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  • Hard Disk Not Counting Reallocated Sectors

    - by MetaNova
    I have a drive that is reporting that the current pending sectors is "45". I have used badblocks to identify the sectors and I have been trying to write zeros to them with dd. From what I understand, when I attempt writing data directly to the bad sectors, it should trigger a reallocation, reducing current pending sectors by one and increasing the reallocated sector count. However, on this disk both Reallocated_Sector_Ct and Reallocated_Event_Count raw values are 0, and dd fails with I/O errors when I attempt to write zeros to the bad sectors. dd works fine, however, when I write to a good sector. # dd if=/dev/zero of=/dev/sdb bs=512 count=1 seek=217152 dd: error writing ‘/dev/sdb’: Input/output error Does this mean that my drive, in some way, has no spare sectors to be used for reallocation? Is my drive just in general a terrible person? (The drive isn't actually mine, I'm helping a friend out. They might have just gotten a cheap drive or something.) In case it is relevant, here is the output of smartctl -i : Model Family: Western Digital Caviar Green (AF) Device Model: WDC WD15EARS-00Z5B1 Serial Number: WD-WMAVU3027748 LU WWN Device Id: 5 0014ee 25998d213 Firmware Version: 80.00A80 User Capacity: 1,500,301,910,016 bytes [1.50 TB] Sector Size: 512 bytes logical/physical Device is: In smartctl database [for details use: -P show] ATA Version is: ATA8-ACS (minor revision not indicated) SATA Version is: SATA 2.6, 3.0 Gb/s Local Time is: Fri Oct 18 17:47:29 2013 CDT SMART support is: Available - device has SMART capability. SMART support is: Enabled UPDATE: I have run shred on the disk, which has caused Current_Pending_Sector to go to zero. However, Reallocated_Sector_Ct and Reallocated_Event_Count are still zero, and dd is now able to write data to the sectors it was previously unable to. This leads me with several other questions: Why aren't the reallocations being recored by the disk? I'm assuming the reallocation took place as I can now write data directly to the sector and couldn't before. Why did shred cause reallocation and not dd? Does the fact that shred writes random data instead of just zeros make a difference?

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  • Use old raid drive as boot device without data loss

    - by Gabriel
    There were two disks in sw-raid. There were /dev/md1 as swap, /dev/md2 as boot and a /dev/md3 with ext4. The sw-raid was disabled by stopping and removing mdadm and then zeroing the superblock on each /dev/mdX partition with: sudo mdadm --zero-superblock /dev/sda1 sudo mdadm --zero-superblock /dev/sda2 sudo mdadm --zero-superblock /dev/sda3 In the disk that is the first boot device, I don't know if it's relevant, the system type of each partition was set back from fd to 82 or 83 with fdisk, /etc/fstab was updated, changing /dev/mdX to /dev/sdaX, and grub was reinstalled on the boot partition (/dev/sda2) with grub-instal. But the system wont boot. What else should I do to use this disk as the boot device without reinstall or data loss? Current output of fdisk Device Boot Start End Blocks Id System /dev/sda1 2048 33556480 16777216+ 82 Linux swap / Solaris /dev/sda2 * 33558528 34607104 524288+ 83 Linux /dev/sda3 34609152 3907027120 1936208984+ 83 Linux With it doesn't boot I mean that it stops in the grub console (with the grub> symbol). A ls command says: (hd0) (hd0,msdos3) (hd0,msdos2) (hd0,msdos1) (hd1) (hd1,msdos1) It's weird because hd1 was formatted with ext4...

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  • Impersonation - Access is denied

