Search Results

Search found 21111 results on 845 pages for 'null pointer'.

Page 431/845 | < Previous Page | 427 428 429 430 431 432 433 434 435 436 437 438  | Next Page >

• How to set a reference from one object to another?

  - by Tzur Gazit

  Hi, Imagine the obvious model of employees and departments, where each employee must refer to a single department, and each department may have none to many employees. For Employee I have a pointer to Department, and I set its value to the address of the object of the relevant Department. When I try to save the Employee I get an error: 2010-04-07 10:05:22.491 CoreData2[1112:207] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[NSCFDictionary setObject:forKey:]: attempt to insert nil value (key: Department)' I tried, just for testing, to make the reference from Employee to Department optional, but I get the same result. I'm having my first steps in CoreData so please be as clear and simple as you can. Thanks, Tzur.

  Read the article

• FIFO implementation

  - by Narek

  While implementing a FIFO I have used the following structure: struct Node { T info_; Node* link_; Node(T info, Node* link=0): info_(info), link_(link) {} }; I think this a well known trick for lots of STL containers (for example for List). Is this a good practice? What it means for compiler when you say that Node has a member with a type of it's pointer? Is this a kind of infinite loop? And finally, if this is a bad practice, how I could implement a better FIFO. EDIT: People, this is all about implemenation. I am enough familiar with STL library, and know a plenty of containers from several libraries. Just I want to discuss with people who can gave a good implementation or a good advice.

  Read the article

• What is a practical, real world example of the Linked List?

  - by JStims

  I understand the definition of a Linked List, but how can it be represented and related to a common concept or item? For example, inheritance in OOP can be related to automobiles. All (most) automobiles in real life are the essentially same thing; an automobile has an Engine, you can start() it, you can make the car go(), stop() and so on. An automobile would typically have a maximum passenger capacity but it would differ between a Bus and a SportsCar, which are both automobiles. Is there some real life, intuitive example of the plain ole' singly Linked List like we have with inheritance? The typical textbook Linked List example shows a node with an integer and a pointer to the next, and it just doesn't seem very useful. Your input is appreciated.

  Read the article

• How can I find the places of system calls of my program?

  - by Lucky Man

  From strace manual: -i Print the instruction pointer at the time of the system call. I straced my programm: strace -i prog As a result I got a lot of system calls. One of them: [000da49c] open("./rabbit.o", O_RDONLY) = 3 But disassembled instruction at this address of prog doesn't call any syscall (hte editor): da49c ! mov r7, ip What is wrong? How can I find the places of system calls of my program? P.S. Architecture of my device doesn't support GDB-command catch syscall.

  Read the article

• How to stop toggle event from being fired multiple times on mouseenter/mouseleave?

  - by Clean

  Hi, I'm using jQuery to toggle the visibility of a using the jQuery toggle method. The toggle is fired on the mouseenter and mouseleave event, thus creating the effect of the div to fold out on mouseenter and fold in on mouseleave. Problem is, if the user drags the mouse over the a few times and then leaves the , the div will toggle in and out several times. This can happen if the user accidentally moves around the mouse pointer in the are. Do anyone have any idea on how I can avoid this behavior? Thanx!

  Read the article

• How do I read an arbitrary chunk from a PNG file?

  - by Mason Wheeler

  I've got some custom metadata to put into a PNG file. It's being saved through libpng, and it's not difficult to write out a custom chunk. I just call png_write_chunk with the name, length and data. But I can't see how to get the data back out again. I'd expect there to be a png_read_chunk function that takes a chunk name and returns a pointer to the data or something like that, but there's nothing like that in png.h. Does anyone know how to accomplish this?

  Read the article

• 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.

  Read the article

• Container of shared_ptr's but iterate with raw pointers

  - by Sean Lynch

  I have a class that holds a list containing boost::shared_ptrs to objects of another class. The class member functions that give access to the elemets in the list return raw pointers. For consistency I'd also like to be able to iterate with raw pointers instead of shared_ptrs. So when I dereference the list iterator, I'd like to get raw pointer, not a shared_ptr. I assume I need to write a custom iterator for this. Is this correct? If so can someone point me in the right direction - I've never done this before.

