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  • Is it safe to catch an access violation in this scenario?

    - by Eloff
    I've read a lot, including here on SO that suggests this is a very bad idea in general and that the only thing you can do safely is exit the program. I'm not sure that this is true. This is for a pooling memory allocator that hands off large allocations to malloc. During pool_free() a pointer needs to be checked it it belongs to a pool or was allocated with malloc. By rounding the address down to the nearest 1MB boundary, I get a pointer to the beginning of a block of memory in the pool, or undefined if malloc was used. In the first case I can easily verify that the block of memory belongs to the pool, but, if it does not I will either fail this verification, or I will get an access violation (note that this is a read-only process). Could I not catch this with SEH (Windows) or handle the signal (POSIX) and simply treat it as a failed verification? (i.e. this is only possible if malloc was used, so pass the ptr to free())

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  • const TypedeffedIntPointer not equal to const int *

    - by dirk
    I have the following C++ code: typedef int* IntPtr; const int* cip = new int; const IntPtr ctip4 = cip; I compile this with Visual Studio 2008 and get the following error: error C2440: 'initializing' : cannot convert from 'const int *' to 'const IntPtr' Clearly my understanding of typedefs is not what is should be. The reason I'm asking, I'm storing a pointer type in a STL map. I have a function that returns a const pointer which I would like to use to search in the map (using map::find(const key_type&). Since const MyType* and const map<MyType*, somedata>::key_type is incompatible, I'm having problems. Regards Dirk

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  • Resize an array of images with OpenCV

    - by amr
    I'm passing an array of images (IplImage**) to an object in C++ using OpenCV. I'm then trying to iterate over that array and resize them all to a fixed size (150x150) I'm doing it this way: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[0]->depth, this->faceImageArray[0]->nChannels ); cout << "Created image" << endl; cvResize(this->faceImageArray[i], frame_copy); cout << "Resized image" << endl; IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cout << "Created grey image" << endl; cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); cout << "Converted image" << endl; this->faceImageArray[i] = grey_image; cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } But I'm getting this output, and I'm not sure why: Created image Resized image Created grey image Converted image Created image OpenCV Error: Assertion failed (src.type() == dst.type()) in cvResize, file /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp, line 3102 terminate called after throwing an instance of 'cv::Exception' what(): /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp:3102: error: (-215) src.type() == dst.type() in function cvResize Aborted I'm basically just trying to replace the image in the array with the resized one in as few steps as possible. Edit: Revised my code as follows: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[i]->depth, this->faceImageArray[i]->nChannels ); cvResize(this->faceImageArray[i], frame_copy); IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); faceImageArray[i] = cvCreateImage( cvSize(grey_image->width, grey_image->height), grey_image->depth, grey_image->nChannels); cvCopy(grey_image,faceImageArray[i]); cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } Then later on I'm performing some PCA, and get this output: OpenCV Error: Null pointer (Null pointer to the written object) in cvWrite, file /build/buildd/opencv-2.1.0/src/cxcore/cxpersistence.cpp, line 4740 But I don't think my code has got to the point where I'm explicitly calling cvWrite, so it must be part of the library. I can give a full implementation if necessary - is there anything in my code that's going to create a null pointer?

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  • Is this a valid css?

    - by Pandiya Chendur
    I have a pager in my page with anchors in it... I use the following css... .page-numbers a { color:#808185; cursor:pointer; text-decoration:none;outline:none; } .page-numbers a:hover { text-decoration:underline; } .page-numbers a:visited { color:#808185;outline:none; } But my anchor tag doesn't seem to take the css above instead it uses the css below, a { color:#0077CC; cursor:pointer; text-decoration:none;outline:none; } a:hover { text-decoration:underline; } a:visited { color:#4A6B82;outline:none; } Which i have given in the top of my stylesheet... Any suggestion...

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  • Why must "stride" in the System.Drawing.Bitmap constructor be a multiple of 4?