    - by krisg
    I am having trouble using impersonation to delete a PerformanceCounterCategory from an MVC website. I have a static class and when the application starts it checks whether or not a PerformanceCounterCategory exists, and if it contains the correct counters. If not, it deletes the category and creates it again with the required counters. It works fine when running under the built in webserver Cassini, but when i try run it through IIS7 (Vista) i get the following error: Access is denied Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.ComponentModel.Win32Exception: Access is denied The code used is from an MS article, from memory... var username = "user"; var password = "password"; var domain = "tempuri.org"; WindowsImpersonationContext impersonationContext; // if impersonation fails - return if (!ImpersonateValidUser(username, password, domain, out impersonationContext)) { throw new AuthenticationException("Impersonation failed"); } PerformanceCounterCategory.Delete(PerfCategory); UndoImpersonation(impersonationContext); ... private static bool ImpersonateValidUser(string username, string password, string domain, out WindowsImpersonationContext impersonationContext) { const int LOGON32_LOGON_INTERACTIVE = 2; const int LOGON32_PROVIDER_DEFAULT = 0; WindowsIdentity tempWindowsIdentity; var token = IntPtr.Zero; var tokenDuplicate = IntPtr.Zero; if (RevertToSelf()) { if (LogonUserA(username, domain, password, LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, ref token) != 0) { if (DuplicateToken(token, 2, ref tokenDuplicate) != 0) { tempWindowsIdentity = new WindowsIdentity(tokenDuplicate); impersonationContext = tempWindowsIdentity.Impersonate(); if (impersonationContext != null) { CloseHandle(token); CloseHandle(tokenDuplicate); return true; } } } } if (token != IntPtr.Zero) CloseHandle(token); if (tokenDuplicate != IntPtr.Zero) CloseHandle(tokenDuplicate); impersonationContext = null; return false; } [DllImport("advapi32.dll")] public static extern int LogonUserA(String lpszUserName, String lpszDomain, String lpszPassword, int dwLogonType, int dwLogonProvider, ref IntPtr phToken); [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern int DuplicateToken(IntPtr hToken, int impersonationLevel, ref IntPtr hNewToken); [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern bool RevertToSelf(); [DllImport("kernel32.dll", CharSet = CharSet.Auto)] public static extern bool CloseHandle(IntPtr handle); The error is thrown when processing tries to execute the PerformanceCounterCategory.Delete command. Suggestions?

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  • impersonation and BackgroundWorker

    - by Lucian D
    Hello guys, I have a little bit of a problem when trying to use the BackgroundWorker class with impersonation. Following the answers from google, I got this code to impersonate public class MyImpersonation{ WindowsImpersonationContext impersonationContext; [DllImport("advapi32.dll")] public static extern int LogonUserA(String lpszUserName, String lpszDomain, String lpszPassword, int dwLogonType, int dwLogonProvider, ref IntPtr phToken); [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern int DuplicateToken(IntPtr hToken, int impersonationLevel, ref IntPtr hNewToken); [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern bool RevertToSelf(); [DllImport("kernel32.dll", CharSet = CharSet.Auto)] public static extern bool CloseHandle(IntPtr handle); public bool impersonateValidUser(String userName, String domain, String password) { WindowsIdentity tempWindowsIdentity; IntPtr token = IntPtr.Zero; IntPtr tokenDuplicate = IntPtr.Zero; if (RevertToSelf()) { if (LogonUserA(userName, domain, password, LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, ref token) != 0) { if (DuplicateToken(token, 2, ref tokenDuplicate) != 0) { tempWindowsIdentity = new WindowsIdentity(tokenDuplicate); impersonationContext = tempWindowsIdentity.Impersonate(); if (impersonationContext != null) { CloseHandle(token); CloseHandle(tokenDuplicate); return true; } } } } if (token != IntPtr.Zero) CloseHandle(token); if (tokenDuplicate != IntPtr.Zero) CloseHandle(tokenDuplicate); return false; } } It worked really well until I've used it with the BackgroundWorker class. In this case, I've added a impersonation in the the code that runs asynchronously. I have no errors, but the issue I'm having is that the impersonation does not work when it is used in the async method. In code this looks something like this: instantiate a BGWorker, and add an event handler to the DoWork event: _bgWorker = new BackgroundWorker(); _bgWorker.DoWork += new DoWorkEventHandler(_bgWorker_DoWork); in the above handler, a impersonation is made before running some code. private void _bgWorker_DoWork(object sender, DoWorkEventArgs e) { MyImpersonation myImpersonation = new MyImpersonation(); myImpersonation.impersonateValidUser(user, domain, pass) //run some code... myImpersonation.undoImpersonation(); } the code is launched with BGWorker.RunWorkerAsync(); As I said before, no error is thrown, only that the code acts as if I did't run any impersonation, that is with it's default credentials. Moreover, the impersonation method returns true, so the impersonation took place at a certain level, but probably not on the current thread. This must happen because the async code runs on another thread, so there must be something that needs to be added to the MyImpersonation class. But what?? :) Thanks in advance, Lucian

