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Please be kind if this is a foolish question or has been discussed ad nauseum, but I can't find it and I don't get it.
As a dyed-in-the-wool C++/MFC programmer, I now have to start usign C#, but of course new programs I write still have to interact with existing C++/MFC programs. The existing C++/MFC programs communicate with each other through Windows messages (mostly WM_USER + xxx, but also sometimes just sending a WM_CLOSE to close each other). They ALSO communicate internally to a given process among threads by using PostMessage() and PostThreadMessage() with user-defined messages.
So, to my questions:
1) Is it true, as I've read in several places now, that the only/best way for a C# application to receive a Windows message is by overriding WinProc? That seems hideous.
2) Is it true, as I've also read, that the only way for a C# application to send a Windows message to another application is by P/Invoke of SendMessage()?
3) Finally, for the communication between threads or windows of a given process. I realize that I can call functions back and forth, use delegates, or whatever, but (pardon my ignorance), that seems very synchronous and painful compared with being able to call PostMessage() or PostThreadMessage() and not have to wait for the receiver to process the message. Is there a better way?
Thanks for any advice.
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larrywph wrote:
1) Is it true, as I've read in several places now, that the only/best way for a C# application to receive a Windows message is by overriding WinProc? That seems hideous.
From what I've done of Windows Programming the answer is yes. Why does this seem hideous to you? Overriding a function seems fairly clean.
larrywph wrote:
2) Is it true, as I've also read, that the only way for a C# application to send a Windows message to another application is by P/Invoke of SendMessage()?
seems like it
larrywph wrote:
3) Finally, for the communication between threads or windows of a given process. I realize that I can call functions back and forth, use delegates, or whatever, but (pardon my ignorance), that seems very synchronous and painful compared with being able to call PostMessage() or PostThreadMessage() and not have to wait for the receiver to process the message. Is there a better way?
Not exactly sure what you're going for here. Perhaps you can provide an example so we can better understand your problem
Jared
jparsons@jparsons.org
www.prism.gatech.edu/~gte477n
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I'm calling a DLL method that has an LPTSTR parameter which may come back with embedded NULLs. After calling the method, I need to parse this parameter and extract the individual "words" into a string array:
[DllImport("myDll")]<br />
public static extern void GetMyWords(StringBuilder result, int size);<br />
<br />
public string[] GetWords()<br />
{<br />
StringBuilder sb = new StringBuilder(1000);<br />
GetMyWords(sb, 1000);<br />
return sb.ToString().Split(new char[] {'\0'});<br />
}
The problem is that the result is somehow truncated after the first word. What should I do to prevent this from happening?
Thanks!
Alvaro
Can I ask you a question?
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Using C#,
How would I refresh the desktop? Say I created a shortcut and it did not show after creation, or if I programmatically changed the desktop path in the Registry and would not appear to change until I logged in again. I want to make these changes appear immediately.
Thanks
Rob
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Just guessing that you are using a windows based OS, the best way i can think of is searching for the correct api call on microsofts website (msdn) then make that call. Your can call the graphics object that draws the desktop and tell it to refresh..but i dont think this would fix the problem. Hope this Helps.
Jesse M.
The Code Project Is Your Friend...
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Thanks,
Yeah, the api calls are weird though because they refresh specific desktop items only like wallpaper, screen, but do not address the path of the virtual folder and items within it. I am sure I will get to the right one.
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Im wondering if one of those calls to the api that refreshes (say the wallpaper) also refresh's other things like links and icons ect.
Jesse M.
The Code Project Is Your Friend...
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I'm working on a program to store my DVD collection, download the cover images, etc. I know programs exist to do this already, but I needed a project to learn C#, so this is it.
I've run into a logic problem when downloading Cast/Crew data from IMDB and storing it. My project uses an XML file to store the collection data, in this format:
<owned>
<movie>
<rating>R</rating>
<id>12345</id>
<title>Movie Title</title>
<year>2003</year>
<length>122</length>
<cast>
<star id="12345">Some Guy</star>
<star id="54321">Some Girl</star>
</cast>
</movie>
</owned>
Right now everything but the <cast>...</cast> information is parsed and stored in a ListView control, which works fine. The problem I'm having is how to store the data so that I can click on a person and see all the movies I have with them in it.
In a language like PHP I'd do an array of arrays with associative key => value pairs, like
Stars = array(
'Star ID' => array(
'Movie ID' => 'Movie Title',
'Movie ID' => 'Movie TItle')
);
And the equivalent in C# seems to be a hashtable, but it won't let me do Hashtable[Key].Add(ID, new Hashtable())
So I guess what I need a multi-dimensional Hashtable? Does anyone get what I'm talking about?
