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I will surely have a look at it 
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Hi,
In MFC I will often create a UI thread and use it as a worker. I do this because I find the message queue that comes with the UI thread to be very handy for recieving messages in order. When it gets a message it does some work. I also use it to aviod race conditions, i.e. I can have many threads sending messages to the queue and MFC/Windows handles the "Reader Writer" issues of the queue.
What is the equivilant of this in C#? Is there a ready made thread with a message queue where all I would have to do is wait (sleep) until a message arrives?
Thanks.
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How to turn off computer on Win98,Me,2000,nt and XP ?
Greetings
S_W
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I don't know if there is a .NET Framework way of doing it, but you could use the ExitWindowsEx[^] API.
"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
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The button on the front?
Works with Linux too!
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Try a class from mentalis.org:
WindowsController[^].
There is an article on code project about shutting down the computer (I needed it yesterday): Timer Computer Shutdown[^]
Hope this helps,
Nathan
---------------------------
Hmmm... what's a signature?
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You can also do it with WMI Script
Set colOperatingSystems = GetObject("winmgmts:{(Shutdown)}").ExecQuery _
("Select * from Win32_OperatingSystem")
For Each ObjOperatingSystem In colOperatingSystems
ObjOperatingSystem.Win32Shutdown(1)
Next
Save this as .vbs file and run it.
you can also reboot with this script.
'Reboot computer script.
strComputer = "."
Set objWMIService = GetObject("winmgmts:" & "{impersonationLevel=impersonate,(ShutDown)}!\\" & _
strComputer & "\root\cimv2")
Set colOperatingSystems = objWMIService.ExecQuery("Select * From Win32_OperatingSystem")
For Each objOperatingSystem In colOperatingSystems
objOperatingSystem.Reboot()
Next
Bo Hunter
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Does anyone know how to pass an array of strings using unmanaged code? I'm attempting to use unmanaged code to execute an external application with arguments, for example:
c:\matlab\bin\matlab.exe arg1 arg2
The code works fine when arg1 is substitued for a single space character, and matlab executes as if no arguments were passed in. However when arg1 and arg2 are string objects (containing meaningful arguments) in an array of strings, an exception is raised, stating:
"Object reference not set to an instance of an object"
The code which makes the call to the unmanaged code is basically:
public class Win32Wrapper
{
[DllImport("PFA_Win32.dll", EntryPoint="RunExternalApplication", CharSet=CharSet.Ansi)]
private static extern int RunExternalApplication(String application, String[] arguments);
public int RunApplication(String application, String[] arguments)
{
int result = RunExternalApplication(application, arguments);
return result;
}
}
The unmanaged code, written in C++, looks something like:
extern "C" PFA_WIN32_API int __stdcall RunExternalApplication(const char *app, const char *const *argv)
{
return _spawnv(_P_NOWAIT, app, argv);
}
I'd be most appreciative if anyone has done anything similar to this, or can see any flaws in the code.
Thanks
Ash
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I read this on RSS Bandit (GotDotNet) forum.[^]
Question: still does not have any idea where the huge memory use really take place. Readed somewhere, that usage of IE as an embedded control needs additional 12-15MB, but where is the other 70% used? Anyone had any idea? If I build a simple form with only one button it needs at least 15MB RAM, why is it so havy?
I am just curious, anybody know the answer?
Never take a problem to your boss unless you have a solution.
This signature was created by "Code Project Quoter".
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Kant wrote:
I am just curious, anybody know the answer?
Yes: people doesn't know the difference between the used memory and the working set size of a software.
What task manager is showing you is roughly the working set size. It's a very hard and time consuming thing to determine the real memory use of a program, specially if it uses GC.
Each thread on a .NET application receives a 1MB virtual stack. Notice the "virtual" word, it means that it can use up to 1MB of stack space, but it could be (and probably is) using even under 1Kb of this space. The memory is only drawn for Windows when is needed.
So, a simple .NET application may have a few threads for housekeeping, like GC, so, even the simplest .NET application can show a large number on Task Manager.
Most GC preallocates some memory for its use, and the .NET Fx's one is no exception.
Kant wrote:
Actually she replied back to me "You shouldn't fix the bug. You should kill it"
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Off topic
Daniel, I read somewhere in the net about a memory leak caused by processor intensive applications.
For ex. in an app, if there are some processor intensive operations along with some non-trivial memory allocations, tehre is a chance that because of the processor intesive nature, the GC might not have a chance to deallocate, 'cause GC runs as a low priority thread.
Is there any truth to this.
Thanks,
Kannan
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Kannan,
Surely what you're describing is not a memory leak, it's a situation where collection is postponed until a process of indeterminate time reduces it's processing use sufficiently.
I'd describe that as thrashing rather than leaking... 
You reckon?? 
Shaun
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IrvTheSwirv wrote:
I'd describe that as thrashing rather than leaking
There have been some instances where gc does leak memory, check James post below, I was actually more thinking about the scenario and possiblity of such occurance.Imagine having a real-time app. which reads tons of data and displays them in a chart in several windows, this requires frequent memory allocations and is also processor intensive.
Cheers,
Kannan
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Kannan, (my neighbour got same name )
I ran across this info on FogCreek site.
Monitor memory leakage[^]
Hope this info helps.
"I think anybody who doesn't think I'm smart enough to handle the job is underestimating." George W. Bush
--U.S. News and World Report, April 3, 2000
This signature was created by "Code Project Quoter".
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Thanks Kant, I will have a look into this.
