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JoeRip wrote: So it stands to reason that you can somehow say "if myException is X, do this" somehow.
You can catch Exception and use the 'is' keyword, ( and hopefully rethrow if it's unhandled ), or you can specify in your catch statemetns what you wan to catch ( better ) Some exceptions have base classes, which you can also catch.
Christian Graus - C++ MVP
'Why don't we jump on a fad that hasn't already been widely discredited ?' - Dilbert
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try
{
// throw specific exception here
}
catch ( KeyNotFoundException ex )
{
}
catch ( InvalidOperationException ex )
{
}
catch ( Exception ex )
{
// all unhandled exceptions go here
}
HTH,
Martin
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Hello, I'm fairly new to the C# world. What am I saying? I'm pretty new to coding all around and I've ran into a problem I have had to luck figuring out. So...
Before you ask, yes I have looked threw articles on the site. But none of them really help me. It is very hard to understand uncommented code at my skill level so it really does no good to me.
My first C# application is a simple RSS reader. I have most of the stuff done for it besides the TreeView. I cannot seem to figure out how to get this TreeView to grab data from my database and then display it in a certain way.
The tree view in the end should look like this:
<br />
TreeView<br />
<br />
|Folder<br />
|-RSS Channel/Feed<br />
|--News Item<br />
Ok so I have three folders in my database: Folders, Feeds, and NewsItems. The folders in the tree view will call the database table Folders, the rss channels/feed will call data from the Feeds table and finally the news items will call data from the NewsItems table.
How would I go about doing this? I have predefined values in all tables in the database, I'm not worried about adding new stuff to it yet and have it update. I just need to get the view to work.
Thanks for any help you can give
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You can read data from the database using the System.Data.SqlClient.DataReader class to read data from your database. Once you have that data, you can create tree nodes from that data, then add those nodes to the treeview. Here's some idea of what this would look like:
SqlConnection connection = new SqlConnection("your connection string goes here");
SqlCommand myCommand = new SqlCommand("Select * from MyTable");
myCommand.Connection = connection;
SqlDataReader reader = myCommand.ExecuteReader();
while(reader.Reader())
{
string nodeText = reader.GetString(0);
TreeNode node = new TreeNode(nodeText);
myTreeView.Nodes.Add(node);
}
connection.Dispose();
myCommand.Dispose();
reader.Dispose();
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Thanks for the help. I've ran into another problem while editing somethings. In order to use this it said to open the database, so I used:
connection.Open();
But it spits out an exception:
System.Data.SqlClient.SqlException was unhandled<br />
Message="An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)"
I don't understand how it is a remote connection if the database is the SQLServer that comes with C# Express 2005. Any ideas?
Thanks again for the help.
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Oh, yes, you'll need to open a connection to SQL. This error occurs when SQL either isn't configured to allow connections to it from remote machines, or your connection string is invalid. Are you sure that connection string works? Try connecting to the database from, say, Sql Management Studio, or some other tool with that connection string to verify your connection string works.
p.s. judging by the error, named pipes might not work in this scenario. Try TCP.
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Yup, 100KB app, 25KB of pictures, no sounds.
When it loads it imediatly takes up 9MB, now i know thats not alot, but where is it going? When the app loads it displays an empty listbox with 4 colums, two combo boxes with 10 items in, 5 buttons, and a text box.
It also creates 2 bools and a ListViewItem array, all empty. (The array is not given a size, just defined)
It does no processing, doesn't load any files, doesn't connect to the internet, until the user does something.
So err, why is it using so much and how do i fix it?
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Well, that's the way things are nowadays, your first line of code is very expensive
(whatever it contains).
The good news is you can add 100,000 lines of code and still may need no more than say 50 MB
of memory.
Luc Pattyn
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Indeed, i just checked a test app i made, which has one button, a text box, with just 100 lines of code total. It also yoinks itself 9MB.
It just seems a bit of a waste really.
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Sure it is, but then those tons of megabytes are sitting there anyway, so why not fill them ?
(Same holds true for disks).
Luc Pattyn
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That's the way .NET works. It allocates that "much" memory without actualy needing it. Reason is performance. Allocating one big block is more efficient then allocate many little blocks of memory. When later you need memory, "allocating" is as fast as changing one pointer. IIRC .NET does release this extra memory when OS is getting low on memory. No big deal in 99% of cases.