  Read the article

• C++ and Scripting.Dictionary from scrrun.dll

  - by MaxFX

  Hello. I have some trouble with Scripting.Dictionary in C++. I'm trying to use interface IDictionary via smart pointer but methods of creating object don't work and I can't understand why. CoInitialize(NULL); IDictionaryPtr dict; dict.CreateInstance(__uuidof(Dictionary)); _variant_t num1 = 1; _variant_t num2 = 2; dict->Add(&num1, &num2); long i; dict->get_Count(&i); cout << i << "\n"; But method Add does not work and cout of elements in dictionary is always 0. How correct to use Scripting.Dictionary in that case. PS.: I'm getting Scripting interfaces by #import "scrrun.dll"

  Read the article

• How can I tell NetBeans to use the latest available version of a JAR for a library?

  - by Freiheit

  I have a Netbeans project with a library defined which includes several JARs. These JARs are versioned like lib\blah\com.blah.wibble.jar_0.6.1.201004161543 . These are nightly builds from another project so that version changes often. I know I can point NetBeans at the specific JARs with the version name, but this means that every time I get a new version I have to update the NetBeans library. I can also strip the version name from the JARs, but this makes it hard to track down bugs. "What version of the blah JARs?" is usually the second thing we ask when we find a bug. Is it possible to tell Netbeans to use included com.blah.wibble.jar_[??????] where ???? is some sort of automatic pointer to use the latest available version?

  Read the article

• Using a WinForm as a Windows Installer Custom Action

  - by Serexx

  Hello - I am working on in installer project that needs to gather some info and act on it during the install (mainly online key retreival and registration). The Setup Project UserInterface templates seem inflexible and poorly documented so I am looking at opening a WinForm as a Custom Action. I know this is possible because I see reference to it in many places but this is my first Windows Installer experience and so far it is mired in googled contradictions, partial or outdated information and guesswork... erg.... Does anyone have (even a pointer to) a clear concise description of how one gets this done in a VS 2008 WinForm project... Many thanks for inputs

  Read the article

• compilation error: request member in something not a structure of union

  - by Fantastic Fourier

  Hi everybody, I'm having the above error request member rv in something not a structure of union. I've googled it and several answers told me it's when working with a pointer but tries to access it as a struct, where I should be using -> instead of . int foo(void * arg, struct message * msg) { struct fd_info * info = (struct something *) arg; int * socks[MAX_CONNECTION]; socks = &(info->_socks); // where int * _socks[MAX_CONNECTION] in struct info // do other things rv = sendto(socks[i], &msg, sizeof(&msg), NULL, &(csys->client_address), sizeof(csys->client_address)); ... } The problem is all of the arguments i have are pointers. i'm confused as to what is wrong. thanks to any comments/thoughts.

  Read the article

• Unable to use 'class' as a key in NSDictionary with Xcode 4.5

  - by Vivin Paliath

  I'm trying to use a class as a key in an NSDictionary. I looked at the answer to this question and what I have is pretty much the same; I'm using setObject: forKey:. However, XCode complains, saying Incompatible pointer types sending 'Class' to parameter of type 'id<NSCopying>'. The call I have is: [_bugTypeToSerializerDictionary setObject: bugToStringSerializer forKey: [bugToStringSerializer serializedObjectType]]; bugToStringSerializer is an instance of BugToStringSerializer whose concrete implementations implement serializedObjectType. An example of a concrete implementation looks like this: - (Class) serializedObjectType { return [InfectableBug class]; } What am I doing wrong here?

  Read the article

• EXC_BAD_ACCESS when not using self.