    - by Gorchestopher H
    I am writing an application that requires me to take a proprietary bitmap format (an MVTec Halcon HImage) and convert it into a System.Drawing.Bitmap in C#. The only proprietary functions given to me to help me do this involve me writing to file, except for the use of a "get pointer" function. This function is great, it gives me a pointer to the pixel data, the width, the height, and the type of the image. My issue is that when I create my System.Drawing.Bitmap using the constructor: new System.Drawing.Bitmap(width, height, stride, format, scan) I need to specify a "stride" that is a multiple of 4. This may be a problem as I am unsure what size bitmap my function will be hit with. Supposing I end up with a bitmap that is 111x111 pixels, I have no way to run this function other than adding a bogus column to my image or subtracting 3 columns. Is there a way I can sneak around this limitation?

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  • GWT AbstractColumnDefinition (Need to add style to certain Columns)

    - by Mario
    I have a column Definition for each colume that extends AbstractColumnDefinition these columns are put in a DefaultTableDefinition. example: NAME | SIZE | RES | DELETE | this style (AT THE END OF THE PAGE ) is added to the column names if you notice all of them are with a cursor pointer , meaning a hand shows up when i hover above each one. my question is would I be able to remove the coursor for delete or in general for a certain column and keeping it for another one .. i tried to do that with each column Definition but there is no such thing as remove or addstyle even to like put my own style. THANK YOU .gwt-ScrollTable .headerTable td { border-bottom:1px solid black; border-left:1px solid #CCCCCC; border-right:1px solid #CCCCCC; cursor:pointer; vertical-align:bottom; }

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  • Effective methods for reading and writing large files in C

    - by Bertholt Stutley Johnson
    I'm writing an application that deals with very large user-generated input files. The program will copy about 95 percent of the file, effectively duplicating it and switching a few words and values in the copy, and then appending the copy (in chunks) to the original file, such that each block (consisting of between 10 and 50 lines) in the original is followed by the copied and modified block, and then the next original block, and so on. The user-generated input conforms to a certain format, and it is highly unlikely that any line in the original file is longer than 100 characters long. Which would be the better approach? a) To use one file pointer and use variables that hold the current position of how much has been read and where to write to, seeking the file pointer back and forth to read and write; or b) To use multiple file pointers, one for reading and one for writing. I am mostly concerned with the efficiency of the program, as the input files will reach up to 25,000 lines, each about 50 characters long. Thanks!

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  • is my function correct?

    - by sbsp
    This is part of an assignment so please dont post solutions, just point me in the right direction if possible? I am passing a pointer to a char array to my method, as well as a value for the actual height of the char array. I am looping through to see if all values are 0, if they are then return 0, esle return one The method is used as a test to see if i should free memory or not and set the pointer to null if it is full of 0's. The issue i am having is that the programme should have "some unfree" memory at the end, so i have no idea whether or not its doing it correctly - and gdb i struggle with immensley. Thanks for reading int shouldBeNull(char *charPointer, int sizeOfCharArray) { int isIn = 0; int i = 0; while(i < sizeOfCharArray){ if(*charPointer != '0'){ isIn = 1; break; } i++; charPointer++; } return isIn; }

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  • CSS background image inconsistency in IE6 and IE7

    - by The Machine
    I have a span that is generated through javascript, with its css class as follows: .class1{ width:25px; height:25px; background-image: url(pic.png); background-repeat:no-repeat; background-position: center; cursor:pointer; margin-left:10px; } The problem is on, the html page, i can see the pointer -cursor, but not the background image,over the span, in IE7. In IE6, both get shown , no problems.

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  • Is there an easy way to make `boost::ptr_vector` more debugger friendly in Visual Studio?

