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  • WebKit and npapi and mingw-w64

    - by rubenvb
    Hi, The problem is the following: On Windows x64, pointers are 64-bit, but type long is 32-bit. MSVC doesn't seem to care, and even omits warnings about pointer truncation on the default warning level. Since recently, there is a GCC that target x86_64-w64-mingw32, or better Windows x64 native. GCC produces errors when pointers are truncated (which is the logical thing to do...), and this is causing trouble in WebKit and more specifically, the Netscape Plugin API: First, there's the files (I can only post one hyperlink...): http://trac.webkit.org/browser/trunk/WebCore/ bridge/npapi.h -- defines uint32 as 32-bit int type (~line 145) plugins/win/PluginViewWin.cpp -- casts Windows window handles to 32-bit int, truncating them (~line 450) My proposed fix was to change the uint32 casts to uintptr_t, which makes GCC happy, but still puts a 64-bit value in a uint32 (=unsigned long). I have no clue how to solve this, because clearly WebKit is happy truncating pointers on Win64... How can I solve this the right way? Thanks!

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  • Alternative to c++ static virtual methods

    - by Jaime Pardos
    In C++ is not possible to declare a static virtual function, neither cast a non-static function to a C style function pointer. Now, I have a plain ol' C SDK that uses function pointers heavily. I have to fill a structure with several function pointers. I was planning to use an abstract class with a bunch of static pure virtual methods, and redefine them in derived classes and fill the structure with them. It wasn't until then that I realized that static virtual are not allowed in C++. Is there any good alternative? The best I can think of is defining some pure virtual methods GetFuncA(), GetFuncB(),... and some static members FuncA()/FuncB() in each derived class, which would be returned by the GetFuncX(). Then a function in the abstract class would call those functions to get the pointers and fill the structure.

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  • C++ Pointer member function with templates assignment with a member function of another class

    - by Agusti
    Hi, I have this class: class IShaderParam{ public: std::string name_value; }; template<class TParam> class TShaderParam:public IShaderParam{ public: void (TShaderParam::*send_to_shader)( const TParam&,const std::string&); TShaderParam():send_to_shader(NULL){} TParam value; void up_to_shader(); }; typedef TShaderParam<float> FloatShaderParam; typedef TShaderParam<D3DXVECTOR3> Vec3ShaderParam; In another class, I have a vector of IShaderParams* and functions that i want to send to "send_to_shader". I'm trying assign the reference of these functions like this: Vec3ShaderParam *_param = new Vec3ShaderParam; _param-send_to_shader = &TShader::setVector3; This is the function: void TShader::setVector3(const D3DXVECTOR3 &vec, const std::string &name){ //... } And this is the class with IshaderParams*: class TShader{ std::vector params; public: Shader effect; std::string technique_name; TShader(std::string& afilename):effect(NULL){}; ~TShader(); void setVector3(const D3DXVECTOR3 &vec, const std::string &name); When I compile the project with Visual Studio C++ Express 2008 I recieve this error: Error 2 error C2440: '=' :can't make the conversion 'void (__thiscall TShader::* )(const D3DXVECTOR3 &,const std::string &)' a 'void (__thiscall TShaderParam::* )(const TParam &,const std::string &)' c:\users\isagoras\documents\mcv\afoc\shader.cpp 127 Can I do the assignment? No? I don't know how :-S Yes, I know that I can achieve the same objective with other techniques, but I want to know how can I do this..

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  • pointer to a pointer in a linked list

    - by user1596497
    I'm trying to set a linked list head through pointer to a pointer. I can see inside the function that the address of the head pointer is changing but as i return to the main progran it becomes NULL again. can someone tell me what I'm doing wrong ?? #include <stdio.h> #include <stdlib.h> typedef void(*fun_t)(int); typedef struct timer_t { int time; fun_t func; struct timer_t *next; }TIMER_T; void add_timer(int sec, fun_t func, TIMER_T *head); void run_timers(TIMER_T **head); void timer_func(int); int main(void) { TIMER_T *head = NULL; int time = 1; fun_t func = timer_func; while (time < 1000) { printf("\nCalling add_timer(time=%d, func=0x%x, head=0x%x)\n", time, func, &head); add_timer(time, func, head); time *= 2; } run_timers(&head); return 0; } void add_timer(int sec, fun_t func, TIMER_T *head) { TIMER_T ** ppScan=&head; TIMER_T *new_timer = NULL; new_timer = (TIMER_T*)malloc(sizeof(TIMER_T)); new_timer->time = sec; new_timer->func = func; new_timer->next = NULL; while((*ppScan != NULL) && (((**ppScan).time)<sec)) ppScan = &(*ppScan)->next; new_timer->next = *ppScan; *ppScan = new_timer; }

