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• How to improve performance

  - by Ram

  Hi, In one of mine applications I am dealing with graphics objects. I am using open source GPC library to clip/merge two shapes. To improve accuracy I am sampling (adding multiple points between two edges) existing shapes. But before displaying back the merged shape I need to remove all the points between two edges. But I am not able to find an efficient algorithm that will remove all points between two edges which has same slope with minimum CPU utilization. Currently all points are of type PointF Any pointer on this will be a great help.

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• FORTRAN function returning an array causes a segfault (calling from C++)

  - by Dane Larsen

  Basically, here's my problem. I'm calling someone else's FORTRAN functions from my C++ code, and it's giving me headaches. Some code: function c_error_message() character(len = 255) :: c_error_message errmsg(1:9) = 'ERROR MSG' return end That's the FORTRAN function. My first question is: Is there anything in there that would cause a segfault? If not, then second: What does that return? A pointer? I'm trying to call it with the following C statement: char *e = c_error_message_(); That causes a segfault. c_error_message(); That too causes a segfault. I declared c_error_message_() earlier on with the following code: extern"C" { char* c_error_message_(); } Would declaring a function with a different return type than the actual return type cause a segfault? I'm at a loss. Thanks for any replies.

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• how to draw a line between two labels in a panel where labels are added during runtime

  - by vybhav

  A panel contains two labels which are generated by mouse clicks on the panel. I want to connect these two labels by drawing a line between them probably by dragging the mouse pointer from one label to another. There are two events here - one is clicking on the panel to generate the labels and the second is connecting these two labels (mouse pressed, mouse dragged and mouse released events). Both these event need to call the repaint() method but for different purposes. But there can be only one paint() method. The problem is when I connect these two labels, the line comes up but the rest of the components on the panel disappear.

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• Unable to create unmanaged object using new keyword in managed C++

  - by chair79

  Hi all, I've created a class with a boost::unordered_map as a member, Linkage.h #ifndef LINKAGE_H #define LINKAGE_H #include <boost/unordered_map.hpp> class Linkage { private: boost::unordered_map<int, int> m_IOMap; public: .... }; Linkage.cpp #include "stdafx.h" ... // methods and in the managed side of C++, I try to create the pointer of the obj: private: System::Void Form1_Load(System::Object^ sender, System::EventArgs^ e) { Linkage* m_pLink = new Linkage(); ..... } However this produces errors: Error 4 error LNK2005: "private: static unsigned int const boost::detail::type_with_alignment_imp<4>::found" (?found@?$type_with_alignment_imp@$03@detail@boost@@$$Q0IB) already defined in Proj_Test.obj Linkage.obj ..... Error 7 fatal error LNK1169: one or more multiply defined symbols found Could anyone explain to me pls? Thanks.

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• addObjectsFromArray

  - by derek.lo

  I have a question about memory management when using the addObjectsFromArray method. Basically, I have 2 arrays defined in the appDelegate. I need these 2 arrays for the duration of my application's runtime. I therefore release them in my appDelegate's dealloc method. When I go to use these two arrays in a class, I want one array to store the values from the other, so that the other can have it's contents removed, but still stick around for use. Something like this: [appDelegate.arrayTwo addObjectsFromArray:appDelegate.arrayOne]; [appDelegate.arrayOne removeAllObjects]; I'm getting the compiler error: EXC_BAD_ACCESS because of a pointer issue? retaining issue? Any help would be greatly appreciated! Thanks

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• HierarchicalDataTemplate Link By Parent

  - by Andrew Kalashnikov

  Hello colleagues. I want bind my treeview. There are a lot of samples binding treeview by object, which contains children collection. I've got domain having just Parent pointer. public class Service : BaseDomain { public virtual string Name { get; set; } public virtual string Description { get; set; } public virtual Service Parent { get; set; } } Can I bind collection of this objects to my treeView. Thanks

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• Are there any Python reference counting/garbage collection gotchas when dealing with C code?

  - by Jason Baker

  Just for the sheer heck of it, I've decided to create a Scheme binding to libpython so you can embed Python in Scheme programs. I'm already able to call into Python's C API, but I haven't really thought about memory management. The way mzscheme's FFI works is that I can call a function, and if that function returns a pointer to a PyObject, then I can have it automatically increment the reference count. Then, I can register a finalizer that will decrement the reference count when the Scheme object gets garbage collected. I've looked at the documentation for reference counting, and don't see any problems with this at first glance (although it may be sub-optimal in some cases). Are there any gotchas I'm missing? Also, I'm having trouble making heads or tails of the cyclic garbage collector documentation. What things will I need to bear in mind here? In particular, how do I make Python aware that I have a reference to something so it doesn't collect it while I'm still using it?

