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• Removing padding from structure in kernel module

  - by dexkid

  I am compiling a kernel module, containing a structure of size 34, using the standard command. make -C /lib/modules/$(KVERSION)/build M=$(PWD) modules The sizeof(some_structure) is coming as 36 instead of 34 i.e. the compiler is padding the structure. How do I remove this padding? Running make V=1 shows the gcc compiler options passed as make -I../inc -C /lib/modules/2.6.29.4-167.fc11.i686.PAE/build M=/home/vishal/20100426_eth_vishal/organised_eth/src modules make[1]: Entering directory `/usr/src/kernels/2.6.29.4-167.fc11.i686.PAE' test -e include/linux/autoconf.h -a -e include/config/auto.conf || ( \ echo; \ echo " ERROR: Kernel configuration is invalid."; \ echo " include/linux/autoconf.h or include/config/auto.conf are missing."; \ echo " Run 'make oldconfig && make prepare' on kernel src to fix it."; \ echo; \ /bin/false) mkdir -p /home/vishal/20100426_eth_vishal/organised_eth/src/.tmp_versions ; rm -f /home/vishal/20100426_eth_vishal/organised_eth/src/.tmp_versions/* make -f scripts/Makefile.build obj=/home/vishal/20100426_eth_vishal/organised_eth/src gcc -Wp,-MD,/home/vishal/20100426_eth_vishal/organised_eth/src/.eth_main.o.d -nostdinc -isystem /usr/lib/gcc/i586-redhat-linux/4.4.0/include -Iinclude -I/usr/src/kernels/2.6.29.4-167.fc11.i686.PAE/arch/x86/include -include include/linux/autoconf.h -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Os -m32 -msoft-float -mregparm=3 -freg-struct-return -mpreferred-stack-boundary=2 -march=i686 -mtune=generic -Wa,-mtune=generic32 -ffreestanding -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -Iarch/x86/include/asm/mach-generic -Iarch/x86/include/asm/mach-default -Wframe-larger-than=1024 -fno-stack-protector -fno-omit-frame-pointer -fno-optimize-sibling-calls -g -pg -Wdeclaration-after-statement -Wno-pointer-sign -fwrapv -fno-dwarf2-cfi-asm -DTX_DESCRIPTOR_IN_SYSTEM_MEMORY -DRX_DESCRIPTOR_IN_SYSTEM_MEMORY -DTX_BUFFER_IN_SYSTEM_MEMORY -DRX_BUFFER_IN_SYSTEM_MEMORY -DALTERNATE_DESCRIPTORS -DEXT_8_BYTE_DESCRIPTOR -O0 -Wall -DT_ETH_1588_051 -DALTERNATE_DESCRIPTORS -DEXT_8_BYTE_DESCRIPTOR -DNETHERNET_INTERRUPTS -DETH_IEEE1588_TESTS -DSNAPTYPSEL_TMSTRENA_TEVENTENA_TESTS -DT_ETH_1588_140_147 -DLOW_DEBUG_PRINTS -DMEDIUM_DEBUG_PRINTS -DHIGH_DEBUG_PRINTS -DMODULE -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(eth_main)" -D"KBUILD_MODNAME=KBUILD_STR(conxt_eth)" -c -o /home/vishal/20100426_eth_vishal/organised_eth/src/eth_main.o /home/vishal/20100426_eth_vishal/organised_eth/src/eth_main.c

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• Retrieve data from .dat file.

  - by Zach

  We have an application which requires us to read data from a file (.dat) dynamically using deserialization. We are actually getting first object and it throws null pointer exception when we are accessing other objects using a "for" loop. File file=null; FileOutputStream fos=null; BufferedOutputStream bos=null; ObjectOutputStream oos=null; try{ file=new File("account4.dat"); fos=new FileOutputStream(file,true); bos=new BufferedOutputStream(fos); oos=new ObjectOutputStream(bos); oos.writeObject(m); System.out.println("object serialized"); amlist=new MemberAccountList(); oos.close(); } catch(Exception ex){ ex.printStackTrace(); } Reading objects: try{ MemberAccount m1; file=new File("account4.dat");//add your code here fis=new FileInputStream(file); bis=new BufferedInputStream(fis); ois=new ObjectInputStream(bis); System.out.println(ois.readObject()); while(ois.readObject()!=null){ m1=(MemberAccount)ois.readObject(); System.out.println(m1.toString()); }/mList.addElement(m1); // Here we have the issue throwing null pointer exception Enumeration elist=mList.elements(); while(elist.hasMoreElements()){ obj=elist.nextElement(); System.out.println(obj.toString()); }/ } catch(ClassNotFoundException e){ } catch(EOFException e){ System.out.println("end"); } catch(Exception ex){ ex.printStackTrace(); }

