Re: Accessing Forms - C# Discussion Boards

13-Jul-04 6:11

If you want, you can define a non-default constructor that sets fields to the parameters you specify, and initializes the other fields to whatever you want. You cannot define a default constructor (i.e., a constructor with no params) for a struct, though.

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Accessing Forms

Mehbub13-Jul-04 5:02

Mehbub

13-Jul-04 5:02

Hi,

I am too embarrassed to ask this silly question. But I need help. Can any1 tell me, how can I access between forms in C#? For some weird reason I can’t access. I created an object of the form I am trying to access but it’s referring to null.

Say, i have got two forms name "formA" and "formB". I have got five buttons in "formA". How can i access those buttons from formB.

N.B. All the button got public access.

If anyone could help, it would be greatly appreciated. I could attach sample code but i can't see any options here. So, if u give me e-mail then i could send it to ya.

Ta

B

Tom Larsen13-Jul-04 5:27

Tom Larsen

13-Jul-04 5:27

Well Forms.Controls is public and should be available to anyone outside the "formA" object. I'm kind of confused how you don't have access to either this or the individual controls if you claim they are all public.

Colin Angus Mackay13-Jul-04 6:03

Colin Angus Mackay

13-Jul-04 6:03

To add to what Tom said. You should not declare fields in C# as public, you should declare them as private or protected and then provide public properties to access them. Declaring fields as public breaks the concept of encapsulation in Object Orientation.

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Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!

Dave Kreskowiak13-Jul-04 12:46

Dave Kreskowiak

13-Jul-04 12:46

You might want to check out the MSDN article Working with Multiple Forms in Visual Basic .NET: Upgrading to .NET[^]. I know it's written in VB, but it explains the concepts behind multiple forms and passing data between them.

RageInTheMachine9532
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Weiye Chen13-Jul-04 19:36

Weiye Chen

13-Jul-04 19:36

Mehbub wrote:
I could attach sample code but i can't see any options here

Try pasting the code section where you create the form and it is refering to null.

<font=arial>Weiye Chen
Life is hard, yet we are made of flesh...

Viewing Exported Functions and Parameters in a DLL

Weiye Chen13-Jul-04 20:52

Weiye Chen

13-Jul-04 20:52

Ok, i have received your code. Let me paste some of it here so that the rest of the developers can give their advice too.

FormA.cs
private void Form1_Load(object sender, System.EventArgs e)
{
  Form frmB = new FormB();
  frmB.MdiParent = this;
  frmB.Show();			
}
 
FormB.cs
private void btnAccessFormA_Click(object sender, System.EventArgs e)
{
   //I have created a method called "test". I can't access that method either. And 
   // it got public access.
   Form frmA = new FormA();					
   //This bit of code doesn't work. Cause the object(frmA) i created is referin to null.
// frmA.button1.Visible = true;
// frmA.button2.Visible = true;
// frmA.button3.Visible = true;
// frmA.button4.Visible = true;
// frmA.button5.Visible = true;
// frmA.button6.Visible = true;
}

Mehbub wrote:
How can i access those buttons from formB.

You can't access the same form A's buttons in form B by creating Form A again. Since FormA is your mdi parent and FormB is the child, you can use the MdiParent property of FormB. e.g.

FormB.cs
private void btnAccessFormA_Click(object sender, System.EventArgs e)
{
   // Get your parent form, which is FormA in this case and access your
   // button since you have set it as public.
   this.MdiParent.button1.Visible = true;
}

I'm not sure if you need to cast it to FormA first like :

((FormA)this.MdiParent).button1.Visible = true;

I don't have VS.NET on my pc here to test it out.

<font=arial>Weiye Chen
Life is hard, yet we are made of flesh...

Mr. Rogers13-Jul-04 4:22

Mr. Rogers

13-Jul-04 4:22

Lately I've been getting pretty excited with Interop stuff, but I have one problem, I have no idea what the parameters for a particular .dll method are. I know how to view all the exported functions in a method using DUMPBIN or LINK (if anyone knows a better way, I'm all ears) but it doesn't tell me anything about the parameters. Any ideas?

Re: Viewing Exported Functions and Parameters in a DLL

Heath Stewart13-Jul-04 4:33

Re: Viewing Exported Functions and Parameters in a DLL

13-Jul-04 4:33

If you're talking about native DLLs (which you most likely are since you're viewing the EAT with DUMPBIN), this is not even possible. The exported functions are merely RVAs (relative virtual addresses). The execution stack contains pointers or data that the function call pops from. The parameters are not known except by the function itself, so they are not in the EAT (export address table).

All you can do is consult the documentation. If these are Windows DLLs, most APIs are documented in the MSDN Library[^], which should be your first stop for any questions about Windows platform developer (contains the Platform SDK, the .NET Framework SDK, Web Development, and many other Windows-related documentation).

