Updating Listbox Items - C# Discussion Boards

StealthyMark26-Jul-03 14:14

26-Jul-03 14:14

In the DateTime structure, one Tick always equals 100 ns (100 nanoseconds = 0.1 mikroseconds = 0.0001 milliseconds). But as you said, the actual resolution is somewhat lower.

getting the name of a passed parameter

Rbledwards25-Jul-03 11:42

Rbledwards

25-Jul-03 11:42

I have a reporting interface that generates 100 or so reports. Each report uses a varying combination of 11 total parameters (from 0 - 4 at most). So I could have:

Report report = new Report(StartDate, EndDate, NameID, LocID) //or just
Report(StartDate, NameID) //or
Report()

My problem is: how do I get my constructor to accept the parameters and know which ones were passed without overloading it a gillion times. Is there a way to a generic type parameter and get the actual name of the parameter passed? If I have the name of the parameter I can cast to the right type. I could even create a hashtable with all my parameter names, types and build my AddParameter method off of the parameter name.

Actually If I can get the name of the parameter, and I know the most that will be passed is four, five constructors and be good to go...I think.

Is this possible?

Robert

Re: getting the name of a passed parameter

albean25-Jul-03 11:48

albean

25-Jul-03 11:48

Why not just pass it a collection or array that contains your "parameters".

Re: getting the name of a passed parameter

Rbledwards25-Jul-03 12:25

Rbledwards

25-Jul-03 12:25

Excellent idea. Obviously never thought of it.

Re: getting the name of a passed parameter

Daniel Turini25-Jul-03 11:49

Daniel Turini

25-Jul-03 11:49

Besides albean suggestion, which makes it very flexible for extending parameters, you can always set properties of a class and pass this class as a parameter to your Report constructor.

Acting as a substitute for God, he becomes a dispenser of justice. - Alexandre Dumas

Re: getting the name of a passed parameter

Jim Stewart25-Jul-03 11:54

Jim Stewart

25-Jul-03 11:54

Martin Fowler had a solution for this type of problem in Refactoring with Introduce Parameter Object (p. 295). The concept is to "Create a new class to represent the group of parameters you are replacing."

ReportParams rp = new ReportParams (StartDate, EndDate, NameID, LocID);
Report report = new Report (rp);

Your new parameter object could have all the permutations of parameters and remove those details from the Report class.

α.γεεκ

Fortune passes everywhere.
Duke Leto Atreides

Re: getting the name of a passed parameter

Rbledwards25-Jul-03 12:26

Rbledwards

25-Jul-03 12:26

Off to Amazon.com I guess. Thanks for the tip.

Updating Listbox Items

monrobot1325-Jul-03 10:37

monrobot13

25-Jul-03 10:37

Hi Yallz,

I have a list box that you can edit the items in (click a button, and it pops up a form so you enter the info you want), the problem I'm encoutering is that once the user presses OK on the edit form the listbox isn't update with the new informatin. Is there anyway to update a listbox item without removing it and then adding it back?

Thanks!

- monrobot13

Re: Updating Listbox Items

albean25-Jul-03 11:37

albean

25-Jul-03 11:37

Are you doing something like this in your click event:

MyForm f = new MyForm();
f.Show();

If you are then your problem is you are getting a NEW form each time with an empty list.

Try hiding the listbox form when you are done with it. In the button click event unhide it.

Re: Updating Listbox Items

monrobot1326-Jul-03 6:21

monrobot13

26-Jul-03 6:21

That's not it. I actually serialize all the listbox items when the form is closed and then deserialize them when it's loaded. When I do this it does show the new information.

When you add an item to a listbox it call's it ToString function to get the text to display. I want to update the text that is being displayed without removing and readding the item.

- monrobot13

Re: Updating Listbox Items

StealthyMark28-Jul-03 0:06

StealthyMark

28-Jul-03 0:06

Don't use ToString().
Add the item itself, or better yet use databinding to display a complete collection. When you edit the collection entry, the listbox is updated (possibly after a call to Refresh()).

equivalent of this.DoEvents() ????

LongRange.Shooter25-Jul-03 10:33

LongRange.Shooter

25-Jul-03 10:33

Does anyone know what the C# WinForm equivalent is of the old VB6 DoEvents() method on forms???

This is the process where a tight loop will allow the form to process events before going back into its' loop.

Thanks!

_____________________________________________
_{The world is a dangerous place.
Not because of those that do evil,
but because of those who look on and do nothing.}

Re: equivalent of this.DoEvents() ????

J. Dunlap25-Jul-03 10:43

J. Dunlap

25-Jul-03 10:43

Application.DoEvents(). But in many cases it's better to use multiple threads.

"Blessed are the peacemakers, for they shall be called sons of God." - Jesus

"You must be the change you wish to see in the world." - Mahatma Gandhi

Re: equivalent of this.DoEvents() ????

LongRange.Shooter26-Jul-03 3:21

LongRange.Shooter

26-Jul-03 3:21

Well...I have the methods I am calling broken out into a DLL. And I did find the Application.DoEvents() to be fairly non-responsive. (2 or 3 button clicks to end the process)

But I'm not really familiar with spawning threads in a WinForm client. What are the basic steps I would need to do to make the component an independant thread? Or if you know of a tuturial...?

Thanks,

MJ

_____________________________________________
_{The world is a dangerous place.
Not because of those that do evil,
but because of those who look on and do nothing.}

Re: equivalent of this.DoEvents() ????

J. Dunlap26-Jul-03 11:51

J. Dunlap

26-Jul-03 11:51

There's sure to be one on CodeProject somewhere, but here's a brief example:

//assumes that the method you want to start the thread on 
//is named "ThreadMethod".
 
