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• Compilation problem in the standard x86_64 libraries

  - by user350282

  Hi everyone, I am having trouble compiling a program I have written. I have two different files with the same includes but only one generates the following error when compiled with g++ /usr/lib/gcc/x86_64-linux-gnu/4.4.1/../../../../lib/crt1.o: In function `_start': /build/buildd/eglibc-2.10.1/csu/../sysdeps/x86_64/elf/start.S:109: undefined reference to `main' collect2: ld returned 1 exit status The files I am including in my header are as follows: #include <google/sparse_hash_map> using google::sparse_hash_map; #include <ext/hash_map> #include <math.h> #include <iostream> #include <queue> #include <vector> #include <stack> using std::priority_queue; using std::stack; using std::vector; using __gnu_cxx::hash_map; using __gnu_cxx::hash; using namespace std; Searching the internet for those two lines hasn't resulted in anything to help me. I would be very grateful for any advice. Thank you

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• Get more error information from unhandled error

  - by Andrew Simpson

  I am using C# in a desktop application. I am calling a DLL written in C that I do not have the source code for. Whenever I call this DLL I get an untrapped error which I trap in an UnhandledException event/delegate. The error is : object reference not set to an instance of an object But the stack trace is empty. When I Googled this the info back was that the error was being hanlded eleswhere and then rethrown. But this can only be in the DLL I do not have the source code for. So, is there anyway I can get more info about this error? This is my code... in program.cs... AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException); static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e) { try { Exception _ex = (Exception)e.ExceptionObject; //the stact trace property is empty here.. } finally { Application.Exit(); } } My DLL... [DllImport("AutoSearchDevice.dll", EntryPoint = "Start", ExactSpelling = false, CallingConvention = CallingConvention.StdCall)] public static extern int Start(int ASD_HANDLE); An I call it like so: public static void AutoSearchStart() { try { Start(m_pASD); } catch (Exception ex) { } }

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• Need opinions on LaTeX and ever upgrading

  - by yCalleecharan

  Hi, I've been using LaTeX since 2005 with the TeXLive distribution and I've been upgrading as each new TeXLive distribution comes out. In the recent years I noticed an increase in new packages, updated packages and in one instance a new package bearing a different name replacing an old one by the same package author. A LaTeX document which relies heavily on packages and which has been produced a few years back may start to get some warnings and error messages on present-day LaTeX compilation. The primary reason I switched to LaTeX is because of its reliability and robustness to create big documents easily, not to mention the adorable typographic quality. With LaTeX one doesn't have to worry about how to open a docx in an old program supporting only doc for instance. Now, when there are so much continual changes in the packages in a LaTeX distribution, I tend to wonder when will this madness end. Not that having enhanced and new features are bad in packages, but not all updated packages are backward compatible. Eventually one would like to be able to compile a LaTeX file in 10 years time that he/she is working on at present and not get any compilation warnings/error messages due to some unpredictable behavior of updated packages or due to a package that has been cast-off from a LaTeX distribution. If I understand correctly CTAN do keep a database with all packages from different versions. I would like to know how you LaTeX users handle this issue. Thanks a lot...

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• Multiple grids in one area

  - by anon

  I'm currently creating a WPF application, using C# and XAML in Visual Studios 2010. I have a master grid. In that master grid I have a group bar which you can select different items. Depending on what you select, the middle of the master grid can be totally different. What I was wondering is, what's the best way to program the middle part? Right now, I have it set up in such a way that everything in the middle is dynamically programed in C#, and everything on the outside is programmed in XAML. In C# I programmed: for each group bar item, there is a grid that goes with it (so that different content can be displayed on it). Each grid is a child of the master grid. Each grid is visible or hidden when necessary. Is this the best way to approach this? The best example of this is in Outlook 2007, where you have your group bar on the right hand side. When you select different items on the group bar (mail, calendar, tasks) the right of the group bar completely changes.

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• Firefox proxy dilemma

  - by Mike L.

