04 6:48

uwgrimlock

27-Oct-04 6:48

Hi,

I've currently got a program that emulates the command prompt in C#. So my application hooks into cmd.exe and then via a pair of text boxes in my application, I can stream the command prompt input and output back and forth. This works fine on my local machine.

I'm looking to set this up so that there will be 2 applications. On machine A, the application will connect to cmd.exe on machine B. Then from the application on machine A, I can send console commands to machine B's cmd.exe and receive output back.

Does anyone have any recommendations as to how I should go about this?
Any help is much appreciated

Re: Manipulating cmd.exe on another pc

Nick Parker27-Oct-04 8:07

Nick Parker

27-Oct-04 8:07

I would suggest that you look into .NET remoting. MSDN has documented this and the following link should get you started: .NET Remoting Overview - .NET Framework Developer's Guide[^]

- Nick Parker
My Blog | My Articles

TAPI

Mridang Agarwalla27-Oct-04 5:26

Mridang Agarwalla

27-Oct-04 5:26

could anyone helpme out....i want to make a windows application that has phone, fax, answering machine facilites...this can be acheived through TAPI provided u have a TAPI compliant modem....how do i get strated on this...all the hlp on MSDN is in C/C++ and i cant make head or tails of it....and....i misgt be a little slow in replying as i am unable to access the internet everyday...

Re: TAPI

Nick Parker27-Oct-04 8:03

Nick Parker

27-Oct-04 8:03

I have discussed this many times before in the C# forum, please review my previous post[^] regarding this topic.

- Nick Parker
My Blog | My Articles

Re: TAPI

Michael P Butler27-Oct-04 23:25

Michael P Butler

27-Oct-04 23:25

Do yourself a big favour. TAPI and C# are a bad combination, especially if you've never written any TAPI applications in C++ before.

My strategy when writing TAPI applications in C# was to use COM Interop with my own TAPI COM wrapper. I also built an XML service in C++ that fired the TAPI events via TCP as XML.

Until Microsoft come out with a better approach to managed TAPI, you are better off writing your TAPI code in C++.

Michael

CP Blog [^]

C# p/invoke the sendmessage(Hwnd,....)

ting66827-Oct-04 5:16

ting668

27-Oct-04 5:16

Hi~

The wparam and lparam is the pointer of the variable. I would like to pass string to the other window using sendMessage method in C# by P/Invoke. Then, as wparam and lparam is pointer and C# no support pointer. Then how to send the message with string in C# using sendMessage?

Re: C# p/invoke the sendmessage(Hwnd,....)

Colin Angus Mackay27-Oct-04 5:33

Colin Angus Mackay

27-Oct-04 5:33

http://pinvoke.net/[^]

I'd give you a reference directly to the page you need, as there is an example of what you want, but the site doesn't allow you to directly go to a page. You have to search or browse for the API you are looking for.

Do you want to know more?

Vogon Building and Loan advise that your planet is at risk if you do not keep up repayments on any mortgage secured upon it. Please remember that the force of gravity can go up as well as down.

Re: C# p/invoke the sendmessage(Hwnd,....)

Nick Parker27-Oct-04 8:00

Nick Parker

27-Oct-04 8:00

Colin Angus Mackay wrote:
I'd give you a reference directly to the page you need, as there is an example of what you want, but the site doesn't allow you to directly go to a page. You have to search or browse for the API you are looking for.

Not entirely true, here is the link: SendMessage[^]. Wink | ;)

- Nick Parker
My Blog | My Articles

C# showing forms problem

ting66827-Oct-04 5:11

ting668

27-Oct-04 5:11

For the pocket pc,
why, sometime when the program try to show a form by calling the .Show() method, the form was not shown. However, the form title appear in the task list(memory)?

System.Web.Mail

Hugo Migneron27-Oct-04 4:50

Hugo Migneron

27-Oct-04 4:50

Hi,
I am using the System.Web.Mail in a C# program to send email and i want to make sure my program will be usable. I would like to know if everyone who has dotnet installed (dotnetfx.exe for example) will be able to use the program.
I think there is an issue with the CDO/CDONT but i am not quite sure what it is. My application must support WinME, Win2000 and WinXP with dotnet installed. If anyone knows more about the System.Web.Mail compatibility, it would be really appreciated Smile | :)

Thanks

HM

Re: System.Web.Mail

Salil Khedkar27-Oct-04 21:10

Salil Khedkar

27-Oct-04 21:10

The documentation for System.Web.Mail.SmtpMail states that only the following platforms are supported: Windows 2000, Windows XP Professional, Windows Server 2003 family.

Indicative code for getting the OS and CLR version numbers is as folows:

using System;<br />
Console.WriteLine("OSVersion: {0}", Environment.OSVersion.ToString());<br />
Console.WriteLine("CLRVersion: {0}", Environment.Version.ToString());

Please see my article
here[^] for more details:

Salil Khedkar [^]

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.