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• C++ - Opening a file inside a function using fopen. (Noob problem)

  - by Josh

  I am using Visual Studio 2005 (C++). I am passing a string into a function as a char array. I want to open the file passed in as a parameter and use it. I know my code works to an extent, because if I hardcode the filename as the first parameter it works perfectly. I do notice if I look at the value as a watch, the value includes the address aside the string literal. I have tried passing in the filename as a pointer, but it then complains about type conversion with __w64. As I said before it works fine with "filename.txt" in place of fileName. I am stumped. void read(char fileName[50],int destArray[MAX_R][MAX_C],int demSize[2]) { int rows=0; int cols=0; int row=0; int col=0; FILE * f = fopen(fileName,"r"); ...

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• Process for linking static ObjC libraries in XCode

  - by madmik3

  I'm trying to link to a static library and I keep getting linker errors. I've found a few sites that post examples but I have not been able to see what I am doing wrong. First I create a project that will link to my lib add existing files find my .xcodeproj file select "Copy items into destination groups folder"... Select my host project as Add To Targets. Then I add a direct dependency to my host app expand targets double click MyHost.app click + under direct dependencies select my lib Then I set build flags double click MyHost application icon in Groups and Files. click the build tab then I set the OtherLinerFlag to -ObjC then I set Header Search Paths to my header file location for my static library. I pass the compile stage but any classes in my static lib cause linker error: literal-pointer@_OBJC@_cls_refs@SomeClass in MyHost.o thanks!

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• got a question about Linked-List in java code.

  - by glacier89

  Linked-List: Mirror Consider the following private class for a node of a singly-linked list of integers: private class Node{ public int value; public Node next; } A wrapper-class, called, ListImpl, contains a pointer, called start to the first node of a linked list of Node. Write an instance-method for ListImpl with the signature: public void mirror(); That makes a reversed copy of the linked-list pointed to by start and appends that copy to the end of the list. So, for example the list: start 1 2 3 after a call to mirror, becomes: start 1 2 3 3 2 1 Note: in your answer you do not need to dene the rest of the class for ListImpl just the mirror method.

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• C# SendMessage to C++ WinProc

  - by jws

  I need to send a string from C# to a C++ WindowProc. There are a number of related questions on SO related to this, but none of the answers have worked for me. Here's the situation: PInvoke: [DllImport("user32", CharSet = CharSet.Auto)] public extern static int SendMessage(IntPtr hWnd, uint wMsg, IntPtr wParam, string lParam); C#: string lparam = "abc"; NativeMethods.User32.SendMessage(handle, ConnectMsg, IntPtr.Zero, lparam); C++: API LRESULT CALLBACK HookProc (int code, WPARAM wParam, LPARAM lParam) { if (code >= 0) { CWPSTRUCT* cwp = (CWPSTRUCT*)lParam; ... (LPWSTR)cwp->lParam <-- BadPtr ... } return ::CallNextHookEx(0, code, wParam, lParam); } I've tried a number of different things, Marshalling the string as LPStr, LPWStr, also tried creating an IntPtr from unmanaged memory, and writing to it with Marshal.WriteByte. The pointer is the correct memory location on the C++ side, but the data isn't there. What am I missing?

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• Gruber URL Regex tweak to capture "domain.com"

  - by mootymoots

  I found an updated version of John Gruber's regex for url matching in this post by user GianPac, which states it's been adapted to recognize url without protocol or the www part: (?i)\b((?:[a-z][\w-]+:(?:/{1,3}|[a-z0-9%])|www\d{0,3}[.]|[a-z0-9.-]+[.][a-z]{2,4}/?)(?:[^\s()<]+|(([^\s()<]+|(([^\s()<]+)))))(?:(([^\s()<]+|(([^\s()<]+))))|[^\s`!()[]{};:'\".,<?«»“”‘’])) Whilst this works in most cases, I found it does not match "google.com". It does match "google.comm" and "google.co.uk", so this must be a small oversight. The trouble is, I literally hate regex. It's the bane of my life. I just want to try and tweak this one more time to allow for "google.com" - can anyone throw me a pointer? I (think) it's something to do with this part of the code: +[.][a-z]{2,4}/?) ?