  Any idea why when using system proxy settings in firefox, it can not accept a proxy such as: user:[email protected]:port ??? IE will allow and connect to a proxy in this format. Not only does firefox not work, but it does not prompt for the password, nor attempt to make a connection to the proxy. Basically get a "proxy server not found" error. Anybody know a way around this? I am working on a proxy switching program for IE & Firefox, and I would like to use system-wide proxy settings. If I just store the server:port combination, firefox prompts for the password, as well as IE. Then they can be cached and it will not ask again. Maybe my only option is to programmatically cache the user/pass? Anybody know a way to do this? I am pretty sure IE stores them at HTTP basic authentication passwords and I can add them with AddCredential. After saving a password for a proxy in firefox, it shows up in saved passwords in a format like "moz-proxy://server:port" anybody know how to programmatically add a saved password to firefox? Thanks

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• Creating a new object destroys an older object with different name in C++

  - by Mikael

  First question here! So, I am having some problems with pointers in Visual C++ 2008. I'm writing a program which will control six cameras and do some processing on them so to clean things up I have created a Camera Manager class. This class handles all operations which will be carried out on all the cameras. Below this is a Camera class which interacts with each individual camera driver and does some basic image processing. Now, the idea is that when the manager is initialised it creates two cameras and adds them to a vector so that I can access them later. The catch here is that when I create the second camera (camera2) the first camera's destructor is called for some reason, which then disconnects the camera. Normally I'd assume that the problem is somewhere in the Camera class, but in this case everything works perfectly as long as I don't create the camera2 object. What's gone wrong? CameraManager.h: #include "stdafx.h" #include <vector> #include "Camera.h" class CameraManager{ std::vector<Camera> cameras; public: CameraManager(); ~CameraManager(); void CaptureAll(); void ShowAll(); }; CameraManager.cpp: #include "stdafx.h" #include "CameraManager.h" CameraManager::CameraManager() { printf("Camera Manager: Initializing\n"); [...] Camera *camera1 = new Camera(NodeInfo,1, -44,0,0); cameras.push_back(*camera1); // Adding the following two lines causes camera1's destructor to be called. Why? Camera *camera2 = new Camera(NodeInfo,0, 44,0,0); cameras.push_back(*camera2); printf("Camera Manager: Ready\n"); }

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• Create JTable in a JPanel and add row

  - by DK64

  On my program I've dinamically created a JFrame that contains a JPanel called jp. jp also contains a JTable that I would like to fill with some rows. case KeyEvent.VK_R: JFrame frame = new JFrame("Snake v2.0 - Rankings"); JPanel jp = new JPanel(); jp.setPreferredSize(new Dimension(300,300)); JTable table = new JTable(); JScrollPane tableContainer = new JScrollPane(table); jp.add(tableContainer, BorderLayout.CENTER); DefaultTableModel tm = (DefaultTableModel) table.getModel(); tm.addRow(new Object[] {"#","Player","Score","Date"}); frame.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE); frame.setLocationRelativeTo(null); frame.setResizable(false); frame.getContentPane().add(jp); frame.pack(); frame.setVisible(true); break; This is my code. When I press R on the keyboard, the JFrame with that JPanel inside appears but the table doesnt (picture). What could I do?

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• STL vector performance

  - by iAdam

  STL vector class stores a copy of the object using copy constructor each time I call push_back. Wouldn't it slow down the program? I can have a custom linkedlist kind of class which deals with pointers to objects. Though it would not have some benefits of STL but still should be faster. See this code below: #include <vector> #include <iostream> #include <cstring> using namespace std; class myclass { public: char* text; myclass(const char* val) { text = new char[10]; strcpy(text, val); } myclass(const myclass& v) { cout << "copy\n"; //copy data } }; int main() { vector<myclass> list; myclass m1("first"); myclass m2("second"); cout << "adding first..."; list.push_back(m1); cout << "adding second..."; list.push_back(m2); cout << "returning..."; myclass& ret1 = list.at(0); cout << ret1.text << endl; return 0; } its output comes out as: adding first...copy adding second...copy copy The output shows the copy constructor is called both times when adding and when retrieving the value even then. Does it have any effect on performance esp when we have larger objects?