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  • cannot evaluate expression because a native frame is on top of the call stack and system.accessviolationexception

    - by Joseph
    I have this code using c#. public partial class MainForm : Form { private CvCapture VideoCapture; private IplImage frame; private IplImage imgMain; public MainForm() { InitializeComponent(); } private void btnVideo_Click(object sender, EventArgs e) { double vidWidth, vidHeight; try { VideoCapture = highgui.CvCreateCameraCapture(0); } catch (Exception except) { MessageBox.Show(except.Message); } if (btnVideo.Text.CompareTo("Start Video") == 0) { if (VideoCapture.ptr == IntPtr.Zero) { MessageBox.Show("badtrip ah!!!"); return; } btnVideo.Text = "Stop Video"; highgui.CvSetCaptureProperty(ref VideoCapture, highgui.CV_CAP_PROP_FRAME_WIDTH, 640); highgui.CvSetCaptureProperty(ref VideoCapture, highgui.CV_CAP_PROP_FRAME_HEIGHT, 480); highgui.CvQueryFrame(ref VideoCapture); vidWidth = highgui.cvGetCaptureProperty(VideoCapture, highgui.CV_CAP_PROP_FRAME_WIDTH); vidHeight = highgui.cvGetCaptureProperty(VideoCapture, highgui.CV_CAP_PROP_FRAME_HEIGHT); picBoxMain.Width = (int)vidWidth; picBoxMain.Height = (int)vidHeight; timerGrab.Enabled = true; timerGrab.Interval = 42; timerGrab.Start(); } else { btnVideo.Text = "Start Video"; timerGrab.Enabled = false; if (VideoCapture.ptr == IntPtr.Zero) { highgui.CvReleaseCapture(ref VideoCapture); VideoCapture.ptr = IntPtr.Zero; } } } private void timerGrab_Tick(object sender, EventArgs e) { try { frame = highgui.CvQueryFrame(ref VideoCapture); if (frame.ptr == IntPtr.Zero) { timerGrab.Stop(); MessageBox.Show("??"); return; } imgMain = cxcore.CvCreateImage(cxcore.CvGetSize(ref frame), 8, 3); picBoxMain.Image = highgui.ToBitmap(imgMain, false); cxcore.CvReleaseImage(ref imgMain); //cxcore.CvReleaseImage(ref frame); } catch (Exception excpt) { MessageBox.Show(excpt.Message); } } } The problem is after i break all and step through the debugger the program stops at a certain code. the code where it stops is here: frame = highgui.CvQueryFrame(ref VideoCapture); the error is that it says that cannot evaluate expression because a native frame is on top of the call stack. and then when i try to shift+F11 it. there is another error saying that system.accessviolationexception. the stack trace says that: at System.Runtime.InteropServices.Marshal.CopyToManaged(IntPtr source, Object destination, Int32 startIndex, Int32 length) at CxCore.IplImage.get_ImageDataDb()

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  • Winsock Connect Problem with Eset Nod32

    - by AFgone
    Dear All, my socket library which is implemented using winsock2 is working properly. But when ESET Nod32 installed on the computer, connect() function returns 0(zero) ,that is success, even if remote host is not available. I looked with netstat -b command and saw that ekrn.exe is accepting the client. And after couple of seconds it sends zero byte of information,which means graceful close. So how can I overcome this problem? Many thanks, regards...

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  • How do I avoid the loader lock?