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• Simulating pass by reference for an array in Java

  - by Leif Andersen

  I was wondering, in java, is it possible to in anyway, simulate pass by reference for an array? Yes, I know the language doesn't support it, but is there anyway I can do it. Say, for example, I want to create a method that reverses the order of all the elements in an array. (I know that this code snippet isn't the best example, as there is a better algorithms to do this, but this is a good example of the type of thing I want to do for more complex problems). Currently, I need to make a class like this: public static void reverse(Object[] arr) { Object[] tmpArr = new Object[arr.length]; count = arr.length - 1; for(Object i : arr) tmpArr[count--] = i; // I would like to do arr = tmpArr, but that will only make the shallow // reference tmpArr, I would like to actually change the pointer they passed in // Not just the values in the array, so I have to do this: count = arr.length - 1; for(Object i : tmpArr) arr[count--] = i; return; } Yes, I know that I could just swap the values until I get to the middle, and it would be much more efficient, but for other, more complex purposes, is there anyway that I can manipulate the actual pointer? Again, thank you.

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• Position an icon on the right in the middle of a list item

  - by Andy

  I have the following code which prints an img if the current page is selected. The issue i have is if the list item is a varied height i cant position it in the middle of the list item on the far right... <li><?php echo $child->link($child->title); ?><?php echo (url_start_with($child->url) ? '<img src="images/ico-arrow.png" class="pointer">': null); ?></li> how can i ammend the "TOP" so that it will position itself vertically no matter what the height using css #bf-fest-list li { margin:0; padding:5px 25px; position:relative; } #bf-fest-list li a:hover { color:#ec1c23; text-decoration:none; } #bf-fest-list li.current { background:#a0a1a4; padding:10px 25px; } #bf-fest-list li.current a { color:#FFF; } #bf-fest-list li .pointer { position:absolute; top:10px; left:233px; }

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• Simulating pass by reference for an array reference (i.e. a reference to a reference) in Java

  - by Leif Andersen

  I was wondering, in java, is it possible to in anyway, simulate pass by reference for an array? Yes, I know the language doesn't support it, but is there anyway I can do it. Say, for example, I want to create a method that reverses the order of all the elements in an array. (I know that this code snippet isn't the best example, as there is a better algorithms to do this, but this is a good example of the type of thing I want to do for more complex problems). Currently, I need to make a class like this: public static void reverse(Object[] arr) { Object[] tmpArr = new Object[arr.length]; count = arr.length - 1; for(Object i : arr) tmpArr[count--] = i; // I would like to do arr = tmpArr, but that will only make the shallow // reference tmpArr, I would like to actually change the pointer they passed in // Not just the values in the array, so I have to do this: count = arr.length - 1; for(Object i : tmpArr) arr[count--] = i; return; } Yes, I know that I could just swap the values until I get to the middle, and it would be much more efficient, but for other, more complex purposes, is there anyway that I can manipulate the actual pointer? Again, thank you.

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• Where my memory is alloced, Stack or Heap, Can I find it at Run-time?

  - by AKN

  I know that memory alloced using new, gets its space in heap, and so we need to delete it before program ends, to avoid memory leak. Let's look at this program... Case 1: char *MyData = new char[20]; _tcscpy(MyData,"Value"); . . . delete[] MyData; MyData = NULL; Case 2: char *MyData = new char[20]; MyData = "Value"; . . . delete[] MyData; MyData = NULL; In case 2, instead of allocating value to the heap memory, it is pointing to a string literal. Now when we do a delete it would crash, AS EXPECTED, since it is not trying to delete a heap memory. Is there a way to know where the pointer is pointing to heap or stack? By this the programmer Will not try to delete any stack memory He can investigate why does this ponter, that was pointing to a heap memory initially, is made to refer local literals? What happened to the heap memory in the middle? Is it being made to point by another pointer and delete elsewhere and all that?