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• Largest triangle from a set of points

  - by Faken

  I have a set of random points from which i want to find the largest triangle by area who's verticies are each on one of those points. So far I have figured out that the largest triangle's verticies will only lie on the outside points of the cloud of points (or the convex hull) so i have programmed a function to do just that (using Graham scan in nlogn time). However that's where I'm stuck. The only way I can figure out how to find the largest triangle from these points is to use brute force at n^3 time which is still acceptable in an average case as the convex hull algorithm usually kicks out the vast majority of points. However in a worst case scenario where points are on a circle, this method would fail miserably. Dose anyone know an algorithm to do this more efficiently? Note: I know that CGAL has this algorithm there but they do not go into any details on how its done. I don't want to use libraries, i want to learn this and program it myself (and also allow me to tweak it to exactly the way i want it to operate, just like the graham scan in which other implementations pick up collinear points that i don't want).

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• ASP.NET - Accessing copied content

  - by James Kolpack

  I have a class library project which contains some content files configured with the "Copy if newer" copy build action. This results in the files being copied to a folder under ...\bin\ for every project in the solution. In this same solution, I've got a ASP.NET web project (which is MVC, by the way). In the library I have a static constructor load the files into data structures accessible by the web project. Previously I've been including the content as an embedded resource. I now need to be able to replace them without recompiling. I want to access the data in three different contexts: Unit testing the library assembly Debugging the web application Hosting the site in IIS For unit testing, Environment.CurrentDirectory points to a path containing the copied content. When debugging however, it points to C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE. I've also looked at Assembly.GetExecutingAssembly().Location which points to C:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\c44f9da4\9238ccc\assembly\dl3\eb4c23b4\9bd39460_f7d4ca01\. What I need is to the physical location of the webroot \bin folder, but since I'm in a static constructor in the library project, I don't have access to a Request.PhysicalApplicationPath. Is there some other environment variable or structure where I can always find my "Copy if newer" files?

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• camera picturecallback intent not work

  - by Simon

  After I take the photo, the program automatically goes back like onBackPressed(). When I remove the putExtra, the intent runs. When I put startActivity() after takePicture(), it transfers null data.... I just want to put the image data to another activity to have other use. How can it be achieved? private PictureCallback picture = new PictureCallback(){ @Override public void onPictureTaken(byte[] data, Camera camera) { // TODO Auto-generated method stub Intent intent = new Intent(CameraFilming.this, PhotoPreview.class); intent.putExtra("imageByte", data); //Picture data transfer to next activity startActivity(intent); } }; //take photo by pressing button private class captureBtnListener implements View.OnClickListener{ @Override public void onClick(View v){ capture.setOnClickListener(null); CountDownTimer timer = new CountDownTimer(10000, 1000){ @Override public void onTick(long millisUntilFinished) { // TODO Auto-generated method stub countdown.setText(millisUntilFinished/1000+""); } @Override public void onFinish() { // TODO Auto-generated method stub countdown.setText("0"); camera.takePicture(null, null, picture); } }; timer.start(); } } public class PhotoPreview extends Activity{ private RelativeLayout layout; private ImageView overlay, texture, face1, face2; @Override public void onCreate (Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.photo_preview); layout = (RelativeLayout)findViewById(R.id.preview_layout); byte[] data = getIntent().getByteArrayExtra("imageByte"); if (data == null){ Log.d("PhotoPreview", "no image data"); finish(); } Bitmap rawPhotoBitmap = BitmapFactory.decodeByteArray(data, 0, data.length); ImageProcess imgProcess = new ImageProcess(this); Bitmap resizedFace = imgProcess.scaleAccordingWidth(imgProcess.cropImage(rawPhotoBitmap, 840, 125, 440, 560), 77); face1 = new ImageView(this); face1.setImageBitmap(resizedFace); Log.d("testing", "testing"); } }

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• FORTRAN: Invalid form for an assignment