  - by chris

  I got nabbed by the following bug again and would like some clarification to exactly why it is a bug. I have a simple UITableView that loads some data: // myclass.h @property (nonatomic, retain) NSArray *myData // myclass.m @synthesize myData; - (void) viewDidLoad { ... myData = someDataSource // note the lack of self } - (UITableViewCell *) cellForRowAtIndexPath ... { ... cell.textLabel.text = [self.myData objectAtIndex:indexPath.row]; // EXC_BAD_ACCESS } The table first loads fine, but when scrolling up enough that one of the cells is totally out of the view I then get the EXC_BAD_ACCESS error. Am I missing something in regards to @property retain. My understanding is that it releases anything that the pointer was previously pointing to before the reassignment. If I am correct then why would not using self. cause any problems? Thanks for the help.

  Read the article

• How to dynamically replace a method implement in ObjC2?

  - by Abhi

  I am trying to learn how to write plugins using SIMBL. I got my plugin to load with the target application, and also know the method that I wish to override. However, I am not able to use class_getInstanceMethod correctly based on snippets on the Internet. Have things changed in OSX 10.6 and/or ObjC2? The following code from culater.net gives "Dereferencing pointer to incomplete type": BOOL DTRenameSelector(Class _class, SEL _oldSelector, SEL _newSelector) { Method method = nil; // First, look for the methods method = class_getInstanceMethod(_class, _oldSelector); if (method == nil) return NO; method->method_name = _newSelector; return YES; } Is there a complete example of how to override a method using SIMBL plugins? Thanks!

  Read the article

• Objects in interface

  - by Peter Kowalchuk

  I created my own object, PKSurvey. In the interface of the View Controller I can define a pointer to it, then in a method I can alloc it and have an instance. How do I keep the instance beyond the method where it was allocated? I assign values in one method and want to be able to use those values in other methods. Should I allocate it in the viewDidLoad method or should I do it somewhere else? @interface DIrectionalDrillerViewController : UIViewController { PKSurvey *Survey=[PKSurvey new]; ---------------- - (void)viewDidLoad { [Survey new];

  Read the article

• drupal bootstrap script: how to get list of all nodes of type x?

  - by groovehunter

  hi. I create a custom import and export, at the moment as an external script (via bootstrap), i plan to create a module in a more generic fashion lateron. I am building a frontend for nagios and for our host management and nagios configuration btw. Maybe it might become useful for other environments (networkmanagement) Now i need to know how to get list of all nodes of type x? I want to avoid direct SQL. A suggestion i got was to make an rss and parse it but i acess the drupal db a dozen times to extract various nodes, so it feels strange to do a web request for one thing So what i am looking for as newbie drupal dev is just a pointer to basic search module api for this task TIA florian

  Read the article

• generic async loading method for page web scripts?

  - by boomhauer

  The google analytics code went to an async load model some time back. I've noticed that a lot of the other scripts I use on many sites are causing slow load times - specifically the addthis script and the facebook like button. I'm noticing that the slow load times of these scripts is causing the google bot to calc my page loadtimes as being much slower than previously. I'd like to know if there is a standard/generic way of causing these scripts to load async as well, or perhaps a pointer to someone who has done the work for this already. Seems this would be a popular thing to do, but not much luck searching around.

  Read the article

• how to draw a line between two labels in a panel where labels are added during runtime

  - by vybhav

  A panel contains two labels which are generated by mouse clicks on the panel. I want to connect these two labels by drawing a line between them probably by dragging the mouse pointer from one label to another. There are two events here - one is clicking on the panel to generate the labels and the second is connecting these two labels (mouse pressed, mouse dragged and mouse released events). Both these event need to call the repaint() method but for different purposes. But there can be only one paint() method. The problem is when I connect these two labels, the line comes up but the rest of the components on the panel disappear.

  Read the article

• How to improve performance

  - by Ram

  Hi, In one of mine applications I am dealing with graphics objects. I am using open source GPC library to clip/merge two shapes. To improve accuracy I am sampling (adding multiple points between two edges) existing shapes. But before displaying back the merged shape I need to remove all the points between two edges. But I am not able to find an efficient algorithm that will remove all points between two edges which has same slope with minimum CPU utilization. Currently all points are of type PointF Any pointer on this will be a great help.