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  • Consumed WCF service returns void although return type (& value) specified

    - by Abs
    I have a WCF service that I am attempting to connect to via a console application for testing (although will move to WPF for the final interface). I have generated the proxy, added the service reference to my project in visual studio and I can see all the methods I have created in my WCF interface: SupportStaffServiceClient client = new SupportStaffServiceClient("WSHttpBinding_ISupportStaffService"); client.myMethod(message); However when I call a method, which in the WCF interface is specified as returning a value, the method returns void in the console application. client.getMethod(message); The WCF service method is definitely returning a message, I'm just unsure as to why the client cannot "see" the return.

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  • Memory leak using (void) alloc

    - by Rudiger
    I have seen a similar line of code floating about in Apples code: (void)[[URLRequest alloc] initializeRequestWithValues:postBody url:verifySession httpHeader:nil delegate:self]; URLRequest is my own custom class. I didn't write this and I think the guy that did just grabbed it from Apple's example. To me this should leak and when I test it I'm pretty sure it leaks 16 bytes. Would it? I know how to fix it if it does but wasn't sure as it was taken from Apple's code.

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  • java.lang.Void in C#?

    - by user313661
    Hi, I am currently working with .Net 2.0 and have an interface whose generic type is used to define a method's return type. Something like interface IExecutor<T> { T Execute() { ... } } My problem is that some classes that implement this interface do not really need to return anything. In Java you can use java.lang.Void for this purpose, but after quite a bit of searching I found no equivalent in C#. More generically, I also did not find a good way around this problem. I tried to find how people would do this with delegates, but found nothing either - which makes me believe that the problem is that I suck at searching :) So what's the best way to solve this? How would you do it? Thanks!

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  • Convert void* representation of a dword to wstring

    - by graham.reeds
    I am having dumb monday so my apologies for posting such a newbie-like question. I am using CRegKey.QueryValue to return a dword value from the registry. QueryValue writes the value into void* pData and the length into ULONG* pnBytes. Now there is a way of getting it from pData into a wstring probably via stringstream. The closest I came was getting the result as a hex string. I was about to work on converting the hex representation to a dword and then from there to a wstring when I decided that was just dumb and ask on here instead of wasting another hour of my life on the problem.

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  • NSView -(void)keyDown in console program

    - by Jonas Byström
    I'm not getting the -(void)keyDown callback on my inherited NSOpenGLView (note that mouseMoved does not work either though I do setAcceptsMouseMovedEvents:YES, but that is not an issue yet). It implements - (BOOL)acceptsFirstResponder { return YES; } but still no luck. My knowledgeable friend implied that it might have something to do with that the application is still a console application and not a bundled .app (I'm currently porting it). If so: is there some way to circumvent? Could the cause be something else? When I terminate my console application, I frequently see all my keypresses go to stdout so it does seem reasonable...

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  • Java: Can't implement runnable on a test case: void run() collides

    - by Zombies
    So I have a test case that I want to make into a thread. I cannot extend Thread nor can I implement runnable since TestCase already has a method void run(). The compilation error I am getting is Error(62,17): method run() in class com.util.SeleneseTestCase cannot override method run() in class junit.framework.TestCase with different return type, was class junit.framework.TestResult. What I am trying to do is to scale a Selenium testcase up to perform stress testing. I am not able to use selenium grid/pushtotest.com/amazon cloud at this time (installation issues/install time/resource issues). So this really is more of a Java language issue for me.

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  • Warning of "Control may reach end of non-void function"

    - by Cloud_cal
    I ran a C++ program in Xcode, and encountered a warning of "Control may reach end of non-void function". Here is the code: Node* search(Node* head, int x) { if(!head) return NULL; else if(x == head->key) return head; else if(x < head->key) search(head->lchild, x); else search(head->rchild, x); } I got the same warning when compiling it in Linux, but got the correct result. But in Xcode, the result was wrong. By the way, I got the correct answer and no warning in Visual Studio.