  - by Sam Goodness

  I can't get this code to compile uding either the g77 minGW compiler or the g95 compiler. Does anyone know why? I get these errors with the g77: diff5z10.for: In subroutine `diffract': diff5z10.for:579: Tropo100 = 20.34 - .077 * Dist ^ Invalid form for assignment statement at (^) diff5z10.for:581: IF (Freq .GT. 1000) FreqAdj = 24.5 - 7200/(Freq+3000) ^ Invalid form for assignment statement at (^) and i get these errors when compiling with g95: In file diff5z10.for:574 CLUTTER = steep*CLUTTER 1 Error: Unclassifiable statement at (1) In file diff5z10.for:580 FreqAdj = 23.978 - 58026.76 / (Freq + 2320) 1 Error: Unclassifiable statement at (1) here is the code from this section of the program: (starting with line 362) Span = .28 - .144 * (Round - 1.2) Para = C / Span**2 IF (Ratio .GT. .4) Para = 6.25 * (C - 1) CLUTTER = Para * (RATIO - .4)**2 - C IF (CLUTTER .GT. 0.) CLUTTER = 0. CSlope = SQRT(freq)/350 steep = 1 + CSlope * (dist - Horizon) IF (steep .LT. 0) steep = 0 IF (steep .GT. 1) steep = 1 CLUTTER = steep*CLUTTER Tropo100 = 20.34 - .077 * Dist FreqAdj = 23.978 - 58026.76 / (Freq + 2320) IF (Freq .GT. 1000) FreqAdj = 24.5 - 7200/(Freq+3000) TropoFd = Tropo100 - FreqAdj FS_field = 106.9 - 20 * LOG10(Dist) Scatter = TropoFd - FS_field !loss ref to free space DiffL = Scatter - DLOSS Combine = 150/(20 - DiffL) - 5 IF (DiffL .LT. -10) Combine = 0 IF (DiffL .GT. 10) Combine = DiffL DLOSS = DLOSS + Combine RETURN END

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• Specifying character

  - by danutenshu

  So below I have a code in C++ that is supposed to invert the arguments in a vector, but not the sequence. I have listed my problems as sidenotes in the code below. The invert function is supposed to invert each argument, and then the main function just outputs the inverted words in same order For instance, program("one two three four")=ruof eerth owt eno #include <iostream> #include <string> using namespace std; int invert(string normal) { string inverted; for (int num=normal.size()-1; num>=0; num--) { inverted.append(normal[num]); //I don't know how to get each character //I need another command for append } return **inverted**; <---- } int main(int argc, char* argv[]) { string text; for (int a=1; a<argc; a++) { text.append(invert(argv[a])); //Can't run the invert function text.append(" "); } cout << text << endl; return 0; }

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• Inheritance and type parameters of Traversable

  - by Jesper

  I'm studying the source code of the Scala 2.8 collection classes. I have questions about the hierarchy of scala.collection.Traversable. Look at the following declarations: package scala.collection trait Traversable[+A] extends TraversableLike[A, Traversable[A]] with GenericTraversableTemplate[A, Traversable] trait TraversableLike[+A, +Repr] extends HasNewBuilder[A, Repr] with TraversableOnce[A] package scala.collection.generic trait HasNewBuilder[+A, +Repr] trait GenericTraversableTemplate[+A, +CC[X] <: Traversable[X]] extends HasNewBuilder[A, CC[A] @uncheckedVariance] Question: Why does Traversable extend GenericTraversableTemplate with type parameters [A, Traversable] - why not [A, Traversable[A]]? I tried some experimenting with a small program with the same structure and got a strange error message when I tried to change it to Traversable[A]: error: Traversable[A] takes no type parameters, expected: one I guess that the use of the @uncheckedVariance annotation in GenericTraversableTemplate also has to do with this? (That seems like a kind of potentially unsafe hack to force things to work...). Question: When you look at the hierarchy, you see that Traversable inherits HasNewBuilder twice (once via TraversableLike and once via GenericTraversableTemplate), but with slightly different type parameters. How does this work exactly? Why don't the different type parameters cause an error?

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• Have you dealt with space hardening?