    - by Mark0978
    We have a managed app, that uses an assembly. That assembly uses some unmanaged C++ code. The Managed C++ code is in a dll, that depends on several other dlls. All of those Dlls are loaded by this code. (We load all the dll's that ImageCore.dll depends on first, so we can tell which ones are missing, otherwise it would just show up as ImageCore.dll failed to load, and the log file would give no clues as to why). class Interop { private const int DONT_RESOLVE_DLL_REFERENCES = 1; private static log4net.ILog log = log4net.LogManager.GetLogger("Imagecore.NET"); [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr LoadLibraryEx(string fileName, IntPtr dummy, int flags); [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr FreeLibrary(IntPtr hModule); static private String[] libs = { "log4cplus.dll", "yaz.dll", "zlib1.dll", "libxml2.dll" }; public static void PreloadAssemblies() { for (int i=0; i < libs.Length; ++i) { String libname = libs[i]; IntPtr hModule = LoadLibraryEx(libname, IntPtr.Zero, DONT_RESOLVE_DLL_REFERENCES); if(hModule == IntPtr.Zero) { log.Error("Unable to pre-load '" + libname + "'"); throw new DllNotFoundException("Unable to pre-load '" + libname + "'"); } else { FreeLibrary(hModule); } } IntPtr h = LoadLibraryEx("ImageCore.dll", IntPtr.Zero, 0); if (h == IntPtr.Zero) { throw new DllNotFoundException("Unable to pre-load ImageCore.dll"); } } } And this code is called by public class ImageDoc : IDisposable { static ImageDoc() { ImageHawk.ImageCore.Utility.Interop.PreloadAssemblies(); } ... } Which is static constructor. As near as I can understand it, as soon as we attempt to use an ImageDoc object, the dll that contains that assembly is loaded and as part of that load, the static constructor is called which in turn causes several other DLLs to be loaded as well. What I'm trying to figure out, is how do we defer loading of those DLLs so that we don't run smack dab into this loader lock that is being kicked out because of the static constructor. I've pieced this much together by looking at: http://social.msdn.microsoft.com/Forums/en-US/vsto/thread/dd192d7e-ce92-49ce-beef-3816c88e5a86 http://msdn.microsoft.com/en-us/library/aa290048%28VS.71%29.aspx http://forums.devx.com/showthread.php?t=53529 http://www.yoda.arachsys.com/csharp/beforefieldinit.html But I just can't seem to find a way to get these external DLLs to load without it happening at the point the class is loading. I think I need to get these LoadLibrary calls out of the static constructor, but don't know how to get them called before they are needed (except for how it is done here). I would prefer to not have to put this kind of knowledge of the dlls into every app that uses this assembly. (And I'm not sure that would even fix the problem.... The strange thing is that the exception only appears to be happening while running within the debugger, not while running outside the debugger.

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  • Speed boost to adjacency matrix

    - by samoz
    I currently have an algorithm that operates on an adjacency matrix of size n by m. In my algorithm, I need to zero out entire rows or columns at a time. My implementation is currently O(m) or O(n) depending on if it's a column or row. Is there any way to zero out a column or row in O(1) time?

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  • velocity vector

    - by wanderer
    Hi, I am trying to simulate a collision. The collision is shown here http://www.freeimagehosting.net/image.php?c5ae01b476.jpg A particle falls down on a sphere and a collision between sphere and particle takes place. The sphere always remain stationary and the collision itself is not elastic. So if the particle falls directly n top of sphere, the velocity of particle will become zero. I was trying to set the velocity of particle to be zero after the collision. But that does not give good simulation when the collision does not occur on top of sphere but along the side of sphere. So now after the collision i need to make sure that the particle has a velocity which is orthogonal to the vector of the point of collision from the center of sphere. The velocity along the vector from center of sphere to point of collision should become zero. How do i do that? I am a bit mathematically challenged but i think it has something to do with dot product of vectors. Or maybe i am wrong :) I have the initial velocity vector and 'radiusvector' say :- 1)velocity <-1.03054, -1.56563, 1.33341e-016 2) radius vector <2.04406, 2.19587, 1.0514 Pseudo code for the problem is: foreach( particle particle in particlesCollections) { //sphere.x, sphere.y sphere.z give the center of the sphere dist = particle.pos-vector(sphere.x,sphere.y,sphere.z); //detect if a collision has taken place. if (dist.mag < sphere.radius) { rVector=dist/dist.mag*sphere.radius; particle.pos=vector(sphere.x,sphere.y,sphere.z) + rVector; //particle.Velocity gives the velocity vector of the particle at the time of collision //i need to modify particle.Velocity so that the component of velocity that runs along // with the rvector becomes zero as i have a non elsatic collision. The remaining //velocity that the particle will have is the one which runs along with tangent to the //rVector. The sphere remains stationary. //example values: particle.Velocity == <-1.03054, -1.56563, .006> //and rVector = <2.04406, 2.19587, 1.0514> } } Thanks

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  • How do I make a module in PLT Scheme?