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• How to unmangle exported symbols from C++ in dynamic libraries in XCode on OSX

  - by Gerald

  I've been trying to develop a dynamic library in C++ that can be run-time loaded in an application. I finally got it working, but it's a little ugly. I have a function that takes a pointer to a C++ class as an argument, which looks like this: bool registerGrindPlugin( Grind::PluginManager* mgr ); But of course it's being exported as: _Z19registerGrindPluginPN5Grind13PluginManagerE I tried a .c file with a simple function and it exported fine as "registerGrindPlugin", but of course I can't pass a C++ class as the argument that way. Soo... my question is, is there a way to unmangle or alias the exported symbol so that I don't have to use a monstrosity like Z19registerGrindPluginPN5Grind13PluginManagerE in my dlsym call? I did see something about -alias_list as a linker option, but I haven't quite figured out how to use it in XCode. If that is the solution, can somebody provide some more details on how to use this?

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• Are there any C++ tools that detect misuse of static_cast, dynamic_cast, and reinterpret_cast?

  - by chrisp451

  The answers to the following question describe the recommended usage of static_cast, dynamic_cast, and reinterpret_cast in C++: http://stackoverflow.com/questions/332030/when-should-static-cast-dynamic-cast-and-reinterpret-cast-be-used Do you know of any tools that can be used to detect misuse of these kinds of cast? Would a static analysis tool like PC-Lint or Coverity Static Analysis do this? The particular case that prompted this question was the inappropriate use of static_cast to downcast a pointer, which the compiler does not warn about. I'd like to detect this case using a tool, and not assume that developers will never make this mistake.

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• Eclipse - CDT Content Assist extremely slow

  - by Salil

  Hi.. I just installed eclipse-cdt 3.2.2 on Linux (Mint). The content assist feature which pops up when you do a "." or "-" on a struct or struct pointer, is extremely slow and freezes the entire IDE for around 10-20 seconds. This I feel, is because it searches through the entire include directory /usr/include that comes by default for any C project that you create. How can this issue be solved? Thanks..

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• Jquery clickable block

  - by Clint

  HI, I have this code for extracting the href and adding it to a parent block... $(".new-dev").hover(function(){ $(this).css('cursor','pointer'); $('this').$('a').css('color','#696969'); },function(){ $('this').$('a').css('color','#000'); }); What I want to do is make the a within the block change color on rollover. Unsure of how to do this when using $(this). Any advice welcome. Thanks, C

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• How can I create a collection of references in C#

  - by Jonathan Kaufman

  Ok I am having a cross language hiccup. In C# with it's great collections like List and I have: a Map class with properties of: List<byte[]> Images; List<Tile> Tiles; a Tile Class of: byte[] ImageData; int X; int Y; Now I want to add an image to the Map class and have the ImageData property of the Tile Classes to "reference" it. I have discovered I can't just assign it Images[0]. You can't have a reference to an object of a List. My fix was to create a Dictionary. Is this the best way or can I somehow have a "pointer" to a collection of objects?

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• Objective c key path operators @avg,@max .....

  - by davide

  arr = [[NSMutableArray alloc]init]; [arr addObject:[NSNumber numberWithInt:4]]; [arr addObject:[NSNumber numberWithInt:45]]; [arr addObject:[NSNumber numberWithInt:23]]; [arr addObject:[NSNumber numberWithInt:12]]; NSLog(@"The avg = %@", [arr valueForKeyPath:@"@avg.intValue"]); This code works fine, but why? valueForKeyPath:@"@avg.intValue" is requesting (int) from each NSNumber, but we are outputting a %@ string in the log. If i try to output a decimal %d i get a number that possibly is a pointer to something. Can somebody explain why the integers become NSNumbers when i call the @avg operator?

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• vector<string> or vector<char *>?

  - by Aaron

  Question: What is the difference between: vector<string> and vector<char *>? How would I pass a value of data type: string to a function, that specifically accepts: const char *? For instance: vector<string> args(argv, argv + argc); vector<string>::iterator i; void foo (const char *); //*i I understand using vector<char *>: I'll have to copy the data, as well as the pointer Edit: Thanks for input!

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• Pass 2d array to function in C?

  - by Evelyn

  I know it's simple, but I can't seem to make this work. My function is like so: int GefMain(int array[][5]) { //do stuff return 1; } In my main: int GefMain(int array[][5]); int main(void) { int array[1800][5]; GefMain(array); return 0; } I referred to this helpful resource, but I am still getting the error "warning: passing argument 1 of GefMain from incompatible pointer type." What am I doing wrong?