  - by Tim Post

  I am very eager to study best practices when it comes to space hardening. For instance, I've read (though I can't find the article any longer) that some core parts of the Mars rovers did not use dynamic memory allocation, in fact it was forbidden. I've also read that old fashioned core memory may be preferable in space. I was looking at some of the projects associated with the Google Lunar Challenge and wondering what it would feel like to get code on the moon, or even just into space. I know that space hardened boards offer some sanity in such a harsh environment, however I'm wondering (as a C programmer) how I would need to adjust my thinking and code if I was writing something that would run in space? I think the next few years might show more growth in private space companies, I'd really like to at least be somewhat knowledgeable regarding best practices. Can anyone recommend some books, offer links to papers on the topic or (gasp) even a simulator that shows you what happens to a program if radiation, cold or heat bombards a board that sustained damage to its insulation? I think the goal is keeping humans inside of a space craft (as far as fixing or swapping stuff) and avoiding missions to fix things. Furthermore, if the board maintains some critical system, early warnings seem paramount.

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• What are the default return values for operator< and operator[] in C++ (Visual Studio 6)?

  - by DustOff

  I've inherited a large Visual Studio 6 C++ project that needs to be translated for VS2005. Some of the classes defined operator< and operator[], but don't specify return types in the declarations. VS6 allows this, but not VS2005. I am aware that the C standard specifies that the default return type for normal functions is int, and I assumed VS6 might have been following that, but would this apply to C++ operators as well? Or could VS6 figure out the return type on its own? For example, the code defines a custom string class like this: class String { char arr[16]; public: operator<(const String& other) { return something1 < something2; } operator[](int index) { return arr[index]; } }; Would VS6 have simply put the return types for both as int, or would it have been smart enough to figure out that operator[] should return a char and operator< should return a bool (and not convert both results to int all the time)? Of course I have to add return types to make this code VS2005 C++ compliant, but I want to make sure to specify the same type as before, as to not immediately change program behavior (we're going for compatibility at the moment; we'll standardize things later).

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• Simple binary File I/O problem with cstdio(c++)

  - by Atilla Filiz

  The c++ program below fails to read the file. I know using cstdio is not good practice but that what I am used to and it should work anyway. $ ls -l l.uyvy -rw-r--r-- 1 atilla atilla 614400 2010-04-24 18:11 l.uyvy $ ./a.out l.uyvy Read 0 bytes out of 614400, possibly wrong file code: #include<cstdio> int main(int argc, char* argv[]) { FILE *fp; if(argc<2) { printf("usage: %s <input>\n",argv[0]); return 1; } fp=fopen(argv[1],"rb"); if(!fp) { printf("erör, cannot open %s for reading\n",argv[1]); return -1; } int bytes_read=fread(imgdata,1,2*IMAGE_SIZE,fp); //2bytes per pixel fclose(fp); if(bytes_read < 2*IMAGE_SIZE) { printf("Read %d bytes out of %d, possibly wrong file\n", bytes_read, 2*IMAGE_SIZE); return -1; } return 0; }

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• algorithm to generate maximum number of character 'A' using keystrokes 'A', CTRL + 'A', CTRL + 'C' and CTRL + 'V'

  - by munda

  This is an interview question from google. I am not able to solve it by myself. Can somebody throw some light? The question goes like this. Write a program to print the sequence of keystrokes such that it generates the maximum number of character 'A's. You are allowed to use only 4 keys: 'A', CTRL + 'A', CTRL + 'C' and CTRL + 'V'. Only N keystrokes are allowed. All CTRL+ characters are considered as one keystroke, so CTRL+A is one keystroke. e.g.: A, ctrl+A, ctrl+C, ctrl+V generates two As in 4 keystrokes. Edit: CTRL + A is Select All CTRL + C is copy CTRL + V is paste I did some mathematics. For any N, using x numbers of A's , one CTRL+A, one CTRL+C and y CTRL+V, we can generate max ((N-1)/2)^2 numbers of A's. But for some N M, it is better to use as many ^A, ^C and ^V as it doubles the number of As. Edit 2: ^A, ^V and ^C will not overwrite on the existing selection but it will append the copied selection to selected one.