  Read the article

• IO completion port key confusion

  - by Richard Tew

  I'm writing an IO completion port based server (source code here) using the Windows DLL API in Python using the ctypes module. But this is a pretty direct usage of the API and this question is directed at those who have a knowledge of IOCP, not Python. As I understand the documentation for CreateIoCompletionPort, you specify your "user defined" completion key when you call this function with a file handle (in my case a socket) you are associating with the created IOCP. When you get around to calling GetQueuedCompletionStatus, you get a completion key value along with a pointer to an overlapped object. The completion key should identify what overlapped object and request has completed. However, let's say I pass in 100 as the completion key in my CreateIoCompletionPort call with an overlapped object. When the same overlapped object has its IO completed and it arrives back through GetQueuedCompletionStatus, the completion key that accompanies it is much larger and bares no resemblance to the original value of 100. Am I misunderstanding how the completion key works, or must I be doing it wrong in the source code I linked above?

  Read the article

• Returning a C++ reference in a const member functionasses

  - by Chris Kaminski

  A have a class hierarchy that looks somethign like this: class AbstractDataType { public: virtual int getInfo() = 0; }; class DataType: public AbstractDataType { public: virtual int getInfo() { }; } class Accessor { DataType data; public: const AbstractDataType& getData() const { return(data); } } Well, GCC 4.4 reports: In member function ‘const AbstractDataType& Accessor::getData() const’: error: invalid initialization of reference of type ‘const AbstractDataType&’ from expression of type ‘const DataType’ Where am I going wrong - is this a case where I MUST use a pointer?

  Read the article

• Data-separation in a Symfony Multi-tenant app using Doctrine

  - by Prasad

  I am trying to implement a multi-tenant application, that is - data of all clients in a single database - each shared table has a tenant_id field to separate data I wish to achieve data separation by adding where('tenant_id = ', $user->getTenantID()) {pseudoc-code} to all SELECT queries I could not find any solution up-front, but here are possible approaches I am considering. 1) crude approach: customizing all fetchAll and fetchOne functions in every class (I will go mad!) 2) using listeners: possibly coding for the preDqlSelect event and adding the 'where' to all queries 3) override buildQuery(): could not find an example of this for front-end 4) implement contentformfilter: again need a pointer Would appreciate if someone could validate these & comment on efficieny, suitability. Also, if anyone has achieved multitenancy using another strategy, pl share. Thanks

  Read the article

• Place an object on top of stack in ILGenerator

  - by KiNGPiN

  I have to pass a function an instance of an object, so obviously all the information to be taken as argument is to be loaded onto the evaluation stack Here is the code that i am looking for someClass SomeObject = new someClass(); il.Emit(OpCodes.LoadObject, SomeObject); il.Emit(OpCodes.CallVirt, MethodInfo Function); public void Function(Object obj) { Type type = typeof(obj); //do something w.r.t to the type } I dont require any information stored in the class just the type and i cannot use any of the primitive types to take my decision on Last i read that i can use a pointer to load the type using some opcodes ... but i am completely lost here, any help or pointers to the right direction would be great :)

  Read the article

• Unable to create unmanaged object using new keyword in managed C++

  - by chair79

  Hi all, I've created a class with a boost::unordered_map as a member, Linkage.h #ifndef LINKAGE_H #define LINKAGE_H #include <boost/unordered_map.hpp> class Linkage { private: boost::unordered_map<int, int> m_IOMap; public: .... }; Linkage.cpp #include "stdafx.h" ... // methods and in the managed side of C++, I try to create the pointer of the obj: private: System::Void Form1_Load(System::Object^ sender, System::EventArgs^ e) { Linkage* m_pLink = new Linkage(); ..... } However this produces errors: Error 4 error LNK2005: "private: static unsigned int const boost::detail::type_with_alignment_imp<4>::found" (?found@?$type_with_alignment_imp@$03@detail@boost@@$$Q0IB) already defined in Proj_Test.obj Linkage.obj ..... Error 7 fatal error LNK1169: one or more multiply defined symbols found Could anyone explain to me pls? Thanks.

  Read the article

< Previous Page | 427 428 429 430 431 432 433 434 435 436 437 438  | Next Page >