    - by Billy ONeal
    I'm considering using boost::ptr_container as a result of the responses from this question. My biggest problem with the library is that I cannot view the contents of the collection in the debugger, because the MSVC debugger doesn't recognize it, and therefore I cannot see the contents of the containers. (All the data gets stored as void * internally) I've heard MSVC has a feature called "debugger visualizers" which would allow the user to make the debugger smarter about these kinds of things, but I've never written anything like this, and I'm not hugely firmiliar with such things. For example, compare the behavior of boost::shared_ptr with MSVC's own std::tr1::shared_ptr. In the debugger (i.e. in the Watch window), the boost version shows up as a big mess of internal variables used for implementing the shared pointer, but the MSVC version shows up as a plain pointer to the object (and the shared_ptr's innards are hidden). How can I get started either using or implementing such a thing?

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  • How to obtain Bing maps like InfoWindow in Google Maps?

    - by BillB
    I'm using Google Maps v3. I really like the InfoWindows found in Bing, as opposed to Google. Screenshots & functionality found here comparing the two: http://www.axismaps.com/blog/2009/07/data-probing-and-info-window-design-on-web-based-maps/ Question: How can I replicate Bing like InfoWindows while using Google Maps v3? UPDATE: To be more specific, what I like about Bing's InfoWindows include: - The pointer dynamically changes sides from left/right/bottom/top, as opposed to Google limited to only have the InfoWindow pointer on the bottom - Bing's InfoWindows use less space - You can configure Bing's InfoWindows to pop up outside of the map bounders so that you don't have to autopan the map to display the marker's InfoWindow

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  • Why doesn't this code work correctly?