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Mr. Rogers13-Jul-04 4:51

Mr. Rogers

13-Jul-04 4:51

Heath Stewart wrote:
If you're talking about native DLLs (which you most likely are since you're viewing the EAT with DUMPBIN), this is not even possible.

That's really good to know. Thanks a ton Heath. Looks like you're answering everybody's questions today.

How to get the time from a computer

Stuggo13-Jul-04 4:11

Stuggo

13-Jul-04 4:11

Hi all,

I'd like to know how would i be able to code an application to copy the time (copy a time stamp) from a client computers clock.

Example Program:
A simple windows application with a button on it,
when i click the button,
the client computer returns a time stamp or time strap from the computer's clock to the form "04:17pm", to a label or textbox.

The source code would be very much appreciated ..!

Thanx!

Re: How to get the time from a computer

Heath Stewart13-Jul-04 4:20

Response.Redirect is not working.. a peculiar problem..One solution found !!

13-Jul-04 4:20

Logically, you should look at the DateTime structure in the .NET Framework SDK, which has a static property called Now. If you further look at the documentation for ToString, the solution's quite obvious:

textBox1.Text = DateTime.Now.ToString("hh:mmtt");

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PhaniKatakam13-Jul-04 2:07

PhaniKatakam

13-Jul-04 2:07

I would like to share a solution with all of you guys to the Response.Redirect problem.
I have a scenario:
1. An asp page containing two submit type buttons 'Back' and 'Save'.
2. Save may do some action and stay in the same page..
3. But Back would do same as save button..but Goes to Home Page.
4. U may have Save_Click () serverside code in aspx.cs
5. U can simulate the same from back.. and also hidBack to maintain from which button its coming from...
<input type="image" id="Button2" style="Z-INDEX: 101; LEFT: 304px; POSITION: absolute; TOP: 136px"
value="Back" OnClick="return ClickBack()">
<script language="javascript">
function ClickBack()
{
document.Form1.hidBack.value = "YES";
document.Form1.Button1.click();
//IMPORTANT:: RETURN FALSE TO NULLIFY POSTING BY BACK BUTTON.
return false;

}
6. Server side code may look as
private void Save_Click(object sender, System.EventArgs e)
{

if(Request.Form["hidBack"] == "YES")
{
Page.Response.Redirect("Home.aspx",false);
}
Response.Write(" U pressed first Button");
}
</script>
7.if WE DONT HAVE //IMPORTANT:: code line, it will postback twice to the server..there by Response.Redirect doesnt work.
8. Any other observations?? thanks

Phani, Virtusa.

Re: Response.Redirect is not working.. a peculiar problem..One solution found !!

Heath Stewart13-Jul-04 4:13

Re: Accessing HTML control

13-Jul-04 4:13

This question belongs in the ASP.NET forum.

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Accessing HTML control

Padmavathi13-Jul-04 1:26

Padmavathi

13-Jul-04 1:26

I am creating a web page in C# using XML and XSLT. I am able to access the web controls but I am unable to access the 'file' control.

I am using the code in C# like this

XPathDocument ctrlCategoryDoc = new XPathDocument(Server.MapPath("XML/NewCategory.xml"));
XPathNodeIterator itr = ctrlCategoryDoc.CreateNavigator().Select("//Ctrl");
System.Text.StringBuilder sb;
sb = new System.Text.StringBuilder();
// foreach Ctrl
while (itr.MoveNext())
{
// get the control name
string controlName = itr.Current.GetAttribute("name", "");
sb.Append(controlName);
sb.Append(" : ");
// get the control
object ctrl = FindControl(controlName);
}

the object 'ctrl' contains name of the control in case of web control but in case of html control () it is giving undefined value.

can anyone tell me the solution for this

Heath Stewart13-Jul-04 4:07

Problem when Distributing A C#.Net Application

13-Jul-04 4:07

For one, this belongs in the ASP.NET forum.

Also, drop the spaces in sb.Append(" : ");. You won't find a control within an INamingContainer implementation named like that.

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Axonn Echysttas13-Jul-04 1:23

Axonn Echysttas

13-Jul-04 1:23

Hi everybody Smile | :)

. I got a little question about distributing a .Net C# Application. Many of you already did such things, and maybe you find the time to give me a hint on doing this Smile | :)

I created a small C# Application and I wish to upload it so that anybody can use it. I gave it to a friend for testing but the problem is that the Application crashes when you try to run the executable. The target computer already had the .Net Framework 1.1 installed.

