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  • Why is this basic equality test failing?

    - by Goose Bumper
    I have a pointer m to an object, and calling m->det() returns 14 (the return type is a double). Why would the following statement evaluate to false? cout << (m->det()==14) << endl; I just don't understand how this could be failing. Using cout << m->det() << endl; cout << (m->det()==14) << endl; gives me: 14 0

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  • C# PropertyGrid drag drop

    - by gametheoryonline
    I'm trying to implement drag/drop support to a propertygrid in C# using VS2005 (.NET 2.0). The propertygrid can handle the dragenter etc. events, but there doesn't seem to be a way to get the griditem under the pointer during a drag event. The best I've been able to get so far is to use the selectedgriditem property to retrieve a custom propertydescriptor and set the value, but this requires a grid item to already be selected before starting the drag/drop operation. Has anyone had any luck with implementing this? Thanks :-)

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  • const read only local copies

    - by robUK
    Hello gcc 4.4.4 c89 I am just wondering is it worth passing a const into a function. i.e. void do_something(const char *dest, const int size) The size is a read-only so I don't want to change it. However, some developers never have this as const has it is a local copy that is being used. The pointer is const as you can change the value in the calling routine. I always have a const on read-only local copies, as it confirms to anyone reading my code that it is a read-only variable. And also, when coding I don't make the mistake of changing it without realizing. Many thanks for any suggestions,

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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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  • 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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  • 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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  • BufferedImage Help

    - by Eddy Freeman
    I posted a question in sun java forums sometime ago and i am finding it hard to understand the first response i received from the replier though it seems he gave me the correct approach to my problem. The link to the question is: http://forums.sun.com/thread.jspa?threadID=5436562&tstart=0 Someone replied that i should use BufferedImage and make tiles. I don't really understand what the tiles mean in connection with the BufferedImage. I would like someone to explain to me what the tiles are and how they are created in the BufferedImage. I have searched the web for a while but couldn't find any link that can help me understanding the basics of the tiles and creating the tiles. Any pointer to a site is also appreciated. I need help in understanding the tiles in connection with the BufferedImage and also how they are created.

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  • function and class to show image not working in php

    - by Gully
    i am trying to get get the following working nothing is happen when i use the function i am trying to get it to display images class ItemRes { //items DB var $img=""; } function ShowItemImage($index,$res_a){ if(sizeof($res_a) > $index){ if($res_a[$index] != NULL) { $cimg = $res_a[$index]->img; return "<img src='$cimg' width='70' height='70' style='cursor:pointer'></img>"; } }else{ return "<center class='whitetxt'><strong>Empty</strong></center>"; } } $res_array = array(); $idx=0; $result21 = mysql_query("SELECT * FROM photos WHERE eid='$eid' ORDER BY id DESC") or die (mysql_error()); while ($row21 = mysql_fetch_array($result21)) { $img_path = $row21['path']; $obj = new ItemRes(); $obj->img = $img_path; $res_array[$idx] = $obj; $idx++; } ShowItemImage(0,$res_array) ShowItemImage(1,$res_array)

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  • Copying a 14bit grayscale image (saved in long[]) to a pictureBox

    - by Itsik
    My camera gives me 14bit grayscale images, but the API's function returns a long* to the image data. (so i'm assuming 4 bytes for each pixel) My application is written in C++/CLI, and the pictureBox is of .NET type. I am currently using the BitmapData.LockBits() mechanism to gain pointer access to the image data, and using memcpy(bmpData.Scan0.ToPointer(), imageData, sizeof(long)*height*width) to copy the image data to the Bitmap. For now, the only PixelFormat that is working is 32bit RGB, and the image appears in shades of blue with contours. Trying to initialize the Bitmap as 16bppGrayscale isn't working. I would ideally want to cast the array from long to word and using a 16bit format (hoping the the 14bit data will be displayed properly) but I'm not sure if this works. Also, I don't want to iterate over the image data, so finding the min/max and then histogram stretching to [0..255] isnt an option for me (the display must be as efficient as possible) Thanks

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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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  • 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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  • 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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  • What's the purpose of having a separate "operator new[]" ?