    - by MisterSir
    I'm working on a website that displays galleries, using jCarousel. But no matter what I try, I can't get it to work, and I need to finish this by today. I have a very urgent schedule. My code basically takes image URLs from a database and sends them to AJAX, which passes it to jCarousel which makes the gallery. But there are a few problems: It doesn't display correctly! I can only get the last item pulled from the database, and it displays on the bottom-most row. After the item pulled from the database is displayed, the first time I click on "prev" there's no scroll effect, and the item just disappears! Only if I click on "next" 2-3 times there's a scroll effect and the item remains visible. My items are always displayed at the end of the carousel! This is urgent.. Please help me fix this. about.html: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-us"> <head> <script type="text/javascript" src="jquery-1.4.4.min.js"></script> <script type="text/javascript" src="/lib/jquery.jcarousel.min.js"></script> <link rel="stylesheet" type="text/css" href="/skins/tango/skin.css" /> <!--<style type="text/css"> #wrapper { width: 700px; margin-left: auto; margin-right: auto; } #carousel { margin-top: 120px; padding-left: 120px; } #side { padding-left: 550px; position: absolute; padding-top: 120px; } #hidden { color: #FFFFFF; } </style>--> <script type="text/javascript"> jQuery.easing['BounceEaseOut'] = function(p, t, b, c, d) { if ((t/=d) < (1/2.75)) { return c*(7.5625*t*t) + b; } else if (t < (2/2.75)) { return c*(7.5625*(t-=(1.5/2.75))*t + .75) + b; } else if (t < (2.5/2.75)) { return c*(7.5625*(t-=(2.25/2.75))*t + .9375) + b; } else { return c*(7.5625*(t-=(2.625/2.75))*t + .984375) + b; } }; function mycarousel_initCallback(carousel) { jQuery('#mycarousel-next').bind('click', function() { carousel.next(); return false; }); jQuery('#mycarousel-prev').bind('click', function() { carousel.prev(); return false; }); }; jQuery(document).ready(function() { jQuery('#mycarousel').jcarousel({ easing: 'BounceEaseOut', wrap: "first", initCallback: mycarousel_initCallback, animation: 1000, scroll: 3, visible: 3, buttonNextHTML: null, buttonPrevHTML: null }); jQuery('#mycarousel2').jcarousel({ easing: 'BounceEaseOut', animation: 1000, wrap: "first", initCallback: mycarousel_initCallback, scroll: 3, visible: 3, buttonNextHTML: null, buttonPrevHTML: null }); jQuery('#mycarousel3').jcarousel({ easing: 'BounceEaseOut', animation: 1000, scroll: 3, wrap: "first", initCallback: mycarousel_initCallback, visible: 3, buttonNextHTML: null, buttonPrevHTML: null }); }); var prevButton = null; function getObject(b, el) { var currbutton = b; var http; var url = "about.php"; var parameters = "d=carousel&cat=" + currbutton; try { http = new XMLHttpRequest(); } catch(e) { try { http = new ActiveXObject("Msxml2.XMLHTTP"); } catch(e) { http = new ActiveXObject("Microsoft.XMLHTTP"); } } function getServer() { if (http.readyState == 4) { var i = 0; var liArr = http.responseText; var built = liArr.split(", "); var li = document.createElement("li"); var ul1 = document.getElementById("mycarousel"); var ul2 = document.getElementById("mycarousel2"); var ul3 = document.getElementById("mycarousel3"); if (el != prevButton) { prevButton = el; while (ul1.hasChildNodes() ) {ul1.removeChild(ul1.lastChild);} while (ul2.hasChildNodes() ) {ul2.removeChild(ul2.lastChild);} while (ul3.hasChildNodes() ) {ul3.removeChild(ul3.lastChild);} } else return 0; while (i < (built.length) / 3) { li.innerHTML = built[i]; ul1.appendChild(li); i++; } while (i < ((built.length) / 3)*2) { li.innerHTML = built[i]; ul2.appendChild(li); i++; } while (i < (built.length)) { li.innerHTML = built[i]; ul3.appendChild(li); i++; } } } http.open("POST", url, true); http.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); http.setRequestHeader("Content-length", parameters.length); http.setRequestHeader("Connection", "close"); http.onreadystatechange = getServer; http.send(parameters); } </script> </head> <body> <span id="hidden"> </span> <div id="wrapper"> <div id="side"> <form name="cats"> <input type="button" value="Hats" onclick="getObject('hats', this);"/><br /> <input type="button" value="Pants" onclick="getObject('pants', this);"/><br /> <input type="button" value="Shirts" onclick="getObject('shirts', this);"/><br /> </form> </div> <div id="carousel"> <ul id="mycarousel" class="jcarousel-skin-tango"> </ul> <ul id="mycarousel2" class="jcarousel-skin-tango"> </ul> <ul id="mycarousel3" class="jcarousel-skin-tango"> </ul> <input type="button" id="mycarousel-prev" value="prev" /> <input type="button" id="mycarousel-next" value="next" /> </div> </div> </body> </html> I commented the CSS because I thought it was giving me trouble, but honestly I have no idea what the hell's going on with jCarousel. about.php: <?php echo "<img width='75' height='75' src='http://static.flickr.com/66/199481236_dc98b5abb3_s.jpg' />, hi, hi, hi, hi, hi, hi, hi, hi"; ?> Also, even if there are no other items than what is displayed, I'm still able to scroll back, but not forward, assumingly because my item is always placed at the end of the carousel. I know it looks like a lot of code but it's really not! My formatting takes a lot of lines, the commented CSS takes a lot, and a lot of the code is HTML and jCarousel configuration, and there's also the BounceEasing effect which takes a few lines. There's not much actual code! So as I said, this is urgent and I need this fixed. But I can't get it to work. Please help me! Thanks for your time! EDIT: I changed the code a bit, but it still does not work. I really need help on this one!! EDIT: I added document.createElement("li"); to each while loop. Now all my items are displayed, but they are displayed vertically and not horizontally on each row. Other than that all other problems are the same. EDIT: Oh and also, in the row my image displays, only the image is there. Maybe jCarousel doesn't accept img and text, I don't know.

