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Please someone explain me about:
1. ActiveX dll's get registered in the registry. How about c# dll's?
2. Is it possible to invoke a object from a dll sitting on another machine...
something like we use in VB
ex. set obj = Createobject(progid, machinename)
I am sorry, if I my questions are meaningless. Please be patient and explain me so that I can understand.
THanks in advance.
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All CLR Asseblies are self-contained, meaning that all information is stored within the Assembly itself. COM objects store information in the registry as well as in the objects type library. C# and all other .Net languages store information in the Metabase which is stored in the dll itself. This is why we can't do late binding with .Net languages.
If you do need your DLL registered as a COM object so that you can use it in other languages such as VB6 or Delphi; there is a utility that ships with Visual Studio.Net that will create a type library for your objects and register them in the registry.
You can find more information on this process in the Visual Studio help files.
Hope this helps you.
-V-
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I notice in a lot of C# code that "this.SomeVar" is used when the "SomeVar" could be called directly.
I removed the "this." from a WebApplication and it seemed to work OK 
What is it doing and why is it here? Is it the same as the C++ "this->"?
Thanks
Note I only used C# for a day so if this is a stupid question I am sorry.
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My code looks like this (before cleaning, anyway) because I usually manage to forget the names of member variables. Typing "this." brings up a list of member variables, letting me search for my member variable's name without having to change my place in the code. So, short answer - laziness - at least in my case
--
Russell Morris
Georgia Institute of Technology
"Lisa, just because I don't care doesn't mean I'm not listening..." - Homer
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Hi!
The [this] keyword is used so that you can refer to a member variable instance without accidently calling another variable by the same name. Take this example:
class MyExample
{
private string value = "";
public string Text
{
get
{
return this.value;
}
set
{
this.value = value;
}
}
}
Now personally I would not have written code like this, but there could be a time when something similar occurs. In this example, value is the variable name sent in though the Text Property and can't be renamed. Since I have an internat member called value, the only way that I can communicate with it is with the [this] call, which tells the compiler you were talking about the global instance and not the system local instance.
Using the [this] statement is not required by any means, but can help tell other developers that you are:
A. Using a member property and
B. There can not be a conflict in local naming.
I hope this helps.
-V-
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I have an a final Assignment due for a CS140 course and I really need some help. My professor puts the assignments on the web and the URL for the one I'm having trouble with is: http://www.hello-world.com/MC/CS140/Assignments/A8_sort.htm. It involves having to sort 8 names. I can't get my program to print out an array at all. I'm getting a variety of errors too. If anyone could help me, I would really appreciate it. I'll email you the work I've done so far. I'm kind of desperate here since the assignment is due BY December 18, 2000 so can someone PLEASE help me. Thanks!
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Okay i have not looked into this, but i figured maybe
someone else has. Will we able to embed C# directly into
ASP pages, like we can embed java into jsp. If so
will ASP have a servlet analog like jsp does.
I am learning jsp now and find it pretty easy, so i figure
if C# is able to do the same thing as java does for JSP
then it will make asp easier. I dont mean raw asp, i mean
have a strongly typed language for asp.
thanks
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Actually any language that is supported under .NET will work within ASP+ pages. This includes both Microsoft's C#, VB (no more VBScript, you get the whole thing instead), and Javascript. Also many other third parties are working on other .NET compatible versions of their languages (such as Cobal, pascal, Fortran, etc.).
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And to note another part to his question...
As required by the CLR Specification, all DotNet languages are strongly typed, so ASP.Net will act like your JSP.
-V-
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Can I create custom user interface in C#, for instance like MS Office2000, similarly as in Visual C++.
Mike
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Mike,
C# is a language, so it really doesn't define what you can and can't do as far as interface design. Microsoft with the .Net runtime has made all programming languages equally powerful, so anything you can accomplish in one language, you can reasonably expect to accomplish in any other .Net compatible language.
Microsoft is pretty hard-core about C#, so to answer your question, yes, you can make sophisticated UIs like you find in Office in C#. You can also make those UIs in VB, in Cobol, in Eiffel, etc.