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• Opacity CSS not working in IE8

  - by Alistair Christie

  I'm using CSS to indicate the trigger text for a jQuery slide-down section: i.e. when you hover over the trigger text the cursor changes to a pointer and the opacity of the trigger text is reduced to indicate that the text has a click action. This works fine in Firefox and Chrome, but in IE8 the opacity doesn't change. I've tried a variety of CSS settings without any success. For example HTML: <h3 class="slidedownTrigger">This is the trigger text</h3> CSS: .slidedownTrigger {     cursor: pointer;     -ms-filter: “progid:DXImageTransform.Microsoft.Alpha(Opacity=75)”;     filter: alpha(opacity=75);     -khtml-opacity: 0.75;     -moz-opacity: 0.75;     opacity: 0.75; } What's stopping IE changing the opacity? Note: I've tried this on a variety of different elements, swapping round the order of the CSS statements, and just using the IE ones on their own. I've also tried using -ms-filter: "alpha(opacity=75)"; but with no success. I've run out of things to try to get opacity modification working in IE8. Any ideas?

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• Save QList<int> to QSettings

  - by Tobias

  Hello, I want to save a QList<int> to my QSettings without looping through it. I know that I could use writeArray() and a loop to save all items or to write the QList to a QByteArray and save this but then it is not human readable in my INI file.. Currently I am using the following to transform my QList<int> to QList<QVariant>: QList<QVariant> variantList; //Temp is the QList<int> for (int i = 0; i < temp.size(); i++) variantList.append(temp.at(i)); And to save this QList<Variant> to my Settings I use the following code: QVariant list; list.setValue(variantList); //saveSession is my QSettings object saveSession.setValue("MyList", list); The QList is correctly saved to my INI file as I can see (comma seperated list of my ints) But the function crashes on exit. I already tried to use a pointer to my QSettings object instead but then it crashes on deleting the pointer ..

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• C function const multidimensional-array argument strange warning

  - by rogi

  Ehllo, I'm getting some strange warning about this code: typedef double mat4[4][4]; void mprod4(mat4 r, const mat4 a, const mat4 b) { /* yes, function is empty */ } int main() { mat4 mr, ma, mb; mprod4(mr, ma, mb); } gcc output as follows: $ gcc -o test test.c test.c: In function 'main': test.c:13: warning: passing argument 2 of 'mprod4' from incompatible pointer type test.c:4: note: expected 'const double (*)[4]' but argument is of type 'double (*)[4]' test.c:13: warning: passing argument 3 of 'mprod4' from incompatible pointer type test.c:4: note: expected 'const double ()[4]' but argument is of type 'double ()[4]' defining the function as: void mprod4(mat4 r, mat4 a, mat4 b) { } OR defining matrices at main as: mat4 mr; const mat4 ma; const mat4 mb; OR calling teh function in main as: mprod4(mr, (const double(*)[4])ma, (const double(*)[4])mb); OR even defining mat4 as: typedef double mat4[16]; make teh warning go away. Wat is happening here? Am I doing something invalid? gcc version is 4.4.3 if relevant. Thanks for your attention.

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• sIFR - getting a:hover to work in navigation list

  - by HudRom

  Hi, I am currently struggling with sIFR and a:hover. My problem site is hosted at http://irene.huditsch.info I have the following HTML code: <body id="irene-huditsch-info"> <div id="header"> <h1>Irene Huditsch</h1> <div id="top-nav"> <ul> <li id="impressum"> <a href="impressum.html" rel="index">Impressum</a> </li> <li id="kontakt"> <a href="kontakt.html">Kontakt</a> </li> </ul> </div> ... My sIFR-config.js looks like: sIFR.replace(braganza, { selector: 'div#top-nav a', css: '.sIFR-root { background-color: transparent; color: #FFFFFF; line-height: 13px; font-size: 11px; text-decoration: underline; cursor: pointer; } .sIFR-root:hover { color: #592b02; }', wmode: 'transparent' }); But the hover doesn't take effect. I tried different solution with no success either. When I write sIFR.replace(braganza, { selector: 'div#top-nav li', css: 'a { background-color: transparent; color: #FFFFFF; line-height: 13px; font-size: 11px; text-decoration: underline; cursor: pointer; } a:hover { color: #592b02; }', wmode: 'transparent' }); (which seems logical to me), the list items are not rendered at all. Could you please give me an advice how to do it correctly with the structure given? Thanks, Roman