    - by sharptooth
    Looks like operator new and operator new[] have exactly the same signature: void* operator new( size_t size ); void* operator new[]( size_t size ); and do exactly the same: either return a pointer to a big enough block of raw (not initialized in any way) memory or throw an exception. Also operator new is called internally when I create an object with new and operator new[] - when I create an array of objects with new[]. Still the above two special functions are called by C++ internally in exactly the same manner and I don't se how the two calls can have different meanings. What's the purpose of having two different functions with exactly the same signatures and exactly the same behavior?

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  • Tracking EXC_BAD_ACCESS on iPad

    - by Aleks
    I've been using this code to create my UIWindow UIMyWindow* win = [[UIMyWindow alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; UIMyWindow isn't anything special it just has a pointer to a C++ class that does some wrapping of ObjectiveC. Recently my application start crashing after adding some line of code that doesn't have to do anything with the error. The line of code that I added is just allocating a C++ object but the program execution never reaches this line. Interesting enough my code works in Release. My only guess is that I made some memory corruption on a completely different place. My questions are: What type of memory corruption that can be? And is there some good practices to track them down?

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  • C -Segmentation fault after the 4th call of the function!

    - by FILIaS
    It seems at least weird to me... The program runs normally.But after I call the enter() function for the 4th time,there is a segmentation fault!I would appreciate any help. With the following function enter() I wanna add user commands' datas to a list. [Some part of the code is already posted on another question of me, but I think I should post it again...as it's a different problem I'm facing now.] /* struct for all the datas that user enters on file*/ typedef struct catalog { char short_name[50]; char surname[50]; signed int amount; char description[1000]; struct catalog *next; }catalog,*catalogPointer; catalogPointer current; catalogPointer head = NULL; void enter(void) //user command: i <name> <surname> <amount> <description> { int n,j=2,k=0; char temp[1500]; char *short_name,*surname,*description; signed int amount; char* params = strchr(command,' ') + 1; //strchr returns a pointer to the 1st space on the command.U want a pointer to the char right after that space. strcpy(temp, params); //params is saved as temp. char *curToken = strtok(temp," "); //strtok cuts 'temp' into strings between the spaces and saves them to 'curToken' printf("temp is:%s \n",temp); printf("\nWhat you entered for saving:\n"); for (n = 0; curToken; ++n) //until curToken ends: { if (curToken) { short_name = malloc(strlen(curToken) + 1); strncpy(short_name, curToken, sizeof (short_name)); } printf("Short Name: %s \n",short_name); curToken = strtok(NULL," "); if (curToken) { surname = malloc(strlen(curToken) + 1); strncpy(surname, curToken,sizeof (surname)); } printf("SurName: %s \n",surname); curToken = strtok(NULL," "); if (curToken) { //int * amount= malloc(sizeof (signed int *)); char *chk; amount = (int) strtol(curToken, &chk, 10); if (!isspace(*chk) && *chk != 0) fprintf(stderr,"Warning: expected integer value for amount, received %s instead\n",curToken); } printf("Amount: %d \n",amount); curToken = strtok(NULL,"\0"); if (curToken) { description = malloc(strlen(curToken) + 1); strncpy(description, curToken, sizeof (description)); } printf("Description: %s \n",description); break; } if (findEntryExists(head, surname,short_name) != NULL) //call function in order to see if entry exists already on the catalog printf("\nAn entry for <%s %s> is already in the catalog!\nNew entry not entered.\n",short_name,surname); else { printf("\nTry to entry <%s %s %d %s> in the catalog list!\n",short_name,surname,amount,description); newEntry(&head,short_name,surname,amount,description); printf("\n**Entry done!**\n"); } // Maintain the list in alphabetical order by surname. } catalogPointer findEntryExists (catalogPointer head, char num[],char first[]) { catalogPointer p = head; while (p != NULL && strcmp(p->surname, num) != 0 && strcmp(p->short_name,first) != 0) { p = p->next; } return p; } catalogPointer newEntry (catalog** headRef,char short_name[], char surname[], signed int amount, char description[]) { catalogPointer newNode = (catalogPointer)malloc(sizeof(catalog)); catalogPointer first; catalogPointer second; catalogPointer tmp; first=head; second=NULL; strcpy(newNode->short_name, short_name); strcpy(newNode->surname, surname); newNode->amount=amount; strcpy(newNode->description, description); //SEGMENTATION ON THE 4TH RUN OF PROGRAM STOPS HERE depending on the names each time it gets! while (first!=NULL) { if (strcmp(surname,first->surname)>0) second=first; else if (strcmp(surname,first->surname)==0) { if (strcmp(short_name,first->short_name)>0) second=first; } first=first->next; } if (second==NULL) { newNode->next=head; head=newNode; } else { tmp=second->next; newNode->next=tmp; first->next=newNode; } }