"Throughout human history, we have been dependent on machines to survive. Fate, it seems, is not without a sense of irony. " - Morpheus
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As has been said, nothing to fix. Your usage is not linear, adding anouther 25kb of pictures will probably have no effect on your program size at all.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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Ah, you learn somehting new every day. Im just suprised i never noticed this before, i've been doing it long enough. And with 2GB of RAM, it really doesn't make any difference.
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We are using Visual Studio .NET 2003 ,C# and MS SQL SERVER 2000.
Ours is a Web Application. Now i need to develop some reporting application with which our power users or executives should be able to pull data and make decisions.
can I integrate that with my web application?
What are options here? why?
My visual Studio.net 2003 has crystal reports but asking me for registration. do i have buy a different license for it?
Is crystal reports and Business objects same? and what version should i select?
Any help on this would be really appreciated.
Thanks.
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Hi everyone,
Could anyone tell me the best book available for:
1. OOPS
2. C# 2.0
2. .NET Framework 2.0
I am new to .NET and C# (and programming). I have been working on VB.NET 2003 for the past 6 months and would like to learn more about .NET 2.0, OOPS, and .NET Framework 2.0. Any information that you guys would like to share would be appreciated.
Regards,
Blumen
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It does not fit in any of your 3 categories but I found Professional C# 2005 (Wrox) an excellent resource.
led mike
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Professional C# 2005 is not a professional level book. Sure it isn't an intro to programming but I am looking for more in books with the professional title.
On two occasions I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage
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I hated Wrox. I was not surprised that they went broke. Overthick books full of useless code listings ( i.e. listings of boiler plate code, etc ).
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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Ennis Ray Lynch, Jr. wrote: Professional C# 2005 is not a professional level book.
I don't understand that statement. For example when I used the Remoting Chapter, I found the information was complete and presented in a logical fashion. What do you mean by "not a professional level"?
led mike
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Implies years of industry experience and the ability to search on the web and read API references. A book with the title Professional should understand that focus on applications of the new technologies in difficult and new ways which would expose a professional to A) Solid reference to advanced topics and B) Provide exposure to methodology
While definately not intro to programming the book is an intro to C#.
File Not Found
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Ennis Ray Lynch, Jr. wrote: A) Solid reference to advanced topics and B) Provide exposure to methodology
I guess we will just disagree. The book does A and B has nothing to do with C#.
led mike
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I think B is critical because without a second, third, fourth voice everything becomes an echo chamber. Perspective from experience is crucial in a professional level book.
As for A your definition of coverage and advanced topics may be different from mine. I often say I could never be a teacher because I would fail all the students.
File Not Found
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Ennis Ray Lynch, Jr. wrote: I think B is critical because without a second, third, fourth voice everything becomes an echo chamber. Perspective from experience is crucial in a professional level book.
Not sure what all that means but if you read the back cover synopsis you would not expect to see any echo chamber stuff in there.
Ennis Ray Lynch, Jr. wrote: As for A your definition of coverage and advanced topics may be different from mine.
Well I am not comparing this to something like Advanced Windows (Richter). The back cover synopsis of the book it does not claim to be anything like that. The only part of the back cover I disagree with is "so that you can begin programming like an expert right away", no book should claim that. In this case it covered topics like Remoting and EnterpriseServices which I used and found them to be "exactly" what I needed. First a simplified discussion and example leading to more complex aspects of the topic resulting in coverage of a variety of implementation options. Please note, that does not mean "in depth". The synopsis also says "help you gain a well rounded understanding", which I believe is accurate.
led mike
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For OOP, I'd read some online info, it's not that hard, and if you've been using VB.NET, you've been using it.
For C#, I'm not sure of any good 2.0 books, I have the language spec, but it's hardly light reading. I'd look for a good C# book, and then learn the 2.0 features from there.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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First I want to congratulate you on choosing to travel the path of OOP instead of reading fat books that tell you how not why. I like Robert Martin however his C# book is not that overwhelming but check out his web site www.objectmentors.com and when you have tired of that try www.oodesign.com.
I like Apress books for C# I used Pro C# 2005 and the .NET 2.0 Platform, Third Edition which was not as good as his 2003 Book but it is a pretty solid reference.
Foundations of Object-Oriented Programming Using .NET 2.0 Patterns by Christian Gross is a great book on OOP and Patterns you may want to look at I have found it quite good but it is complex. Beyond that may I suggest some O'Reilly books on the framework and c#.
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