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• Declaration of arrays before "normal" variables in c?

  - by bjarkef

  Hi We are currently developing an application for a msp430 MCU, and are running into some weird problems. We discovered that declaring arrays withing a scope after declaration of "normal" variables, sometimes causes what seems to be undefined behavior. Like this: foo(int a, int *b); int main(void) { int x = 2; int arr[5]; foo(x, arr); return 0; } foo sometimes is passed a pointer as the second variable, that does not point to the arr array. We verify this by single stepping through the program, and see that the value of the arr variable in the main scope is not the same as the value of the b pointer variable in the foo scope. And no, this is not really reproduceable, we have just observed this behavior once in a while. Changing the example seems to solve the problem, like this: foo(int a, int *b); int main(void) { int arr[5]; int x = 2; foo(x, arr); return 0; } Does anybody have any input or hints as to why we experience this behavior? Or similar experiences? The MSP430 programming guide specifies that code should conform to the ANSI C89 spec. and so I was wondering if it says that arrays has to be declared before non-array variables? Any input on this would be appreciated.

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• Finding a 3rd party QWidget with injected code & QWidget::find(hwnd)

  - by David Menard

  Hey, I have a Qt Dll wich I inject into a third-party Application using windows detours library: if(!DetourCreateProcessWithDll( Path, NULL, NULL, NULL, TRUE, CREATE_DEFAULT_ERROR_MODE | CREATE_SUSPENDED, NULL, NULL, &si, &pi, "C:\\Program Files\\Microsoft Research\\Detours Express 2.1\\bin\\detoured.dll", "C:\\Users\\Dave\\Documents\\Visual Studio 2008\\Projects\\XOR\\Debug\\XOR.dll", NULL)) and then I set a system-wide hook to intercept window creation: HHOOK h_hook = ::SetWindowsHookEx(WH_CBT, (HOOKPROC)CBTProc, Status::getInstance()->getXORInstance(), 0); Where XOR is my programs name, and Status::getInstance() is a Singleton where I keep globals. In my CBTProc callback, I want to intercept all windows that are QWidgets: HWND hwnd= FindWindow(L"QWidget", NULL); which works well, since I get a corresponding HWND (I checked with Spy++) Then, I want to get a pointer to the QWidget, so I can use its functions: QWidget* q = QWidget::find(hwnd); but here's the problem, the returned pointer is always 0. Am I not injecting my code into the process properly? Or am I not using QWidget::find() as I should? Thanks, Dave EDIT:If i change the QWidget::find() function to an exported function of my DLL, after setting the hooks (so I can set and catch a breakpoint), QWidgetPrivate::mapper is NULL.

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• Printing an invisible NSView

  - by Rodger Wilson

  Initially I created a simple program with a custom NSView. I drew a picture (certificate) and printed it! beautiful! Everything worked great! I them moved my custom NSView to an existing application. My hope was that when a user hit print it would print this certificate. Simple enough. I figured a could have a NSView pointer in my controller code. Then at initialization I would populate the pointer. Then when someone wanted to print the certificate it would print. The problem is that all of my drawing code is in the "drawRect" method. This method doesn't get called because this view is never displayed in a window. I have heart that others use non-visible NSView objects just for printing. What do I need to do. I really don't want to show this view to the screen. Rodger

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• A queue in C using structs and dynamic memory allocation (linked list)