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  • qsort on an array of pointers to Objective-C objects

    - by ElBueno
    I have an array of pointers to Objective-C objects. These objects have a sort key associated with them. I'm trying to use qsort to sort the array of pointers to these objects. However, the first time my comparator is called, the first argument points to the first element in my array, but the second argument points to garbage, giving me an EXC_BAD_ACCESS when I try to access its sort key. Here is my code (paraphrased): - (void)foo:(int)numThingies { Thingie **array; array = malloc(sizeof(deck[0])*numThingies); for(int i = 0; i < numThingies; i++) { array[i] = [[Thingie alloc] initWithSortKey:(float)random()/RAND_MAX]; } qsort(array[0], numThingies, sizeof(array[0]), thingieCmp); } int thingieCmp(const void *a, const void *b) { const Thingie *ia = (const Thingie *)a; const Thingie *ib = (const Thingie *)b; if (ia.sortKey > ib.sortKey) return 1; //ib point to garbage, so ib.sortKey produces the EXC_BAD_ACCESS else return -1; } Any ideas why this is happening?

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  • [Ruby] Object assignment and pointers

    - by Jergason
    I am a little confused about object assignment and pointers in Ruby, and coded up this snippet to test my assumptions. class Foo attr_accessor :one, :two def initialize(one, two) @one = one @two = two end end bar = Foo.new(1, 2) beans = bar puts bar puts beans beans.one = 2 puts bar puts beans puts beans.one puts bar.one I had assumed that when I assigned bar to beans, it would create a copy of the object, and modifying one would not affect the other. Alas, the output shows otherwise. ^_^[jergason:~]$ ruby test.rb #<Foo:0x100155c60> #<Foo:0x100155c60> #<Foo:0x100155c60> #<Foo:0x100155c60> 2 2 I believe that the numbers have something to do with the address of the object, and they are the same for both beans and bar, and when I modify beans, bar gets changed as well, which is not what I had expected. It appears that I am only creating a pointer to the object, not a copy of it. What do I need to do to copy the object on assignment, instead of creating a pointer? Tests with the Array class shows some strange behavior as well. foo = [0, 1, 2, 3, 4, 5] baz = foo puts "foo is #{foo}" puts "baz is #{baz}" foo.pop puts "foo is #{foo}" puts "baz is #{baz}" foo += ["a hill of beans is a wonderful thing"] puts "foo is #{foo}" puts "baz is #{baz}" This produces the following wonky output: foo is 012345 baz is 012345 foo is 01234 baz is 01234 foo is 01234a hill of beans is a wonderful thing baz is 01234 This blows my mind. Calling pop on foo affects baz as well, so it isn't a copy, but concatenating something onto foo only affects foo, and not baz. So when am I dealing with the original object, and when am I dealing with a copy? In my own classes, how can I make sure that assignment copies, and doesn't make pointers? Help this confused guy out.

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  • Confusion about pointers and their memory addresses

    - by TimothyTech
    alright, im looking at a code here and the idea is difficult to understand. #include <iostream> using namespace std; class Point { public : int X,Y; Point() : X(0), Y(0) {} }; void MoveUp (Point * p) { p -> Y += 5; } int main() { Point point MoveUp(&point) cout <<point.X << point.Y; return 0; } Alright, so i believe that a class is created and X and Y are declared and they are put inside a constructor a method is created and the argument is Point * p, which means that we are going to stick the constructor's pointer inside the function; now we create an object called point then call our method and put the pointers address inside it? isnt the pointers address just a memory number like 0x255255? and why wasnt p ever declared? (int * p = Y) what is a memory addres exactly? that it can be used as an argument?

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  • Sorting a Singly Linked List With Pointers

    - by Mark Simson
    I am trying to sort a singly linked list using bubble sort by manipulating ONLY the pointers, no keys. The following gets stuck in the for loop and loops infinitely. I don't understand why this is. Can anybody explain to me why the end of the list is not being found? Node* sort_list(Node* head) { Node * temp; Node * curr; for(bool didSwap = true; didSwap; ) { didSwap = false; for(curr = head; curr->next != NULL; curr = curr->next) { if(curr->key > curr->next->key) { temp = curr; curr = curr->next; curr->next = temp; didSwap = true; } cout << curr->next->key << endl; } } return head; } If I change the code so that the keys (data) are swapped, then the function works properly but for some reason I am not able make it work by manipulating only pointers.