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  • global std::unordered_map com server init problems

    - by PrettyFlower
    I want to have a static global std::unordered_map in the cpp of my entry point for my COM server. relevant header code: typedef unordered_map<HWND,IMyInterface*> MyMapType; relevant body: static MyMapType MyMap; void MyFunction(HWND hWnd, IMyInterface* pObj){ MyMap[HWND] = pObj; } HINSTANCE g_hInstModule = NULL; BOOL WINAPI DllMain ( __in HINSTANCE hInstDLL, __in DWORD fdwReason, __in LPVOID lpvReserved ) { if( fdwReason == DLL_PROCESS_ATTACH ) { g_hInstModule = hInstDLL; return true; } else if( fdwReason == DLL_PROCESS_DETACH ) { return true; } return false; } MyCoClass::MyCoClass() { DRM_Refcount = 1; } HRESULT STDMETHODCALLTYPE MyCoClass::InitMyCoClass() { CoInitializeEx(NULL, COINIT_APARTMENTTHREADED); //replace with make window code MyFunction(hWnd,ISomeInterface); return S_OK; } The only way I can get this to work is be making a map_type pointer and creating an instance of map_type on the heap and pointing at it with the global pointer. :/ WHY?

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  • user defined Copy ctor, and copy-ctors further down the chain - compiler bug ? programmers brainbug

    - by J.Colmsee
    Hi. i have a little problem, and I am not sure if it's a compiler bug, or stupidity on my side. I have this struct : struct BulletFXData { int time_next_fx_counter; int next_fx_steps; Particle particles[2];//this is the interesting one ParticleManager::ParticleId particle_id[2]; }; The member "Particle particles[2]" has a self-made kind of smart-ptr in it (resource-counted texture-class). this smart-pointer has a default constructor, that initializes to the ptr to 0 (but that is not important) I also have another struct, containing the BulletFXData struct : struct BulletFX { BulletFXData data; BulletFXRenderFunPtr render_fun_ptr; BulletFXUpdateFunPtr update_fun_ptr; BulletFXExplosionFunPtr explode_fun_ptr; BulletFXLifetimeOverFunPtr lifetime_over_fun_ptr; BulletFX( BulletFXData data, BulletFXRenderFunPtr render_fun_ptr, BulletFXUpdateFunPtr update_fun_ptr, BulletFXExplosionFunPtr explode_fun_ptr, BulletFXLifetimeOverFunPtr lifetime_over_fun_ptr) :data(data), render_fun_ptr(render_fun_ptr), update_fun_ptr(update_fun_ptr), explode_fun_ptr(explode_fun_ptr), lifetime_over_fun_ptr(lifetime_over_fun_ptr) { } /* //USER DEFINED copy-ctor. if it's defined things go crazy BulletFX(const BulletFX& rhs) :data(data),//this line of code seems to do a plain memory-copy without calling the right ctors render_fun_ptr(render_fun_ptr), update_fun_ptr(update_fun_ptr), explode_fun_ptr(explode_fun_ptr), lifetime_over_fun_ptr(lifetime_over_fun_ptr) { } */ }; If i use the user-defined copy-ctor my smart-pointer class goes crazy, and it seems that calling the CopyCtor / assignment operator aren't called as they should. So - does this all make sense ? it seems as if my own copy-ctor of struct BulletFX should do exactly what the compiler-generated would, but it seems to forget to call the right constructors down the chain. compiler bug ? me being stupid ? Sorry about the big code, some small example could have illustrated too. but often you guys ask for the real code, so well - here it is :D EDIT : more info : typedef ParticleId unsigned int; Particle has no user defined copyctor, but has a member of type : Particle { .... Resource<Texture> tex_res; ... } Resource is a smart-pointer class, and has all ctor's defined (also asignment operator) and it seems that Resource is copied bitwise. EDIT : henrik solved it... data(data) is stupid of course ! it should of course be rhs.data !!! sorry for huge amount of code, with a very little bug in it !!! (Guess you shouldn't code at 1 in the morning :D )

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  • Viewing array of pointers to structures in Visual Studio in the debugger

    - by Fozi
    I'm having a problem displaying the contents of a pointer array with its contents in the debugger. If I just add the pointer to the watch only the fist entry is visible. But if I add the length to it the debugger assumes that I have something like array[length][length]. Picture The first entry is the broken one, looks the same with ,2 or with any ,2 x. The second one is what I would like to see, but for more entries. Edit: The two entries displayed as [x][1] are invalid. I'm using VS 2005 but I think I had this problem on 2008 as well. Is this a bug or am I doing something wrong?