  - by Martin Pugh

  I am tasked with making a queue data structure in C, as a linked list. Our lecturer gave us a large amount of code to implement a stack, but we have to adapt it to create a queue. The code our lecturer gave us ends up not compiling and segfaulting at the exact same point as the code I wrote for the queue. I'm very new to structs, malloc and C in general, so there could be something painfully obvious I've overlooked. Here is the code I am using: #include <stdio.h> #include <stdlib.h> struct node{ int data; //contains the actual data struct node *prev; //pointer to previous node (Closer to front) struct node *next; //pointer to next node (Closer to back) }; typedef struct node *Nodepointer; struct queue{ Nodepointer front; Nodepointer back; }; typedef struct queue *Queuepointer; main(){ Queuepointer myqueue; //create a queue called myqueue init(myqueue); //initialise the queue Nodepointer new = (Nodepointer)malloc(sizeof(struct node)); myqueue->front = new; } int init(Queuepointer q){ q = (Queuepointer)malloc(sizeof(struct queue)); q->front = NULL; q->back = NULL; } The idea is that the queue struct 'contains' the first and last nodes in a queue, and when a node is created, myqueue is updated. However, I cannot even get to that part (pop and push are written but omitted for brevity). The code is segfaulting at the line myqueue->front = new; with the following gdb output: Program received signal SIGSEGV, Segmentation fault. 0x08048401 in main () at queue.c:27 27 myqueue->front = new; Any idea what I'm doing wrong?

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• array of structs in C

  - by Hristo

  I'm trying to create an array of structs and also a pointer to that array. I don't know how large the array is going to be, so it should be dynamic. My struct would look something like this: typedef struct _stats_t { int hours[24]; int numPostsInHour; int days[7]; int numPostsInDay; int weeks[20]; int numPostsInWeek; int totNumLinesInPosts; int numPostsAnalyzed; } stats_t; ... and I need to have multiple of these structs for each file (unknown amount) that I will analyze. I'm not sure how to do this. I don't like the following approach because of the limit of the size of the array: # define MAX 10 typedef struct _stats_t { int hours[24]; int numPostsInHour; int days[7]; int numPostsInDay; int weeks[20]; int numPostsInWeek; int totNumLinesInPosts; int numPostsAnalyzed; } stats_t[MAX]; So how would I create this array? Also, would a pointer to this array would look something this? stats_t stats[]; stats_t *statsPtr = &stats[0]; Thanks, Hristo

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• Microsoft Detours - DetourUpdateThread?

  - by pault543

  Hi, I have a few quick questions about the Microsoft Detours Library. I have used it before (successfully), but I just had a thought about this function: LONG DetourUpdateThread(HANDLE hThread); I read elsewhere that this function will actually suspend the thread until the transaction completes. This seems odd since most sample code calls: DetourUpdateThread(GetCurrentThread()); Anyway, apparently this function "enlists" threads so that, when the transaction commits (and the detours are made), their instruction pointers are modified if they lie "within the rewritten code in either the target function or the trampoline function." My questions are: When the transaction commits, is the current thread's instruction pointer going to be within the DetourTransactionCommit function? If so, why should we bother enlisting it to be updated? Also, if the enlisted threads are suspended, how can the current thread continue executing (given that most sample code calls DetourUpdateThread(GetCurrentThread());)? Finally, could you suspend all threads for the current process, avoiding race conditions (considering that threads could be getting created and destroyed at any time)? Perhaps this is done when the transaction begins? This would allow us to enumerate threads more safely (as it seems less likely that new threads could be created), although what about CreateRemoteThread()? Thanks, Paul For reference, here is an extract from the simple sample: // DllMain function attaches and detaches the TimedSleep detour to the // Sleep target function. The Sleep target function is referred to // through the TrueSleep target pointer. BOOL WINAPI DllMain(HINSTANCE hinst, DWORD dwReason, LPVOID reserved) { if (dwReason == DLL_PROCESS_ATTACH) { DetourTransactionBegin(); DetourUpdateThread(GetCurrentThread()); DetourAttach(&(PVOID&)TrueSleep, TimedSleep); DetourTransactionCommit(); } else if (dwReason == DLL_PROCESS_DETACH) { DetourTransactionBegin(); DetourUpdateThread(GetCurrentThread()); DetourDetach(&(PVOID&)TrueSleep, TimedSleep); DetourTransactionCommit(); } return TRUE; }

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• How can I change the text in a <span></span> element using jQuery?