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Why not load the data into a dataset? Once it is in a dataset you can apply filters to limit which rows are displayed. Populate into three tables, one table of movie data, one table of star data and one relational table that ties stars and movies together.
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I like Daniel's suggestion of using a DataSet - there's a lot you could do with it if you chose to use it.
Otherwise, you may want to look at the NameObjectCollectionBase from the System.Collections.Specialized namespace.
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DataSets look good, thanks guys.
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I have a relational Access DB and I am wondering if there is any way to get the schema of the entire database and write it in XML. The second thing I am trying to find out is if it is possible to export the XML schema from this Access DB as an Oracle Script that will build an oracle database with the same relationships as my existing Access DB. Thanks for your help, you guys are lifesavers!
Frank 
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look at the Data COmmandBuilder classes, should provide the schema for u, dunno about oracle as u need a phd (and a small atomic powerplant) to work with it.
leppie::AllocCPArticle("Zee blog");
Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.
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For our Beta builds, I need to run a command line program just before building the main assembly. Yet the only pre-build setting I can find runs it for ALL configurations.
(I modified the utilities in question to accept a parameter of $(configuration name). Of course, this means the utilities have to now be build and for all configurations. Who's the idiot who came up with this limitation?)
Joe Woodbury
When all else fails, there's always delusion.
- Conan O'Brien
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Good idea. Thanks.
Joe Woodbury
When all else fails, there's always delusion.
- Conan O'Brien
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I would like to know if there is any built in function/library in C# which lets me solve the foll. Statistical problem:
Given the mean and the variance of a normal distribution, I want to get the sample points that are arrived at based on the mean and variance.
(Basically some function similar to the Worksheet function NormInv in MSExcel).
Right now I am doing a very kludgy solution where I create an Excel Worksheet function object just to access the function. This makes my application real slow.  Moreover I need this type of evaluation to be done possibly 10,000 times as I am developing some kind of a simulator.
Anybody please help !!!!
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Those methods wouldnt be hard at all to implement in a class or two. In fact thats a good idea for your 1st article here at CodeProject. 
leppie::AllocCPArticle("Zee blog");
Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.
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I'm sure I remember there being a C# math library on the web somewhere - probably not free though and I can't remember what it was called or whether it supported stats.
Ah, just did a search and there's one here: http://www.centerspace.net/products.php?page=3[^]
The stats library is released next month.
Kevin
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Now that kevin mentioned it. Do a search for Math.NET and Euler.NET on SOurceforge, both provide stats functions i think.
leppie::AllocCPArticle("Zee blog");
Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.
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I'm not sure exactly what you are after, but this may help?
using System;
namespace NormInvFunc{
public class Normal
{
private static double Density(double x)
{
double y=Math.Pow (2*Math.PI ,-.5)*Math.Exp(-.5*x*x);
return y;
}
public static double StandardNormal(double x)
{
double [] a=new double[5];
a[0]=.31938153;
a[1]=-.356563782;
a[2]=1.781477937;
a[3]=-1.821255978;
a[4]=1.330274429;
double K=.2316419;
double L=Math.Abs(x);
double nx=Density(L);
double q=1/(1+K*L);
double S=0;
for(int j=0;j<5;j++)
{
S+= a[j]*Math.Pow(q,j+1);
}
double SND=1-nx*S;
if(x<0)
{
SND=1-SND;
}
return SND;
}
public static double StandardNormalInv(double R)
{
double Delta=1;
double X=0;
double Y=0;
do
{
Y=X-(StandardNormal(X)-R)/Density(X);
Delta=Math.Abs (Y-X);
X=Y;
}
while (Delta>.000000001);
return Y;
}
}
}
NB will not return quite as many decimal places as excel.
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I am try to use multi-thread. I use "lock" like this:
class MyClass<br />
{<br />
private object status = null; <br />
<br />
<br />
myfun() {<br />
...<br />
lock ( status ) {<br />
status = new object(1);<br />
}<br />
...<br />
}<br />
}
But it gave me an "ArgumentNullException", anyone know why?
Thanks in advance.
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You need an actual object to lock.
yyf wrote:
private object status = null
Change line into
private object status = new object()<br />
<br />
And everything will be happy. But then again I'm not sure why you're trying to create the object inside of the lock. <br />
<br />
Jared <br />
<a>jparsons@jparsons.org</a><br />
<a href="http://www.prism.gatech.edu/~gte477n">www.prism.gatech.edu/~gte477n</a>
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