    - by kunjaan
    I tried doing this: #lang scheme (module duck scheme/base (provide num-eggs quack) (define num-eggs 2) (define (quack n) (unless (zero? n) (printf "quack\n") (quack (sub1 n))))) But I get this error: module: illegal use (not at top-level) in: (module duck scheme/base (provide num-eggs quack) (define num-eggs 2) (define (quack n) (unless (zero? n) (printf "quack\n") (quack (sub1 n))))) what is the correct way?

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  • SSRS stop report generation on 0 records

    - by AmiT
    Hi All, I am creating a report from ssrs, and storing at local shared folder(MyReports) in excel format using data-driven subscription. It generates a report on scheduled time. But, I don't wanna create a report with zero records. How to stop SSRS to generate a report if no. of records is zero. Pls F1 me ... !

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  • c# uploading file - error

    - by user228058
    I have a webpage where the user can upload an excel file. I'm trying 2 different files - one works without a problem, and the other one gives me this error: Error: Length cannot be less than zero. Parameter name: length I know that sometimes this occurs when the file size is zero, but that is not the case here. Can anyon shed light on this issue? Please let me know if you need more info.

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  • Unmanaged Code calling leads to heavy memory leak!!

    - by konnychen
    Maybe I need change the title as "Unmanaged Code calling leads to heavy memory leak!" The leak is around 30M/hour I think maybe I need complete my code here because the memory leak maybe not from a static string whereas my real code derive this string from external device (see new code attached). so I handle also unmanaged code. Could it be possible the leak comes from unmanaged code? But I freed the resouce by Marshal.FreeCoTaskMem(pos); oThread2 = new Thread(new ThreadStart(Cyclic_Call)); oThread2.Start(); delegate void SetText_lab_Statubar(string text); private void m_SetText_lab_Statubar(string text) { if (this.lab_Statubar.InvokeRequired) { SetText_lab_Statubar d = new SetText_lab_Statubar(m_SetText_lab_Statubar); this.Invoke(d, new object[] { text }); } else { this.lab_Statubar.Text = text; } } private void Cyclic_Call() { do { //... ... ReadMatrixCode(Station6, 0, str_Code); this.m_SetText_lab_Statubar(str_Code[4]); Thread.Sleep(100); } while (!b_AbortThraed); } private void ReadMatrixCode(Station st, int ItemNr, string[] str_Code) { IntPtr pItemStates = IntPtr.Zero; IntPtr pErrors = IntPtr.Zero; int NumItems = itemServerHandles.Length; m_SyncIO.Read(DataSrc, NumItems, itemServerHandles, out pItemStates, out pErrors); // This calls external dll which has some of "out IntPtr" errors = new int[NumItems]; Marshal.Copy(pErrors, errors, 0, NumItems); IntPtr pos = pItemStates; // Now get the read values and check errors for (int dwCount = 0; dwCount < NumItems; dwCount++) { result[dwCount] = (ITEMSTATE)Marshal.PtrToStructure(pos, typeof(ITEMSTATE)); pos = (IntPtr)(pos.ToInt32() + Marshal.SizeOf(typeof(ITEMSTATE))); } // Free allocated COM-ressouces Marshal.FreeCoTaskMem(pItemStates); Marshal.FreeCoTaskMem(pErrors); pItemStates = IntPtr.Zero; pErrors = IntPtr.Zero; } m_syncIO is a class and finally it will call COM component which is defined below [Guid("39C12B52-011E-11D0-9675-1020AFD8ADB3")] [InterfaceType(1)] [ComConversionLoss] public interface ISyncIO { void Read(DATASOURCE dwSource, int dwCount, int[] phServer, out IntPtr ppItemValues, out IntPtr ppErrors); void Write(int dwCount, int[] phServer, object[] pItemValues, out IntPtr ppErrors); }

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  • Why does C# exit when calling the Ada elaboration routine using debug?