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  • (1 2 3 . #<void>)- heapsort

    - by superguay
    Hello everybody: I tried to implement a "pairing heap" with all the regular operations (merge, delete-min etc.), then I've been requested to write a function that would sort a list using my newly constructed heap implementation. Unfortunately it seems that someting goes wrong... Here's the relevant code: (define (heap-merge h1 h2) (cond ((heap-empty? h1) h2) ((heap-empty? h2) h1) (else (let ((min1 (heap-get-min h1)) (min2 (heap-get-min h2))) (if ((heap-get-less h1) min1 min2) (make-pairing-heap (heap-get-less h1) min1 (cons h2 (heap-get-subheaps h1))) (make-pairing-heap (heap-get-less h1) min2 (cons h1 (heap-get-subheaps h2)))))))) (define (heap-insert element h) (heap-merge (make-pairing-heap (heap-get-less h) element '()) h)) (define (heap-delete-min h) (define (merge-in-pairs less? subheaps) (cond ((null? subheaps) (make-heap less?)) ((null? (cdr subheaps)) (car subheaps)) (else (heap-merge (heap-merge (car subheaps) (cadr subheaps)) (merge-in-pairs less? (cddr subheaps)))))) (if (heap-empty? h) (error "expected pairing-heap for first argument, got an empty heap ") (merge-in-pairs (heap-get-less h) (heap-get-subheaps h)))) (define (heapsort l less?) (let aux ((h (accumulate heap-insert (make-heap less?) l))) (if (not (heap-empty? h)) (cons (heap-get-min h) (aux (heap-delete-min h)))))) And these are some selectors that may help you to understand the code: (define (make-pairing-heap less? min subheaps) (cons less? (cons min subheaps))) (define (make-heap less?) (cons less? '())) (define (heap-get-less h) (car h)) (define (heap-empty? h) (if (null? (cdr h)) #t #f)) Now lets get to the problem: When i run 'heapsort' it returns the sorted list with "void", as you can see: (heapsort (list 1 2 3) <) (1 2 3 . #)..HOW CAN I FIX IT? Regards, Superguay

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  • Writing a JMS Publisher without "public static void main"

    - by The Elite Gentleman
    Hi guys, Every example I've seen on the web, e.g. http://www.codeproject.com/KB/docview/jms_to_jms_bridge_activem.aspx, creates a publisher and subscriber with a public static void main method. I don't think that'll work for my web application. I'm learning JMS and I've setup Apache ActiveMQ to run on JBoss 5 and Tomcat 6 (with no glitches). I'm writing a messaging JMS service that needs to send email asynchronously. I've already written a JMS subscriber that receives the message (the class inherits MessageListener). My question is simple: How do I write a publisher that will so that my web applications can call it? Does it have to be published somewhere? My thought is to create a publisher with a no-attribute constructor (in there) and get the MessageQueue Factory, etc. from the JNDI pool (in the constructor). Is my idea correct? How do I subscribe my subscriber to the Queue Receiver? (So far, the subscriber has no constructor, and if I write a constructor, do I always subscribe myself to the Queue receiver?) Thanks for your help, sorry if my terminology is not up to scratch, there are too many java terminologies that I get lost sometimes (maybe a java GPS will do! :-) ) PS Is there a tutorial out there that explains how to write a "better" (better can mean anything, but in my case it's all about performance in high demand requests) JMS Publisher and Subscriber that I can run on Application Server such as JBoss or Glassfish? Don't forget that the JMS application will needs a "guarantee" uptime as many applications will use this.

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  • Apples, oranges, and pointers to the most derived c++ class

    - by Matthew Lowe
    Suppose I have a bunch of fruit: class Fruit { ... }; class Apple : public Fruit { ... }; class Orange: public Fruit { ... }; And some polymorphic functions that operate on said fruit: void Eat(Fruit* f, Pesticide* p) { } void Eat(Apple* f, Pesticide* p) { ingest(f,p); } void Eat(Orange* f, Pesticide* p) { peel(f,p); ingest(f,p); } OK, wait. Stop right there. Note at this point that any sane person would make Eat() a virtual member function of the Fruit classes. But that's not an option, because I am not a sane person. Also, I don't want that Pesticide* in the header file for my fruit class. Sadly, what I want to be able to do next is exactly what member functions and dynamic binding allow: typedef list<Fruit*> Fruits; Fruits fs; ... for(Fruits::iterator i=fs.begin(), e=fs.end(); i!=e; ++i) Eat(*i); And obviously, the problem here is that the pointer we pass to Eat() will be a Fruit*, not an Apple* or an Orange*, therefore nothing will get eaten and we will all be very hungry. So what I really want to be able to do instead of this: Eat(*i); is this: Eat(MAGIC_CAST_TO_MOST_DERIVED_CLASS(*i)); But to my limited knowledge, such magic does not exist, except possibly in the form of a big nasty if-statement full of calls to dynamic_cast. So is there some run-time magic of which I am not aware? Or should I implement and maintain a big nasty if-statement full of dynamic_casts? Or should I suck it up, quit thinking about how I would implement this in Ruby, and allow a little Pesticide to make its way into my fruit header?