  - by Eric Reynolds

  I have a span element as follows: <span id="download">Download</span>. This element is controlled by a few radio buttons. Basically, what I want to do is have 1 button to download the item selected by the radio buttons, but am looking to make it a little more "flashy" by changing the text inside the <span> to say more specifically what they are downloading. The span is the downloading button, and I have it animated so that the span calls slideUp(), then should change the text, then return by slideDown().Here is the code I am using that does not want to work. $("input[name=method]").change(function() { if($("input[name=method]").val() == 'installer') { $('#download').slideUp(500); $('#download').removeClass("downloadRequest").removeClass("styling").css({"cursor":"default"}); $('#download').text("Download"); $('#download').addClass("downloadRequest").addClass("styling").css({"cursor":"pointer"}); $('#download').slideDown(500); } else if($("input[name=method]").val() == 'url') { $('#download').slideUp(500); $('#download').removeClass("downloadRequest").removeClass("styling").css({"cursor":"default"}); $('#download').text("Download From Vendor Website"); $('#download').addClass("styling").addClass("downloadRequest").css({"cursor":"pointer"}); $('#download').slideDown(500); } }); I changed the code a bit to be more readable so I know that it doesn't have the short code that jQuery so eloquently allows. Everything in the code works, with the exception of the changing of the text inside the span. I'm sure its a simple solution that I am just overlooking. Any help is appreciated, Eric R.

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• Strcpy and malloc issues

  - by mrblippy

  Hi, i am having trouble getting a method relating to a linked list working, i get the errors: assignment makes pointer from integer without a cast and passing argument 1 of âstrcpyâ makes pointer from integer without a cast. i have tried to include all the relevant code, but let me know if you need more info. thanks. struct unit { char code[5]; char *name; node_ptr students; }; typedef struct node *node_ptr; struct node { int student_id; char *studentname; node_ptr next; }; void enrol_student(struct unit u[], int n) { int i, p; int student_id = 0; char code_to_enrol[7]; char buffer[100]; node_ptr studentslist; scanf("%s\n", code_to_enrol); for(i=0; i <= n; i++) { studentslist = u[i].students; if(strcmp(u[i].code ,code_to_enrol)<=0) { scanf("enter student details %d %s\n", &studentID, buffer); p = (char *) malloc (strlen(buffer)+1); strcpy(p, buffer); insert_in_order(student_id, buffer, studentslist); } } } void insert_in_order(int n, char *i, node_ptr list) { node_ptr before = list; node_ptr students = (node_ptr) malloc(sizeof(struct node)); students->ID = n; students->name = *i; while(before->next && (before->next->ID < n)) { before = before->next; } students->next = before->next; before->next = students; }

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• Boost::Mutex & Malloc

  - by M. Tibbits

  Hi all, I'm trying to use a faster memory allocator in C++. I can't use Hoard due to licensing / cost. I was using NEDMalloc in a single threaded setting and got excellent performance, but I'm wondering if I should switch to something else -- as I understand things, NEDMalloc is just a replacement for C-based malloc() & free(), not the C++-based new & delete operators (which I use extensively). The problem is that I now need to be thread-safe, so I'm trying to malloc an object which is reference counted (to prevent excess copying), but which also contains a mutex pointer. That way, if you're about to delete the last copy, you first need to lock the pointer, then free the object, and lastly unlock & free the mutex. However, using malloc to create a boost::mutex appears impossible because I can't initialize the private object as calling the constructor directly ist verboten. So I'm left with this odd situation, where I'm using new to allocate the lock and nedmalloc to allocate everything else. But when I allocate a large amount of memory, I run into allocation errors (which disappear when I switch to malloc instead of nedmalloc ~ but the performance is terrible). My guess is that this is due to fragmentation in the memory and an inability of nedmalloc and new to place nice side by side. There has to be a better solution. What would you suggest?

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• Passing arguments to objects created using the new operator?