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  • Test, if object was deleted

    - by justik
    Look to the following code, please: class Node { private: double x, y; public: Node (double xx, double yy): x(xx), y(yy){} }; int main() { Node *n1 = new Node(1,1); Node *n2 = n1; delete n2; n2 = NULL; if (n1 != NULL) //Bad test { delete n1; //throw an exception } } There are two pointers n1, n2 pointed to the same object. I would like to detect whether n2 was deleted using n1 pointer test. But this test results in exception. Is there any way how to determine whether the object was deleted (or was not deleted) using n1 pointer ? Thanks for your help.

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  • Why C++ virtual function defined in header may not be compiled and linked in vtable?

    - by 0xDEAD BEEF
    Situation is following. I have shared library, which contains class definition - QueueClass : IClassInterface { virtual void LOL() { do some magic} } My shared library initialize class member QueueClass *globalMember = new QueueClass(); My share library export C function which returns pointer to globalMember - void * getGlobalMember(void) { return globalMember;} My application uses globalMember like this ((IClassInterface*)getGlobalMember())->LOL(); Now the very uber stuff - if i do not reference LOL from shared library, then LOL is not linked in and calling it from application raises exception. Reason - VTABLE contains nul in place of pointer to LOL() function. When i move LOL() definition from .h file to .cpp, suddenly it appears in VTABLE and everything works just great. What explains this behavior?! (gcc compiler + ARM architecture_)

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  • Convert NSData into Hex NSString

    - by Dawson
    With reference to the following question: Convert NSData into HEX NSSString I have solved the problem using the solution provided by Erik Aigner which is: NSData *data = ...; NSUInteger capacity = [data length] * 2; NSMutableString *stringBuffer = [NSMutableString stringWithCapacity:capacity]; const unsigned char *dataBuffer = [data bytes]; NSInteger i; for (i=0; i<[data length]; ++i) { [stringBuffer appendFormat:@"%02X", (NSUInteger)dataBuffer[i]]; } However, there is one small problem in that if there are extra zeros at the back, the string value would be different. For eg. if the hexa data is of a string @"3700000000000000", when converted using a scanner to integer: unsigned result = 0; NSScanner *scanner = [NSScanner scannerWithString:stringBuffer]; [scanner scanHexInt:&result]; NSLog(@"INTEGER: %u",result); The result would be 4294967295, which is incorrect. Shouldn't it be 55 as only the hexa 37 is taken? So how do I get rid of the zeros? EDIT: (In response to CRD) Hi, thanks for clarifying my doubts. So what you're doing is to actually read the 64-bit integer directly from a byte pointer right? However I have another question. How do you actually cast NSData to a byte pointer? To make it easier for you to understand, I'll explain what I did originally. Firstly, what I did was to display the data of the file which I have (data is in hexadecimal) NSData *file = [NSData dataWithContentsOfFile:@"file path here"]; NSLog(@"Patch File: %@",file); Output: Next, what I did was to read and offset the first 8 bytes of the file and convert them into a string. // 0-8 bytes [file seekToFileOffset:0]; NSData *b = [file readDataOfLength:8]; NSUInteger capacity = [b length] * 2; NSMutableString *stringBuffer = [NSMutableString stringWithCapacity:capacity]; const unsigned char *dataBuffer = [b bytes]; NSInteger i; for (i=0; i<[b length]; ++i) { [stringBuffer appendFormat:@"%02X", (NSUInteger)dataBuffer[i]]; } NSLog(@"0-8 bytes HEXADECIMAL: %@",stringBuffer); As you can see, 0x3700000000000000 is the next 8 bytes. The only changes I would have to make to access the next 8 bytes would be to change the value of SeekFileToOffset to 8, so as to access the next 8 bytes of data. All in all, the solution you gave me is useful, however it would not be practical to enter the hexadecimal values manually. If formatting the bytes as a string and then parsing them is not the way to do it, then how do I access the first 8 bytes of the data directly and cast them into a byte pointer?