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• OpenCV. cvFnName() works, but cv::FunName() doesn't work

  - by Innuendo

  I'm using OpenCV to write a plugin for a simulator. I've made an OpenCV project (single - not a plugin) and it works fine. When I added OpenCV libs to the plugin project, I added all libs required. Visual Studio 2010 doesn't highlight any code line with red. All looks fine and compiles fine. But in execution, the program halts with a Runtime Error on any cv::function. For example: cv::imread, or cv::imwrite. But if I replace them with cvLoadImage() and cvSaveImage(), it works fine. Why does this happen? I don't want to rewrite the whole script in old-api-style (cvFnName). It means I should change all Mat objects to IplImages, and so on. UPDATE: // preparing template ifstream ifile(tmplfilename); if ( !FILE_LOADED && ifile ) { // loading template file Mat tmpl = cv::imread(tmplfilename, 1); // << here occurs error FILE_LOADED = true; } Mat src; Bmp2Mat(hDC, hBitmap, src); TargetDetector detector(src, tmpl); detector.detectTarget(); If I change to: if ( !FILE_LOADED && ifile ) { IplImage* tmpl = 0; tmpl = cvLoadImage(tmplfilename, 1); // no error occurs } And then no error occurs. Early it displayed some Runtime Error. Now, I wanted to copy exact message and it just crashes the application (simulator, what I am pluginning). It displays window error - to kill process or no. (I can't show exact message, because I'm using russian windows now)

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• Java sockets: multiple client threads on same port on same machine?

  - by espcorrupt

  I am new to Socket programming in Java and was trying to understand if the below code is not a wrong thing to do. My question is: Can I have multiple clients on each thread trying to connect to a server instance in the same program and expect the server to read and write data with isolation between clients" public class Client extends Thread { ... void run() { Socket socket = new Socket("localhost", 1234); doIO(socket); } } public class Server extends Thread { ... void run() { // serverSocket on "localhost", 1234 Socket clientSock = serverSocket.accept(); executor.execute(new ClientWorker(clientSock)); } } Now can I have multiple Client instances on different threads trying to connect on the same port of the current machine? For example, Server s = new Server("localhost", 1234); s.start(); Client[] c = new Client[10]; for (int i = 0; i < c.length; ++i) { c.start(); }

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• How do I trace SQL Server Failure Audit events?

  - by Tim Perry

  I recently took over management of a Windows 2003 server. The application log is being filled up with messages like these: Event Type: Failure Audit Event Source: MSSQLSERVER Event Category: (4) Event ID: 18456 Date: 3/5/2010 Time: 4:00:30 PM User: N/A Computer: FAIROAKS1 Description: Login failed for user 'administrator'. [CLIENT: <local machine>] Data: 0000: 18 48 00 00 0e 00 00 00 .H...... 0008: 0a 00 00 00 46 00 41 00 ....F.A. 0010: 49 00 52 00 4f 00 41 00 I.R.O.A. 0018: 4b 00 53 00 31 00 00 00 K.S.1... 0020: 07 00 00 00 6d 00 61 00 ....m.a. 0028: 73 00 74 00 65 00 72 00 s.t.e.r. 0030: 00 00 .. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. I'd like to figure out what program is causing these. Is there a way to trace and find out which process is causing these errors?

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• Does F# documentation have a way to search for functions by their types?

  - by Nathan Sanders

  Say I want to know if F# has a library function of type ('T -> bool) -> 'T list -> int ie, something that counts how many items of a list that a function returns true for. (or returns the index of the first item that returns true) I used to use the big list at the MSR site for F# before the documentation on MSDN was ready. I could just search the page for the above text because the types were listed. But now the MSDN documentation only lists types on the individual pages--the module page is a mush of descriptive text. Google kinda-sorta works, but it can't help with // compatible interfaces ('T -> bool) -> Seq<'T> -> int // argument-swaps Seq<'T> -> ('T -> bool) -> int // type-variable names ('a -> bool) -> Seq<'a> -> int // wrappers ('a -> bool) -> 'a list -> option<int> // uncurried versions ('T -> bool) * 'T list -> int // .NET generic syntax ('T -> bool) -> List<'T> -> int // methods List<'T> member : ('T -> bool) -> int Haskell has a standalone program for this called Hoogle. Does F# have an equivalent, like Fing or something?

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• Is memory allocation in linux non-blocking?