  - by Abhijit

  Hi guys, I have a small C++ problem to which I don't know the best solution. I have two classes A and B as follows: class A { int n; B* b; public: A(int num): n(num) { b = new B[n]; for (int i = 0; i < n; i++) { b[i].setRef(this); } } ~A() { delete [] b; } }; class B { A* a; public: B() { } B(A* aref) { a = aref; } void setRef(A* aref) { a = aref; } }; I am creating an object of class A by passing to its constructor the number of objects of class B I want to be created. I want every object of class B to hold a pointer to the class A object that creates it. I think the best way to do this would be by passing the pointer to the class A object as a constructor argument to the class B object. However, since I'm using the new operator, the no-args constructor for class B is called. As a result, the only solution I can see here is calling the setRef(A*) method for every object of class B after it has been constructed using the new operator. Is there a better solution/design pattern that would be more applicable here? Would using placement new for class B be a better solution? Thanks in advance for your help.

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• C# override WndProc in Control level to detect

  - by Nullstr1ng

  I have overridden WndProc in UserControl level to detect MouseDown, MouseUp, and MouseMove to any Control added in that UserControl. protected override void WndProc(ref Message m) { Point mouseLoc = new Point(); switch (m.Msg) { case WM_LBUTTONDOWN: System.Diagnostics.Debug.WriteLine("mouse down"); //this.OnMouseDown(new MouseEventArgs(MouseButtons.Left, 1, mouseLoc.X, mouseLoc.Y, 0)); break; case WM_LBUTTONUP: System.Diagnostics.Debug.WriteLine("mouse up"); //this.OnMouseDown(new MouseEventArgs(MouseButtons.Left, 1, mouseLoc.X,mouseLoc.Y, 0)); break; case WM_MOUSEMOVE: int lParam = m.LParam.ToInt32(); //mouseLoc.X = lParam & 0xFFFF; //mouseLoc.Y = (int)(lParam & 0xFFFF0000 >> 16); mouseLoc.X = (Int16)m.LParam; mouseLoc.Y = (Int16)((int)m.LParam >> 16); System.Diagnostics.Debug.WriteLine("mouse move: " + mouseLoc.X + ", " + mouseLoc.Y); //this.OnMouseDown(new MouseEventArgs(MouseButtons.Left, 1, mouseLoc.X,mouseLoc.Y, 0)); break; } base.WndProc(ref m); } MouseMove, Down, and Up are working when the mouse pointer is in UserControl but when the mouse pointer is on other control (inside my UserControl) it doesn't work. Am I doing something wrong? Currently developing a flick and scroll control.

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• Choosing circle radius to fully fill a rectangle

  - by Andy

  Hi, the pixman image library can draw radial color gradients between two circles. I'd like the radial gradient to fill a rectangular area defined by "width" and "height" completely. Now my question, how should I choose the radius of the outer circle? My current parameters are the following: A) inner circle (start of gradient) center pointer of inner circle: (width*0.5|height*0.5) radius of inner circle: 1 color: black B) outer circle (end of gradient) center pointer of outer circle: (width*0.5|height*0.5) radius of outer circle: ??? color: white How should I choose the radius of the outer circle to make sure that the outer circle will entirely fill my bounding rectangle defined by width*height. There shall be no empty areas in the corners, the area shall be completely covered by the circle. In other words, the bounding rectangle width,height must fit entirely into the outer circle. Choosing outer_radius = max(width, height) * 0.5 as the radius for the outer circle is obviously not enough. It must be bigger, but how much bigger? Thanks!

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• Android app after update: crashes on Motorola Cliq with weird stacktrace