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Hi Mike,
If you are talking about writing a Windows Program than you just need to look up examples on System.WinForms. Since Microsoft is only documenting DotNet in C# you should be able to find lots of information on this.
-V-
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I am dying to get my hands on the C#. My question is whether the latest or up coming installments of MSDN Universal Subscription will have beta version of C#.
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The material is already available for download, I'm sure that it will be included in the next round of MSDN Universal distributions too. For more information on this, check out this thread on CodeProject.com
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I am not sure if it has been said that C# has been submitted to ECMA or will be submitted to ECMA but I did a quick search of the internet and I get the impression that C# has not (yet) been submitted. Something that I found interesting is that Sun has submitted Java to ECMA and Microsoft has submitted JScript. I do not find anything in the ECMA web site about Java though. If, however, Netscape has submitted Java then it makes sense to me that Microsoft will submit C#.
ECMAScript is evidently a standardized JavaScript/JScript.
See: http://www.ecma.ch/
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I guess it has been submitted (or atleast in the process)and they are reviewing it. But I dont know on what stage it is, but atleast EMCA are doing some work on c#. Not only C#, but also CLI. I guess one day or other both C# and CLI(Common Language Infrastructure, I guess it is same CLR) will be a standard. May be I'm too optimistic! 
Refer to their website!
http://www.ecma.ch/ecma1/news/news.htm
*note if that link doesnt work, search "C Sharp" (not C#)
on their site.
regards
Ravi
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Hi Ravi,
Yes C# has been sent and accepted as a Standard with Microsoft and IBM on the board for the committe. Also to note that JScript is also a full programming language now as well with JScript.Net
-V-
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I guess no one can realy decide before he has a compiler at hand.
MS gave those at PDC, so how come they are not giving it away to everyone?
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Depends whether you are asking "Is C# the mythical 'Cool' that we all heard rumours about last year", or "Is C# a good language".
According to the recent poll (http://www.codeproject.com/script/poll/detail.asp?topic=71) most people felt C# was definitely uncool - but it is really hard to judge until you've used the new IDE, written some apps and compared the functionality. Personally I feel it will be kinda nice to drop back to C# to write a COM client, then maybe do a little VB to whip up a neat UI, and then roll up the sleaves to get some hard core C++ going - all working together in the same environment. I think everything simply needs to be put into perspective.
As to whether C# is the Cool project, I was talking to the MS guys and got a definite 'sort of but not quite'. Cool was the name for an entire new technology on which .NET was based. C# is a major part of this, and so in a way C# was part Cool, but Cool was more than C#. At least that was my understanding...
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C# is definitely cool to program in. BTW, you won't need to drop back to VB to do UI. C# (as well as managed C++) gets the same RAD support that VB has in VS.NET. Check out the following code I wrote in about a half hour to display three jpg images. Note, this code probably wouldn't be too hard to duplicate in VB, but try this in VC++ using Win32 API  NOTE: the use of XML comments. The compiler supports stripping these out into an XML document like so:
<makefile>
all: MyPhotoAlbum.exe
MyPhotoAlbum.exe: MyPhotoAlbum.cs
csc /debug+ /doc:MyPhotoAlbum.xml /t:winexe \
MyPhotoAlbum.cs /r:system.dll \
/r:system.drawing.dll /r:System.WinForms.dll \
/r:System.Data.dll /r:Microsoft.Win32.Interop.dll
namespace CSharpApp
{
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Collections;
using System.ComponentModel;