//in class
using System.Threading;
Thread thread=null;
 
//in method that starts thread
thread=new Thread(new ThreadStart(this.ThreadMethod));
thread.IsBackground=true;
thread.Start();
//optional - make thread start working before this method completes
Thread.Sleep(0);

"Blessed are the peacemakers, for they shall be called sons of God." - Jesus

"You must be the change you wish to see in the world." - Mahatma Gandhi

MessageBoxIcon

albean25-Jul-03 9:37

albean

25-Jul-03 9:37

Does anybody know how I can access the MessagBoxIcons directly? I want to stick one on a Form (not a MessageBox). Is there some sort of internal imagelist in the Framework?

Re: MessageBoxIcon

Alex Korchemniy25-Jul-03 9:50

Alex Korchemniy

25-Jul-03 9:50

If you use Reflector to decompile the .net framework you will see that the native MessageBox method is called. The MessageBoxIcon is just an enum. The value is passed to the native func as an int.

I suggest opening the native lib with VS.NET and ripping the icons.

Re: MessageBoxIcon

dynamic25-Jul-03 9:50

dynamic

25-Jul-03 9:50

in this folder : ( where your drive goes inplace of " D " )
D:\Program Files\Microsoft Visual Studio .NET\Common7\Graphics\icons

there you will find them , listed under " Computer " i think , although they are embeded in .net for the messagebox's

Vb:

<font color="blue">Public Function</font> TwinsOnWay(<font color="blue">ByVal</font> twins <font color="blue">As String</font>) <font color="blue">As String <br>     Select Case</font> twins<br>         <font color="blue">Case</font> "Gender" <br>             <font color="blue">Return</font> "Two Girls" <br>     <font color="blue">End Select <br> End Function</font> <br>

Re: MessageBoxIcon

Kastro25-Jul-03 9:52

Kastro

25-Jul-03 9:52

The icons are not part of the .NET Framework. The internal implementation of MessageBox.Show just calls the Platform SDK function MessageBox, passing a flag value that specifies the icon you want displayed. The icons themselves are stored as resources in user32.dll.

Get/set method for an array?

frogb0x25-Jul-03 9:35

frogb0x

25-Jul-03 9:35

Hey all,

How can I create a get/set method that returns the Nth item of an array?

Re: Get/set method for an array?

Alex Korchemniy25-Jul-03 9:54

Alex Korchemniy

25-Jul-03 9:54

What do you mean?

The easiest way is to just do array[x]

What exactly are you trying to do?

Re: Get/set method for an array?

frogb0x25-Jul-03 10:00

frogb0x

25-Jul-03 10:00

Well, I have a class Foo(). Inside Foo is a private array of another class, Bar().

public Foo()
{
private Bar[] myBars = new Bar[10];
}

When I instantiate Foo, I need to be able to assign a value to the array of Bars:

myFoo.myBars[n].someValue = 10;

So how can I do this?

Re: Get/set method for an array?

Kastro25-Jul-03 10:00

Kastro

25-Jul-03 10:00

Such a property is called an indexer. You can read a tutorial on them in the MSDN documentation (under "indexers->tutorial (C#)")The following is an example...

public class MyArray {
 
    ...
 
    public Object this[int index] {
        get {
            return _Items[index];
        }
        set {
            _Items[index] = value;
        }
    }
 
    private Object[] _Items;
 
}

System.Drawing from web

Steve McLenithan25-Jul-03 9:19

Steve McLenithan

25-Jul-03 9:19

I am having trouble figuring out how to progamatically save images from a website using this class. I tried this:

private void SaveImages(string url)
{
	int s = Application.StartupPath.IndexOf("bin\\Debug");
	Bitmap img = new Bitmap(url);
	img.Save(Application.StartupPath.Remove(s,9) + "image1.gif", ImageFormat.Jpeg);
}

I get this error message though:
URI formats are not allowed.

Do I have to use a stream object to do this? If so how do I load the remote image into the stream?

Thanks cause I'm lost;)

Steve
McLenithan

Is Bert Evil? | Homer: "Hello, operator, gimme the number for 911!"

Re: System.Drawing from web

dynamic25-Jul-03 9:28

dynamic

25-Jul-03 9:28

here ya go , by chance i built this a few days ago to help someone on another forum Smile | :)

C#:

<font color="blue">private</font> <font color="blue">void</font> button1_Click(<font color="blue">object</font> sender, System.EventArgs e) <br> { <br>        System.Net.WebClient web=<font color="#0000FF">new</font> System.Net.WebClient(); <br> 	System.IO.StreamReader sr=<font color="#0000FF">new</font> System.IO.StreamReader(web.OpenRead("http://www.codeguru.com/forum/images/icons/icon8.gif")); <br>        System.Drawing.Image i=System.Drawing.Image.FromStream(sr.BaseStream); <br>        <font color="DarkGreen">//////////////////////////////////////// </font><br>        i.Save("D:\\myImage.gif"); <font color="#008000">// save the image ( in this case a gif )</font><br> 	<font color="#008000">//////////////////////////////////////// </font><br> 	sr.DiscardBufferedData(); <br> 	sr.Close(); <br> 	web.Dispose(); <br> } <br>

hope it helps

Vb:

<font color="blue">Public Function</font> TwinsOnWay(<font color="blue">ByVal</font> twins <font color="blue">As String</font>) <font color="blue">As String <br>     Select Case</font> twins<br>         <font color="blue">Case</font> "Gender" <br>             <font color="blue">Return</font> "Two Girls" <br>     <font color="blue">End Select <br> End Function</font> <br>

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