Cheers,
Kannan
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There is also a bug in .NET 1.0 where the GC would fail to free memory more than 8MB was allocated. Typically you'd see this when you have a large struct and create a large array of them.
I'm not wording that description correctly, but it isn't a problem you'd often see unless you were doing long [] arr = new long[int.MaxValue] or something like that.
Gah, I just can't find the right words 
[edit]Forgot to mention that this is supposed to be fixed in .NET 1.1[/edit]
James
"I despise the city and much prefer being where a traffic jam means a line-up at McDonald's"
Me when telling a friend why I wouldn't want to live with him
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Kannan Kalyanaraman wrote:
Daniel, I read somewhere in the net about a memory leak caused by processor intensive applications.
For ex. in an app, if there are some processor intensive operations along with some non-trivial memory allocations, tehre is a chance that because of the processor intesive nature, the GC might not have a chance to deallocate, 'cause GC runs as a low priority thread. Is there any truth to this.
What you say have some logic, but I doubt it occurs in real world code. Sure, if you set a thread's priority as "real time", then Windows won't switch from that thread and you may have the mentioned behavior. But, in any other circumstances, GC should be able to run and fulfill memory requests.
Kant wrote:
Actually she replied back to me "You shouldn't fix the bug. You should kill it"
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I think making the thread's priority "real-time" is not recommended, as it affects the OS performance. Anyway, thanks for the clarification
<edit>
Another possible solution to getaway from this scenario (if one exists) is by calling GC's collect method, at predetermined intervals during an apps' life-cycle.
I'm not thinking about using this for normal apps, but for special case apps which use more processor + memory (for ex. a server, or a real-time app. which plots graph from huge data).
</edit>
- Kannan
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Daniel Turini wrote:
Notice the "virtual" word, it means that it can use up to 1MB of stack space, but it could be (and probably is) using even under 1Kb of this space.
Learned to something new.. Thank you.
More you deliberate, more the chances of error.
This signature was created by "Code Project Quoter".
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I have an application that relies on assembilies. The application has an interface defined and when an assembly is loaded checks to see if the class loaded implements the interface. The problem is that the interface is defined in one folder and the assembly is defined in another folder (the assembly folder is not a sub-folder of the first, however I might make it a sub-folder later on. Would that make a difference??). I am little unsure on how to do this. Implementing the interface is where I get stuck:
dir A:
public interface Drivers{}
public class DriverManager{
//verifies that the assembly loaded implements interface Drivers
}
dir B (contains the Assembly):
public class Driver1 : Drivers (how do i reference the interface here???)
{}
The problem is that I cannot get the class Driver1 to compile because it cannot find the interface Drivers due to the fact that Drivers resides in a different directory.
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It has nothing to do with the directory.
namespaces is the key. If you were going to implement the
IDisposable interface how would you be able to do that if that
were the case?
If it is in a different namespace then add the using MyInterfaceNamespace
or use the full namespace and interface name were you declare the interface.
Bo Hunter
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I did include the the namespace with using. When I include all the files in the same directory. I am able to get it to compile. Is there a path I need to set like in Java?
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I can see how you might not be able to get it to RUN but I'm not sure about the compile part...
Quick checklist for ya!!
1) 3 projects (Interfaces, Implementer of interfaces, User of interfaces)
2) All projects loaded in a single solution
3) Implementer and User have project based references to Interfaces.
The load methods of assembly generally require the path to be specified or that the loaded assembly be "relative" to the callers assembly!
More Info!
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I added the two projects to the same solution and referenced one to the other. I use the Loadform method and pass the entire path of the dll. In fact, the interface is in the same namespace as the class that trys to implement that interface. But the that class is part of an dll that depends on the host application (where the interface resides) and is in a different directory. Even when using Microsoft Intellisense, it is not able to detect that the interface and class are in the same namespace (I do include using statement in class definition). I am not sure if its because the two files are in separate dir or in different projects.
I just gave the Interface and the implementer of the interface different namespaces and I get an error when trying to compile complaining that the other namespace does not exist. Here's the error message:
"The type or namespace name 'IDrivers' could not be found (are you missing a using directive or an assembly reference?)"
I would apprecitate any help provided as I am new to C# and am completely stuck on this. Thanks
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No probs with the helping... we'll get this one cracked!!
If I can try to explain how I think you want to implement what I think your trying to do and you can scream at me and tell me I'm stupid 
* You have a forms app
* You have an assembly dll with interface definitions
* You have another assembly with an implementation of said interfaces.
You want to Have your app know about only the interfaces and dynamically at run time look into a dll assembly and instantiate a class which implements the interface...
This is how you do it...
* In a solution add the three projects.
* In your Main app in solution explorer you go to "references" and then right click and select "Add Reference". When the dialog comes up select the "Project References" tab and select the project which defines the interfaces.
* In the "plug-in" (the assembly which IMPLEMENTS the interface) do the same thing, Add Reference->Project References->Select the assembly which defines the interfaces.
To explain this bit. The compiler needs to know where these Dlls are for the linking stage so what happens when you add a project based reference is that Visual Studio will make sure an up-to-date copy of the appropriate assemblies are in your bin folder. If you use a non-project based reference you can get into trouble.
If you follow the above points, assuming your "usings" are correct too your app will build and assuming the path to the dynamically loading assembly is correct the whole thing will work. (Don't forget to test for a "FileNotFoundException")...
Hope that's a bit more help...
I __AM__ going to write an article about this issue!
Cheers
Shaun
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