    - by erict
    I have a DLL created in Ada using GPS. I am dynamically loading it and calling it successfully both from Ada and from C++. But when I try to call it from C#, the program exits on the call to Elaboration init. What am I missing? The exact same DLL is perfectly happy getting called from C++ and Ada. Edit: If I start the program without Debugging, it also works with C#. But if I run it with the Debugger, then it exits on the call to ElaborationInit. There are no indications in any of the Windows event logs. If the Ada DLL is Pure, and I skip the elaboration init call, the actual function DLL is called correctly, so it has something to do with the elaboration. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; namespace CallingDLLfromCS { class Program { [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern IntPtr LoadLibrary(string dllToLoad); [DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true)] public static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName); [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern bool FreeLibrary(IntPtr hModule); [UnmanagedFunctionPointer(CallingConvention.StdCall)] delegate int AdaCallable2_dlgt(int val); static AdaCallable2_dlgt fnAdaCallable2 = null; [UnmanagedFunctionPointer(CallingConvention.StdCall)] delegate void ElaborationInit_dlgt(); static ElaborationInit_dlgt ElaborationInit = null; [UnmanagedFunctionPointer(CallingConvention.StdCall)] delegate void AdaFinal_dlgt(); static AdaFinal_dlgt AdaFinal = null; static void Main(string[] args) { int result; bool fail = false; // assume the best IntPtr pDll2 = LoadLibrary("libDllBuiltFromAda.dll"); if (pDll2 != IntPtr.Zero) { // Note the @4 is because 4 bytes are passed. This can be further reduced by the use of a DEF file in the DLL generation. IntPtr pAddressOfFunctionToCall = GetProcAddress(pDll2, "AdaCallable@4"); if (pAddressOfFunctionToCall != IntPtr.Zero) { fnAdaCallable2 = (AdaCallable2_dlgt)Marshal.GetDelegateForFunctionPointer(pAddressOfFunctionToCall, typeof(AdaCallable2_dlgt)); } else fail = true; pAddressOfFunctionToCall = GetProcAddress(pDll2, "DllBuiltFromAdainit"); if (pAddressOfFunctionToCall != IntPtr.Zero) { ElaborationInit = (ElaborationInit_dlgt)Marshal.GetDelegateForFunctionPointer(pAddressOfFunctionToCall, typeof(ElaborationInit_dlgt)); } else fail = true; pAddressOfFunctionToCall = GetProcAddress(pDll2, "DllBuiltFromAdafinal"); if (pAddressOfFunctionToCall != IntPtr.Zero) AdaFinal = (AdaFinal_dlgt)Marshal.GetDelegateForFunctionPointer(pAddressOfFunctionToCall, typeof(AdaFinal_dlgt)); else fail = true; if (!fail) { ElaborationInit.Invoke(); // ^^^^^^^^^^^^^^^^^^^^^^^^^ FAILS HERE result = fnAdaCallable2(50); Console.WriteLine("Return value is " + result.ToString()); AdaFinal(); } FreeLibrary(pDll2); } } } }

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  • C++0x Overload on reference, versus sole pass-by-value + std::move?

    - by dean
    It seems the main advice concerning C++0x's rvalues is to add move constructors and move operators to your classes, until compilers default-implement them. But waiting is a losing strategy if you use VC10, because automatic generation probably won't be here until VC10 SP1, or in worst case, VC11. Likely, the wait for this will be measured in years. Here lies my problem. Writing all this duplicate code is not fun. And it's unpleasant to look at. But this is a burden well received, for those classes deemed slow. Not so for the hundreds, if not thousands, of smaller classes. ::sighs:: C++0x was supposed to let me write less code, not more! And then I had a thought. Shared by many, I would guess. Why not just pass everything by value? Won't std::move + copy elision make this nearly optimal? Example 1 - Typical Pre-0x constructor OurClass::OurClass(const SomeClass& obj) : obj(obj) {} SomeClass o; OurClass(o); // single copy OurClass(std::move(o)); // single copy OurClass(SomeClass()); // single copy Cons: A wasted copy for rvalues. Example 2 - Recommended C++0x? OurClass::OurClass(const SomeClass& obj) : obj(obj) {} OurClass::OurClass(SomeClass&& obj) : obj(std::move(obj)) {} SomeClass o; OurClass(o); // single copy OurClass(std::move(o)); // zero copies, one move OurClass(SomeClass()); // zero copies, one move Pros: Presumably the fastest. Cons: Lots of code! Example 3 - Pass-by-value + std::move OurClass::OurClass(SomeClass obj) : obj(std::move(obj)) {} SomeClass o; OurClass(o); // single copy, one move OurClass(std::move(o)); // zero copies, two moves OurClass(SomeClass()); // zero copies, one move Pros: No additional code. Cons: A wasted move in cases 1 & 2. Performance will suffer greatly if SomeClass has no move constructor. What do you think? Is this correct? Is the incurred move a generally acceptable loss when compared to the benefit of code reduction?