What I sent to my friend is the executable and two DLLs. The program uses the WinSock control and the two DLLs are something like AxInteropWinSock.dll or something like this, the only difference is that one of them does not have the "Ax" in its name. This is not so important... what's important is that I sent the .exe and the two DLLs in the same folder. I took them from the "Release" folder of my .Net Solution, after I ran the solution using "Release" configuration.

I saw on the Internet stuff about using MSI files to make a setup or assemblies. I don't know how to use those and the Microsoft documentation is terrible. I would prefer to give this to somebody in a zip file, without any complicated setups and stuff like that. It's a simple application, I'd rather avoid using MSI files and so on.

Any help is greatly appreciated, thank you for your time and have a nice day.

Axonn.

The Greater Mind Balance

Heath Stewart13-Jul-04 3:56

13-Jul-04 3:56

MSI is not a magic bullet that will solve your problems. Obviously, something is missing. If all you use MSI for is copying those assemblies into a folder, then something as simple as COPY or XCOPY or just zipping it up will do fine.

The difference between Interop.something.dll and AxInterop.something.dll is, by default, that the Interop assembly contains the typelib wrapper (RCW, or Runtime Callable Wrapper) and the AxInterop assembly contains the control(s) that extend AxHost, a Control which wraps ActiveX controls.

Distributing those assemblies isn't enough, however. Since they are only wrappers, you need to distribute the WinSock COM control that you're wrapping. All those assemblies do is make the COM control and typelib useable in .NET (through the RCW).

This is where MSI would be handy. COM controls need to be registered on the system and MSI can do that easily. You can add the file to the File System editor and in the file's properties (in the PropertyGrid), set the registration to SelfReg (something like that).

You don't need to do this, though. If you don't plan on mass-deploying this, just direct users to download the WinSock COM control and install it it, if it has it's own installer.

If you do want to distribute this to anyone, though, I'd recommend using an MSI package. VS.NET's Windows Installer projects are very simple to learn, but are by no means complete (for our installs, I use Wise for Windows Installer, which is a full-blown authoring package for MSIs and MSMs from Wise[^]). The VS.NET is simple to use and you should explore it a little.

For example, in the File System editor you can add folders to whatever pre-defined folder you want, then add your project outputs (handy when you want to maintain version compatibility within a solution). Just right click in the folders and seld Add File, choose Project, browse to the project you want and select Build Ouput. Now when you build the MSI project it will make sure the other projects are up-to-date and automatically grab the build outputs (the assemblies) from the projects' target directories.

Also add the COM control if the VS.NET Windows Installer project doesn't do it already (it often will). Make sure that it's set to register itself as I mentioned above.

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Axonn Echysttas13-Jul-04 5:19

Axonn Echysttas

13-Jul-04 5:19

Thank you for your answer Heath. I can see why you are a MVP Big Grin | :-D

. The problem is that I`m kind of new to the .Net "peripherical utilities". I've been developing programs in .Net at work for a year, but I never had to distribute one. Now I made a little IRC client at home and I want to deliver it and I have problems...

Not to mention that I don't know what's that XCOPY or "File System Editor" and where I can find them. But I have MSDN and I will search, that's the least of my worries.

First of all... the File System editor can help me? I can add files to my project using that, maybe, but will it register the WinSock OCX control?

Can you tell me if the Windows Installer made be Wise is free?

Thank you, have a nice day Wink | ;)

The Greater Mind Balance

Heath Stewart13-Jul-04 5:24

13-Jul-04 5:24

XCOPY is a program used to copy files and has more features than the simple COPY shell command (it's not a program, but is implemented by the command shell).

The File System editor is a few of the file system in a Windows Installer package. Again, I encourage you to play around with it. It was designed to be simple (overly simple in my opinion, since I've been working with Windows Installer since MSI 1.0 beta).

Wise for Windows Installer is most definitely not free (it's a commercial application; it requires lots of time and money to develop), and you can find more information about it at the link I gave you in my first reply.

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Axonn Echysttas13-Jul-04 5:49

Axonn Echysttas

13-Jul-04 5:49

Hmm... so the File System Editor is included in the Windows Installer package. Can you tell me where I can find that? MSDN is very obscure... I can't find anywhere something that says how to get to the File System Editor.

(Where it is located on the hard drive or where I can find it using menus or stuff like that)

Another question. Would it be enough to use regsvr32.exe to register the winsock ocx on the target machine?

Thanks again Smile | :)

The Greater Mind Balance

Heath Stewart13-Jul-04 6:09

13-Jul-04 6:09

It's part of the Windows Installer project package. Select your Installer project in VS.NET (after adding one, of course), and select View->Editor->File System, or click the "File System Editor" button above the Solution Explorer with your installer project selected (or something in the project).

If you don't want to use an installer, yes, you can run regsvr32.exe on your WinSock OCX to register it.

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