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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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• 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 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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• 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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• 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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• 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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• 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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• Perl, treat string as binary byte array

  - by Mike

  In Perl, is it appropriate to use a string as a byte array containing 8-bit data? All the documentation I can find on this subject focuses on 7-bit strings. For instance, if I read some data from a binary file into $data my $data; open FILE, "<", $filepath; binmode FILE; read FILE $data 1024; and I want to get the first byte out, is substr($data,1,1) appropriate? (again, assuming it is 8-bit data) I come from a mostly C background, and I am used to passing a char pointer to a read() function. My problem might be that I don't understand what the underlying representation of a string is in Perl.

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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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• 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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• 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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• 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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• Swap bits in c++ for a double

  - by hidayat

  Im trying to change from big endian to little endian on a double. One way to go is to use double val, tmp = 5.55; ((unsigned int *)&val)[0] = ntohl(((unsigned int *)&tmp)[1]); ((unsigned int *)&val)[1] = ntohl(((unsigned int *)&tmp)[0]); But then I get a warning: "dereferencing type-punned pointer will break strict-aliasing rules" and I dont want to turn this warning off. Another way to go is: #define ntohll(x) ( ( (uint64_t)(ntohl( (uint32_t)((x << 32) >> 32) )) << 32) | ntohl( ((uint32_t)(x >> 32)) ) ) val = (double)bswap_64(unsigned long long(tmp)); //or val = (double)ntohll(unsigned long long(tmp)); But then a lose the decimals. Anyone know a good way to swap the bits on a double without using a for loop?

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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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• JQuery Autocomplete - Stop mouseover+Return submitting data

  - by ILT

  I'm using JQuery Autocomplete (bassistance) and have run into a problem. If the mouse rolls over one of the autocomplete suggestions and the user hits the return key (rather than clicking to make selection), the form is submitted and goes to whatever link was rolled over at the time. This is a problem as people click in the textbox, and when typing their search, leave the pointer where the autocomplete popup appears. So when they hit enter, it doesn't do the search for whatever they typed in the box but whatever was highlighted in the autocomplete suggestions. Is there a way to stop this? Using Google as the functionality I'm after... So just to clarify - I want selections via mouse and keyboard to go to the same place, but if the UP or DOWN arrow has not been pressed (user not selected an autocomplete option via the keyword), dont go to the URL specified in the autosuggest - instead submit the form (traditional method without JQuery) based on what has been typed in the textbox. I hope I'm explaining this clearly? :S

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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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• 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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• How do I draw an arrow on a histogram drawn using ggplot2?

  - by jon

  Here is dataset: set.seed(123) myd <- data.frame (class = rep(1:4, each = 100), yvar = rnorm(400, 50,30)) require(ggplot2) m <- ggplot(myd, aes(x = yvar)) p <- m + geom_histogram(colour = "grey40", fill = "grey40", binwidth = 10) + facet_wrap(~class) + theme_bw( ) p + opts(panel.margin=unit(0 ,"lines")) I want to add labels to bars which each subject class fall into and produce something like the post-powerpoint processed graph. Is there way to do this within R ? ...... Edit: we can think of different pointer such as dot or error bar, if arrow is not impossible Let's say the following is subjects to be labelled: class name yvar 2 subject4 104.0 3 subject3 8.5 3 subject1 80.0 4 subject2 40.0 4 subject1 115.0 classd <- data.frame (class = c(2,3,3,4,4), name = c ("subject4", "subject3", "subject1", "subject2", "subject1"), yvar = c(104.0, 8.5,80.0,40.0, 115.0))

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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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• 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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• 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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• How to signal a buffer full state between posix threads

  - by mikip

  Hi I have two threads, the main thread 'A' is responsible for message handling between a number of processes. When thread A gets a buffer full message, it should inform thread B and pass a pointer to the buffer which thread B will then process. When thread B has finished it should inform thread A that it has finished. How do I go about implementing this using posix threads using C on linux. I have looked at conditional variables, is this the way to go? . I'm not experienced in multi threaded programming and would like some advice on the best avenue to take. Thanks

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• use callback function to report stack backtrace

  - by user353394

  Assume I have the following: typedef struct { char *name; char binding; int address; } Fn_Symbol //definition of function symbol static Fn_Symbol *fnSymbols; //array of function symbols in a file statc int total; //number of symbol functions in the array and file static void PrintBacktrace(int sigum, siginfo_t * siginfo, void *context) { printf("\nSignal received %d (%s)\n", signum, strsignal(signum)); const int eip_index = 14; void *eip = (void *)((struct ucontext *)context)->uc_mcontext.gregs[eip_index]; printf("Error at [%p] %s (+0x%x), eip, fnName, offset from start); //????? exit(0); } I have this so far, but what is the best way using the fnSymbols static global pointer to identify the function where the error occured and then back trace through the stack to identify each calling function by address, name, and offset?

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• How to name variables wich are structs

  - by evilpie

  Hello, i often work on private projects using the WinApi, and as you might know, it has thousands of named and typedefed structs like MEMORY_BASIC_INFORMATION. I will stick to this one in my question, what still is preferred, or better when you want to name a variable of this type. Is there some kind of style guide for this case? For example if i need that variable for the VirtualQueryEx function. Some ideas: MEMORY_BASIC_INFORMATION memoryBasicInformation; MEMORY_BASIC_INFORMATION memory_basic_information; Just use the name of the struct non captialized and with or without the underlines. MEMORY_BASIC_INFORMATION basicInformation; MEMORY_BASIC_INFORMATION information; Short form? MEMORY_BASIC_INFORMATION mbi; I often see this style, using the abbreviation of the struct name. MEMORY_BASIC_INFORMATION buffer; VirtualQueryEx defines the third parameter lpBuffer (where you pass the pointer to the struct), so using this name might be an idea, too. Cheers

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• How do I modify the -encoding argument to javac in the Android Ant build system

  - by Paul Butcher

  Apologies if this is a stupid question - I'm an Android and Ant newbie. I have utf8 encoded source files that I need to compile with the Android Ant build system. By default, the encoding is set to ascii. I'd be very grateful for a pointer to whatever I need to do to let the build system know that my files are utf8. Incidentally, it works fine if I build in Eclipse, but I need to build from the command line. Thanks!

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