using System.WinForms;
using System.Data;
///
/// Class representing my application's main window
///
public class MainWindow : System.WinForms.Form
{
/// Required designer variable
private System.ComponentModel.Container components;
private System.WinForms.Button m_button3;
private System.WinForms.Button m_button2;
private System.WinForms.Button m_button1;
///
/// IVar to hold reference of bitmap to paint
///
private System.Drawing.Bitmap m_bitmap;
private System.Drawing.Bitmap m_bitmap1;
private System.Drawing.Bitmap m_bitmap2;
private System.Drawing.Bitmap m_bitmap3;
private System.Drawing.Point m_orgBitmap;
public MainWindow()
{
//
// Required for Win Form Designer support
//
InitializeComponent();
//
// TODO: Add any constructor code after
// InitializeComponent call
//
try
{
m_bitmap1 = new Bitmap(@"c:\images\A.jpg");
m_bitmap2 = new Bitmap(@"c:\images\B.jpg");
m_bitmap3 = new Bitmap(@"c:\images\C.jpg");
}
catch (Exception e)
{
MessageBox.Show(e.ToString(), "Bummer!",
MessageBox.IconHand);
}
m_orgBitmap = new Point(10, 60);
}
///
/// Clean up any resources being used
///
public override void Dispose()
{
base.Dispose();
components.Dispose();
}
///
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor
///
private void InitializeComponent()
{
this.components =
new System.ComponentModel.Container();
this.m_button1 = new System.WinForms.Button();
this.m_button2 = new System.WinForms.Button();
this.m_button3 = new System.WinForms.Button();
this.AutoScaleBaseSize =
new System.Drawing.Size(5, 13);
this.Text = "My Photo Album";
this.BackColor = System.Drawing.Color.Blue;
this.ClientSize = new System.Drawing.Size(586, 445);
m_button1.Location = new System.Drawing.Point(8, 8);
m_button1.BackColor =
System.Drawing.SystemColors.ControlLight;
m_button1.Size = new System.Drawing.Size(75, 23);
m_button1.TabIndex = 0;
m_button1.Text = "Bitmap 1";
m_button1.AddOnClick(
new System.EventHandler(ButtonClickHandler));
m_button2.Location =
new System.Drawing.Point(104, 8);
m_button2.BackColor =
System.Drawing.SystemColors.ControlLight;
m_button2.Size = new System.Drawing.Size(75, 23);
m_button2.TabIndex = 1;
m_button2.Text = "Bitmap 2";
m_button2.AddOnClick(
new System.EventHandler(ButtonClickHandler));
m_button3.Location =
new System.Drawing.Point(200, 8);
m_button3.BackColor =
System.Drawing.SystemColors.ControlLight;
m_button3.Size = new System.Drawing.Size(75, 23);
m_button3.TabIndex = 2;
m_button3.Text = "Bitmap 3";
m_button3.AddOnClick(
new System.EventHandler(ButtonClickHandler));
this.Controls.Add(m_button1);
this.Controls.Add(m_button2);
this.Controls.Add(m_button3);
}
protected void ButtonClickHandler(object sender,
System.EventArgs e)
{
// Rectangles to store regions to invalidate
Rectangle rectPrev =
new Rectangle(m_orgBitmap, new Size(0,0));
Rectangle rectCurrent =
new Rectangle(m_orgBitmap, new Size(0,0));
// Grab current bitmap's size
if (m_bitmap != null)
rectPrev.Size = m_bitmap.Size;
// Select appropriate bitmap based on the sender
if (sender == m_button1) {
m_bitmap = m_bitmap1;
}
else if (sender == m_button2) {
m_bitmap = m_bitmap2;
}
else {
m_bitmap = m_bitmap3;
}
// Grab new bitmap's size
if (m_bitmap != null)
rectCurrent.Size = m_bitmap.Size;
// Create region, union of both rectangles
Region region = new Region(rectPrev);
region.Union(rectCurrent);
// Invalidate the combined regions
this.Invalidate(region);
}
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
// Draw background
g.FillRectangle(new SolidBrush(Color.Blue),
e.ClipRectangle);
//Render bitmap image
if (m_bitmap != null)
g.DrawImage(m_bitmap, m_orgBitmap.X,
m_orgBitmap.Y);
}
// The main entry point for the application.
public static void Main(string[] args)
{
Application.Run(new MainWindow());
}
}
}
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WAH! What happened to my spaces?
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It's good ol' HTML doing its thing...
I think you can avoid it by simply wrapping the code inside PRE tags, like this:
< pre>
// some code
int n = 70;
</pre>
Which will look like this:
int n = 70;
Much better, don't you think? And thanks for the sample code. It's amazing how similar it looks to Java.
Regards,
Alvaro
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