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  • Assigning a view controller to be the delegate of a subview which is not directly descendent?

    - by ambertch
    I am writing an iphone app where in numerous cases a subview needs to talk to its superview. For example: View A has a table view that contains photos A has a subview B which allows users to add photos, upon which I want to auto append them to A's table view So far I have been creating a @protocol in B, and registering A as the delegate. The problem in my case is that B has a subview C that allows users to add content, and I want actions in C to invoke changes in its grandparent, A. Currently I am working around this by passing around a self pointer to my base view controller (C.delegate = B.delegate), but it doesn't seem very proper to me. Any thoughts? (and/or general advice on code organization when all sort of subviews needs to talk to superviews would be greatly appreciated) Thanks!

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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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  • Ways to divide the high/low byte from a 16bit address?

    - by Grissiom
    Hello, I'm developing a software on 8051 processor. A frequent job is to divide the high and low byte of a 16bit address. I want to see there are how many ways to achieve it. The ways I come up so far are: (say ptr is a 16bit pointer, and int is 16bit int) ADDH = (unsigned int) ptr >> 8; ADDL = (unsigned int) ptr & 0x00FF; and ADDH = ((unsigned char *)&ptr)[0]; ADDL = ((unsigned char *)&ptr)[1]; Does anyone have any other bright ideas? ;) And anyone can tell me which way is more efficient?

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  • doubt in sizeof implementation

    - by aks
    Below is the program to find the size of a structure without using sizeof operator: struct MyStruct { int i; int j; }; int main() { struct MyStruct *p=0; int size = ((char*)(p+1))-((char*)p); printf("\nSIZE : [%d]\nSIZE : [%d]\n", size); return 0; } My doubt is: Why is typecasting to char * required? If I don't use the char* pointer, the output is 1 - WHY?

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  • Same code... but warning!Any ideas?

    - by FILIaS
    I've a question for a warning message that i get. For this line,using qsort: qsort(catalog, MAX ,sizeof catalog, struct_cmp_by_amount); I get this warning: warning: passing argument 4 of ‘qsort’ makes pointer from integer without a cast struct_cmp_by_amount is another function on the program. BUT,for another program with the same code, with the same exactly struct_cmp_by_amount function, i dont get that warning for the 4th argument! qsort(structs, structs_len, sizeof(struct st_ex), struct_cmp_by_price); I'm wandering about why that;s happening. Have you any idea?

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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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  • 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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  • UISearchDisplayController automatically creates a UIPopovercontroller to display content search result ?! How to dismiss it ?

    - by yonel
    Hi, I'm using a UISearchDisplayController with a UISearchBar. I put this UISearchBar in my app using IB and I get : Fine : when you start taping, the result popovercontroller appears magically (I didn't write anything on my own to make it appear !) Then, when a row is clicked among the result, I want to dismiss the PopoverController BUT at this stage, I never instantiated the UIPopoverController on my side : it looks like if there's an encapsulated behavior in the UISearchDisplayController that automatically wraps its searchContentsController inside a UIPopoverController. That's really great because everything works perfectly without doing anything except that I cannot get the reference to this UIPopoverController to dismiss it :( Does anyone know how to get the reference to this "magically" created UIPopoverController ? (this is the proof the iPad is really a "magical" device ;) I thought there would be a reference to the UIPopoverController from its contentController (through its parent property for instance), but I cannot find any way to get a pointer to it :/

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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 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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