  - by sandis

  So after updating my app on the market I am getting reports from motorola cliq-users that my app crashes on start. The stacktrace is below, and is not very helpful since it does not go trough my app! Unfortunately I have no access to a motorola cliq-phone by myself, and I have changed too many things in this update to know what is causing the trouble. Have anyone of you guys run into the same problem? I would very much appreciate help with this problem! 05-26 11:44:06.521 I/PacketReader( 116): Got the features element 05-26 11:44:06.941 W/WindowManager( 86): No window to dispatch pointer action 0 05-26 11:44:07.381 W/WindowManager( 86): No window to dispatch pointer action 1 05-26 11:44:07.691 W/ActivityManager( 86): Launch timeout has expired, giving up wake lock! 05-26 11:44:07.931 W/ActivityManager( 86): Activity idle timeout for HistoryRecord{43714db8 {my.package/my.package.Main}} 05-26 11:44:08.531 E/AndroidRuntime( 565): Uncaught handler: thread main exiting due to uncaught exception 05-26 11:44:08.541 E/AndroidRuntime( 565): java.lang.RuntimeException: Unable to start activity ComponentInfo{my.packageC/my.package.Main}: java.lang.NullPointerException 05-26 11:44:08.541 E/AndroidRuntime( 565): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2297) 05-26 11:44:08.541 E/AndroidRuntime( 565): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2313) 05-26 11:44:08.541 E/AndroidRuntime( 565): at android.app.ActivityThread.access$2000(ActivityThread.java:115) 05-26 11:44:08.541 E/AndroidRuntime( 565): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1721) 05-26 11:44:08.541 E/AndroidRuntime( 565): at android.os.Handler.dispatchMessage(Handler.java:99) 05-26 11:44:08.541 E/AndroidRuntime( 565): at android.os.Looper.loop(Looper.java:123) 05-26 11:44:08.541 E/AndroidRuntime( 565): at android.app.ActivityThread.main(ActivityThread.java:3977) 05-26 11:44:08.541 E/AndroidRuntime( 565): at java.lang.reflect.Method.invokeNative(Native Method) 05-26 11:44:08.541 E/AndroidRuntime( 565): at java.lang.reflect.Method.invoke(Method.java:521) 05-26 11:44:08.541 E/AndroidRuntime( 565): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782) 05-26 11:44:08.541 E/AndroidRuntime( 565): at com.android.internal.os.ZygoteI

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• Strange XCode debugger behavior with UITableView datasource

  - by Tarfa

  Hey guys. I've got a perplexing issue. In my subclassed UITableViewController my datasource methods lose their tableview reference depending on lines of code I put inside the method. For example, in this code block: - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { // Return the number of sections. return 3; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { // Return the number of rows in the section. return 5; } // Customize the appearance of table view cells. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { id i = tableView; static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } // Configure the cell... return cell; } the "id i = tableView;" causes the tableview to become nil (0x0) -- and it causes it to be nil before I ever start stepping into the method. If I insert an assignment statement above the "id i = tableview;" statement: CGFloat x = 5.0; id i = tableView; then tableview retains its pointer (i.e. is not nil) if I place the breakpoint after the "id i = tableView;" line. In other words, the breakpoint must be set after the "id i = tableView"; assignment in order for tableView to retain its pointer. If the breakpoint is set before the assignment is made and I just hang at that breakpoint for a bit then after a couple of seconds the console logs this error message: Assertion failed: (cls), function getName, file /SourceCache/objc4_Sim/objc4-427.5/runtime/objc-runtime-new.mm, line 3990. Although the code works when I don't step through the method, I need my debugger to work! It makes programming kind of challenging when your debugging tools become your enemy. Anyone know what the cause and solution are? Thanks.

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• What do I name this class whose sole purpose is to report failure?

  - by Blair Holloway

  In our system, we have a number of classes whose construction must happen asynchronously. We wrap the construction process in another class that derives from an IConstructor class: class IConstructor { public: virtual void Update() = 0; virtual Status GetStatus() = 0; virtual int GetLastError() = 0; }; There's an issue with the design of the current system - the functions that create the IConstructor-derived classes are often doing additional work which can also fail. At that point, instead of getting a constructor which can be queried for an error, a NULL pointer is returned. Restructuring the code to avoid this is possible, but time-consuming. In the meantime, I decided to create a constructor class which we create and return in case of error, instead of a NULL pointer: class FailedConstructor : public IConstructor public: virtual void Update() {} virtual Status GetStatus() { return STATUS_ERROR; } virtual int GetLastError() { return m_errorCode; } private: int m_errorCode; }; All of the above this the setup for a mundane question: what do I name the FailedConstructor class? In our current system, FailedConstructor would indicate "a class which constructs an instance of Failed", not "a class which represents a failed attempt to construct another class". I feel like it should be named for one of the design patterns, like Proxy or Adapter, but I'm not sure which.

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