  - by Mark

  I am curious to know if the allocating memory using a default new operator is a non-blocking operation. e.g. struct Node { int a,b; }; ... Node foo = new Node(); If multiple threads tried to create a new Node and if one of them was suspended by the OS in the middle of allocation, would it block other threads from making progress? The reason why I ask is because I had a concurrent data structure that created new nodes. I then modified the algorithm to recycle the nodes. The throughput performance of the two algorithms was virtually identical on a 24 core machine. However, I then created an interference program that ran on all the system cores in order to create as much OS pre-emption as possible. The throughput performance of the algorithm that created new nodes decreased by a factor of 5 relative the the algorithm that recycled nodes. I'm curious to know why this would occur. Thanks. *Edit : pointing me to the code for the c++ memory allocator for linux would be helpful as well. I tried looking before posting this question, but had trouble finding it.

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• C++ Namespaces & templates question

  - by Kotti

  Hi! I have some functions that can be grouped together, but don't belong to some object / entity and therefore can't be treated as methods. So, basically in this situation I would create a new namespace and put the definitions in a header file, the implementation in cpp file. Also (if needed) I would create an anonymous namespace in that cpp file and put all additional functions that don't have to be exposed / included to my namespace's interface there. See the code below (probably not the best example and could be done better with another program architecture, but I just can't think of a better sample...) Sample code (header) namespace algorithm { void HandleCollision(Object* object1, Object* object2); } Sample code (cpp) #include "header" // Anonymous namespace that wraps // routines that are used inside 'algorithm' methods // but don't have to be exposed namespace { void RefractObject(Object* object1) { // Do something with that object // (...) } } namespace algorithm { void HandleCollision(Object* object1, Object* object2) { if (...) RefractObject(object1); } } So far so good. I guess this is a good way to manage my code, but I don't know what should I do if I have some template-based functions and want to do basically the same. If I'm using templates, I have to put all my code in the header file. Ok, but how should I conceal some implementation details then? Like, I want to hide RefractObject function from my interface, but I can't simply remove it's declaration (just because I have all my code in a header file)... The only approach I came up with was something like: Sample code (header) namespace algorithm { // Is still exposed as a part of interface! namespace impl { template <typename T> void RefractObject(T* object1) { // Do something with that object // (...) } } template <typename T, typename Y> void HandleCollision(T* object1, Y* object2) { impl::RefractObject(object1); // Another stuff } } Any ideas how to make this better in terms of code designing?

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• iPhone crashing when presenting modal view controller

  - by Michael Waterfall

  I'm trying to display a modal view straight after another view has been presented modally (the second is a loading view that appears). - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; // Show load LoadViewController *loader = [[LoadViewController alloc] init]; [self presentModalViewController: loader animated:NO]; [loader release]; } But when I do this I get a "Program received signal: "EXC_BAD_ACCESS"." error. The stack trace is: 0 0x30b43234 in -[UIWindowController transitionViewDidComplete:fromView:toView:] 1 0x3095828e in -[UITransitionView notifyDidCompleteTransition:] 2 0x3091af0d in -[UIViewAnimationState sendDelegateAnimationDidStop:finished:] 3 0x3091ad7c in -[UIViewAnimationState animationDidStop:finished:] 4 0x0051e331 in run_animation_callbacks 5 0x0051e109 in CA::timer_callback 6 0x302454a0 in CFRunLoopRunSpecific 7 0x30244628 in CFRunLoopRunInMode 8 0x32044c31 in GSEventRunModal 9 0x32044cf6 in GSEventRun 10 0x309021ee in UIApplicationMain 11 0x00002154 in main at main.m:14 Any ideas? I'm totally stumped! The loading view is empty so there's definitely nothing going on in there that's causing the error. Is it something to do with launching 2 views modally in the same event loop or something? Thanks, Mike Edit: Very strange... I have modified it slightly so that the loading view is shown after a tiny delay, and this works fine! So it appears to be something within the same event loop! - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; // Show load [self performSelector:@selector(doit) withObject:nil afterDelay:0.1]; } - (void)doit { [self presentModalViewController:loader animated:YES]; }

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