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  • Void* array casting to float, int32, int16, etc.

    - by Griffin
    Hey guys, I've got an array of PCM data, it could be 16 bit, 24 bit packed, 32 bit, etc.. It could be signed, or unsigned, and it could be 32 or 64 bit floating point. It is currently stored as a "void**" matrix, indexed by channel, then by frame. The goal is to allow my library to take in any PCM format and buffer it, without requiring manipulation of the data to fit a designated structure. If the A/D converter spits out 24 bit packed arrays of interleaved PCM, I need to accept it gracefully. I also need to support 16 bit non interleaved, as well as any permutation of the above formats. I know the bit depth and other information at runtime, and I'm trying to code efficiently while not duplicating code. What I need is an effective way to cast the matrix, put PCM data into the matrix, and then pull it out later. I can cast the matrix to int32_t, or int16_t for the 32 and 16 bit signed PCM respectively, I'll probably have to store the 24 bit PCM in an int32_t for 32 bit, 8 bit byte systems as well. Can anyone recommend a good way to put data into this array, and pull it out later? I'd like to avoid large sections of code which look like: switch( mFormat ) { case 1: // unsigned 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (uint8_t*)pcm[i]; break; case 2: // signed 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (int8_t*)pcm[i]; break; case 3: // unsigned 16 bit ... Limitations: I'm working in C/C++, no templates, no RTTI, no STL. Think embedded. Things get trickier when I have to port this to a DSP with 16 bit bytes. Does anybody have any useful macros they might be willing to share? Thanks, -Griff

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  • HREF link that targets nothing, does not want to use hash or void(0)

    - by Mattis
    I have a link that I want to be able to click to trigger a piece of jQuery code. Currently I have <a href="#" id="foo">Link</a> and $('#foo').click(function(){ // Do stuff }); which works well. But, I have always hated using hash in this way. The page flickers and the hash is added to the page url. One alternative is to use <a href="javascript:void(0);" id="foo">Link</a> but I also dislike seeing that piece of code in the browser status bar. It looks tacky. What I'd rather have is an explanatory javascript placeholder that does nothing, like <a href="javascript:zoom();" id="foo">Link</a> which actually works, but throws an ReferenceError in the javascript console since there are no such function. What's the minimum definition of a function that does nothing? Are there any other alternatives? Should I just skip the link and use something like <span id="foo" style="cursor:pointer;cursor:hand;">Link</span> instead?

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  • Casting pointer to object to void * in C++

    - by JB
    I've been reading StackOverflow too much and started doubting all the code I've ever written, I keep thinking "Is that undefined behavour?" even in code that has been working for ages. So my question - Is it safe and well defined behavour to cast a pointer to an object (In this case abstract interface classes) to a void* and then later on cast them back to the original class and call method using them? I'm fully aware that the code that does this is probably awful. I wouldn't even consider writing it like this now (this is old code which I don't really want to change), so I'm not looking for a discussion of better ways to do this. I already know how to write it better if I ever did this again. But if it's actually broken to rely on this in C++ then I'll have to look at changing the code, if it's merely awful code then changing it won't be a priority. I would have had no doubts about something this simple a year or two ago but as my understanding of C++ increases I actually find I have more and more worries about code being safe under the standards even if it works perfectly well. Perhaps reading too much stack overflow is a bad thing for productivity sometimes :P

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  • Passing functor and function pointers interchangeably using a templated method in C++

    - by metroxylon
    I currently have a templated class, with a templated method. Works great with functors, but having trouble compiling for functions. Foo.h template <typename T> class Foo { public: // Constructor, destructor, etc... template <typename Func> void bar(T x, Func f); }; template <typename T> template <typename Func> Foo::bar(T x, Func f) { /* some code here */ } Main.cpp #include "Foo.h" template <typename T> class Functor { public: Functor() {} void operator()(T x) { /* ... */ } private: /* some attributes here */ }; void Function(T x) { /* ... */ } int main() { Foo<int> foo; foo.bar(2, Functor); // No problem foo.bar(2, Function); // <unresolved overloaded function type> return 0; }

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  • Pointer-Safe Objects?

    - by cam
    Would it be smart to have a vector in an object with a list of pointers that point to it? This way when the object is deleted, it could delete all the pointers pointing to it to prevent a null-pointer exception?

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