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  • Django: FloatField or DecimalFied for Currency ?

    - by Hellnar
    I am curious which one would be better fitting as a currency field ? I will do simple operations such as taking difference, the percentage between old and new prices. I plan to keep two digits after the zero (ie 10.50) and majority of the time if these digits are zero, I will be hiding these numbers and display it as "10"

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  • Java configuration framework

    - by Steen
    I'm in the process of weeding out all hardcoded values in a java library and was wondering what framework would be the best (in terms of zero- or close-to-zero configuration) to handle run-time configuration? I would prefer xml-based config-files, but it's not essential. Please do only reply if you have practical experience with a framework. I'm not looking for examples, but experience... Thanks for taking the time.

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  • .NET read binary contents of .lnk file

    - by Flores
    I want to read the binary contents of a .lnk file. As long as the target of the shortcut (lnk file) exists this works fine with IO.File.ReadAllBytes(string file). BUT If the target of the shortcut does not exist (believe me I want this) the method only returns zero's. I guess this is because the OS follows the link and if it does not exist it returns zero's Is there some way to bypass the fact that the framework follows the target of the .lnk before displaying the contents of the .lnk file?

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  • Is it guaranteed that False == 0 and True == 1 in Python?

    - by EOL
    Is it guaranteed that False == 0 and True == 1, in Python? For instance, is it in any way guaranteed that the following code will always produce the same results, whatever the version of Python (existing and in the foreseeable future)? 0 == False # True 1 == True # True ['zero', 'one'][False] # is 'zero' Any reference to the official documentation would be much appreciated! Other comments would be appreciated too… :)

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  • DeviceIoControl returning false

    - by Anand
    In my C# code,DeviceIoControl is returning false,the handle is correct DeviceIoControl(deviceHandle, IOCTL_STORAGE_GET_DEVICE_NUMBER, IntPtr.Zero, 0, OutBuffPtr,//&psdn, OutBuffSize, ref dwBytesReturned, IntPtr.Zero);

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  • Why is the Objective-C Boolean data type defined as a signed char?

    - by EddieCatflap
    Something that has piqued my interest is Objective-C's BOOL type definition. Why is it defined as a signed char (which could cause unexpected behaviour if a value greater than 1 byte in length is assigned to it) rather than as an int, as C does (much less margin for error: a zero value is false, a non-zero value is true)? The only reason I can think of is the Objective-C designers micro-optimising storage because the char will use less memory than the int. Please can someone enlighten me?

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  • Collision Detection probelm (intersection with plane)

    - by Demi
    I'm doing a scene using openGL (a house). I want to do some collision detection, mainly with the walls in the house. I have tried the following code: // a plane is represented with a normal and a position in space Vector planeNor(0,0,1); Vector position(0,0,-10); Plane p(planeNor,position); Vector vel(0,0,-1); double lamda; // this is the intersection point Vector pNormal; // the normal of the intersection // this method is from Nehe's Lesson 30 coll= p.TestIntersionPlane(vel,Z,lamda,pNormal); glPushMatrix(); glBegin(GL_QUADS); if(coll) glColor3f(1,0,0); else glColor3f(1,1,1); glVertex3d(0,0,-10); glVertex3d(3,0,-10); glVertex3d(3,3,-10); glVertex3d(0,3,-10); glEnd(); glPopMatrix(); Nehe's method: #define EPSILON 1.0e-8 #define ZERO EPSILON bool Plane::TestIntersionPlane(const Vector3 & position,const Vector3 & direction, double& lamda, Vector3 & pNormal) { double DotProduct=direction.scalarProduct(normal); // Dot Product Between Plane Normal And Ray Direction double l2; // Determine If Ray Parallel To Plane if ((DotProduct<ZERO)&&(DotProduct>-ZERO)) return false; l2=(normal.scalarProduct(position))/DotProduct; // Find Distance To Collision Point if (l2<-ZERO) // Test If Collision Behind Start return false; pNormal= normal; lamda=l2; return true; } Z is initially (0,0,0) and every time I move the camera towards the plane, I reduce its z component by 0.1 (i.e. Z.z-=0.1 ). I know that the problem is with the vel vector, but I can't figure out what the right value should be. Can anyone please help me?

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