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  • What is the safest way to pass strings around in C?

    - by chucknelson
    I have a program in C using Solaris with VERY ancient compatibility it seems. Many examples, even here on SO, don't work, as well as lots of code I've written on Mac OS X. So when using very strict C, what is the safest way to pass strings? I'm currently using char pointers all over the place, due to what I thought was simplicity. So I have functions that return char*, I'm passing char* to them, etc. I'm already seeing strange behavior, like a char* I passed having its value right when I enter a function, and then the value being mysteriously gone OR corrupted/overwritten after something simple like one printf() or an malloc to some other pointer. I was thinking maybe declaring a local char[] inside each function, using strcpy() immediately, and then eventually returning a pointer where char *returnval = strdup(localchar[]); This seems...sloppy. Can anyone point me in the right direction on a simple requirement?

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  • fread() behaves weird

    - by Cres
    hi, I have a problem in a C program of mine where after I use fread(), the file pointer goes to the end of the file sometimes. I'll try to explain better - the code looks something like: dummy = ftell(fp); fread(&buf, sizeof(unsigned char), 8, fp); dummy = ftell(fp); where fp is a file pointer to an opened file (opened it with "w+", I'm using it as a binary file and I know i'm supposed to have a "b" in there too, but I heard its not really important to add it..), dummy is just an unsigned long variable, and buf is unsigned char[8] now, when debugging, at the ftell before the fread, dummy is 262062 at the ftell after the fread, dummy is 262640 even though I only 'moved' 8 bytes.. does anyone have any idea what can be the cause of this..? thanks for your help :)

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  • Why doesn't this work?

    - by user146780
    I'v tried to solve a memory leak in the GLU callback by creating a global variable but now it dos not draw anything: GLdouble *gluptr = NULL; void CALLBACK combineCallback(GLdouble coords[3], GLdouble *vertex_data[4], GLfloat weight[4], GLdouble **dataOut) { GLdouble *vertex; if(gluptr == NULL) { gluptr = (GLdouble *) malloc(6 * sizeof(GLdouble)); } vertex = (GLdouble*)gluptr; vertex[0] = coords[0]; vertex[1] = coords[1]; vertex[2] = coords[2]; for (int i = 3; i < 6; i++) { vertex[i] = weight[0] * vertex_data[0][i] + weight[1] * vertex_data[0][i] + weight[2] * vertex_data[0][i] + weight[3] * vertex_data[0][i]; } *dataOut = vertex; } basically instead of doing malloc each time in the loop (thus the memory leak) im using a global pointer, but this doesn't work (drawing to the screen). Why would using malloc to a pointer created in the function work any different than a global variable? Thanks

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  • Static source code analysis with LLVM

    - by Phong
    I recently discover the LLVM (low level virtual machine) project, and from what I have heard It can be used to performed static analysis on a source code. I would like to know if it is possible to extract the different function call through function pointer (find the caller function and the callee function) in a program. I could find the kind of information in the website so it would be really helpful if you could tell me if such an library already exist in LLVM or can you point me to the good direction on how to build it myself (existing source code, reference, tutorial, example...). EDIT: With my analysis I actually want to extract caller/callee function call. In the case of a function pointer, I would like to return a set of possible callee. both caller and callee must be define in the source code (this does not include third party function in a library).

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