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• How to do "See Also" to a book using doxygen

  - by Paul J. Lucas

  The Javadoc @see allows a simple string as an argument to refer to something like a book, e.g.: @see "The Java Programming Language." As far as I can tell, the Doxygen \see offers no equivalent. Is there any way to have a book reference generated in the documentation, e.g.: See Also The C++ Programming Language, Bjarne Stroustrup, Addison-Wesley, 2000, section 19.4.1: The Standard Allocator ? Clarification This question is about how to do a "See Also" as part of a comment, e.g.: /** * Allocates memory in an amazing way. * \param size The number of bytes to allocate. * \return Returns a pointer to the start of the allocated memory. * \see MyOtherClass::alloc() * \see "The C++ Programming Language," Bjarne Stroustrup, Addison-Wesley, 2000, * section 19.4.1: The Standard Allocator. */ void* my_alloc( size_t size ); Of course the above does not work in Doxygen. Note that if there are multiple \see tags, they should be merged into a single "See Also" section (like the way \see normally works.

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• iSightAudio.plugin error when playing video using MediaPlayer

  - by Elisabeth

  I am working on creating a simple iPhone app that plays a movie via URL. When I Build&Run to test in the simulator, it works fine; as soon as I start playing the movie, I get the following message in the console: [1757:4b03] Cannot find executable for CFBundle/CFPlugIn 0x820ffe0 </Library/Audio/Plug-Ins/HAL/iSightAudio.plugin> (not loaded) [1757:4b03] Cannot find function pointer iSightAudioNewPlugIn for factory 9BE7661E-8AEF-11D7-8692-000A959F49B0 in CFBundle/CFPlugIn 0x820ffe0 </Library/Audio/Plug-Ins/HAL/iSightAudio.plugin> (not loaded) I don't get this error on other programs, so I assume it has something to do with this specific program, which uses the MediaPlayer.framework. Does anyone know what is causing this problem and how to fix it? Thank you

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• Only compiles as an array of pointers, not array of arrays

  - by Dustin

  Suppose I define two arrays, each of which have 2 elements (for theoretical purposes): char const *arr1[] = { "i", "j" }; char const *arr2[] = { "m", "n" }; Is there a way to define a multidimensional array that contains these two arrays as elements? I was thinking of something like the following, but my compiler displays warnings about incompatible types: char const *combine[][2] = { arr1, arr2 }; The only way it would compile was to make the compiler treat the arrays as pointers: char const *const *combine[] = { arr1, arr2 }; Is that really the only way to do it or can I preserve the type somehow (in C++, the runtime type information would know it is an array) and treat combine as a multidimensional array? I realise it works because an array name is a const pointer, but I'm just wondering if there is a way to do what I'm asking in standard C/C++ rather than relying on compiler extensions. Perhaps I've gotten a bit too used to Python's lists where I could just throw anything in them...

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• How to debug macruby?

  - by Dan

  Hi, I've encountered an inconsistent bug with MacRuby and have no idea how to go about debugging this. If anyone could help would be great. I don't know if this is due to my own code or is it a bug in the MacRuby framework. I have a feeling it's my own code, something about over-retaining a piece of memory and hence the garbage collection failed. This is the error from Xcode. Thanks. CSV Wizard(30245,0x7fff704f7ca0) malloc: resurrection error for object 0x20199da20 while assigning {conservative-block}[196608](0x302360060)[117616] = Array[64](0x20199da20) garbage pointer stored into reachable memory, break on auto_zone_resurrection_error to debug CSV Wizard(30245,0x103781000) malloc: garbage block 0x20199da20(Array[64]) was over-retained during finalization, refcount = 1 This could be an unbalanced CFRetain(), or CFRetain() balanced with -release. Break on auto_zone_resurrection_error() to debug. CSV Wizard(30245,0x103781000) malloc: fatal resurrection error for garbage block 0x20199da20(Array[64]): over-retained during finalization, refcount = 1

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• How to modify TList<record> value?

  - by Astronavigator

  How to modify TList < record value ? type TTest = record a,b,c:Integer end; var List:TList<TTest>; A:TTest; P:Pointer; .... .... List[10] := A; <- OK List[10].a:=1; <- Here compiler error : Left side cannot be assined to P:=@List[10]; <- Error: Variable requied

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