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  • How to assign a value to an pointer-pointer passed in call by reference?

    - by mystify
    I want to achieve something similar to what these guys do here: - (NSUInteger)countForFetchRequest:(NSFetchRequest *)request error:(NSError **)error like you can see, you pass an NSError pointer and that nice method will assign a real NSError object to your pointer in case there is an error. So the cool thing about this is, that the method returns an NSUInteger but can ALSO return an NSError, without having to mess around with ugly and fat arrays or dictionaries. So how could I assign an object to the passed-in error pointer?

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  • Initializing and accessing a pointer from an array of pointers

    - by idealistikz
    Suppose I have the following: void **Init(int numElems) { //What is the best way to intialize 'ptrElems' to store an array of void *'s? void **ptrElems = malloc(numElems * sizeof(void *)); return ptrElems; } //What is the best way to return a pointer pointing at the index passed as a parameter? void **GetPtr(void **ptrElems, int index) { void **elem = elems + (index * sizeof(void *)); return elem; } First, what is the best way to intialize 'ptrElems' to store an array of pointers? I use malloc because assigning it to an array will not persist after the end of the function. Second, what is the best way to point to the pointer at the specified index? I tried typecasting the first line of the 'GetPtr' function to ensure proper pointer arithmetic, but I receive the warning, 'initialization from incompatible pointer type'. Is it necessary to typecast?

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  • Javascript: Static member variable containing object instances

    - by tom
    I have the following: function Preferences() { } Preferences.players = { 'player1': new Player() } players is a static member variable of Preferences and I'm trying to make it an object containing an instance of a Player. However, it doesn't appear to let me do this. It seems like it will allow me to define players if I make it a non-static member variable however. Like so: function Preferences() { var players = { 'player1' : new Player() } } Is it possible to create a static member variable containing instances of an object in JS?

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  • How do you delete a pointer without deleting the data the pointer points to?

    - by Faken
    I have a pointer that points to an array and another pointer referencing the same array. How do i delete any one of those pointers without killing the array such that the second undeleted pointer still works? for example: int* pointer1 = new int [1000]; int* pointer2; pointer2 = pointer1; Now i want to get rid of pointer1, how would i do it such that i can continue to access the array normaly through pointer2?

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  • boost::function function pointer to parameters?

    - by high6
    How does boost::function take a function pointer and get parameters from it? I want wrap a function pointer so that it can be validated before being called. And it would be nice to be able to call it like boost::function is with the () operator and not having to access the function pointer member. Wrapper func; func(5); //Yes :D func.Ptr(5) //Easy to do, but not as nice looking

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  • Detect pointer arithmetics because of LARGEADDRESSAWARE

    - by Suma
    I would like to switch my application to LARGEADDRESSAWARE. One of issues to watch for is pointer arithmetic, as pointer difference can no longer be represented as signed 32b. Is there some way how to find automatically all instances of pointer subtraction in a large C++ project? If not, is there some "least effort" manual or semi-automatic method how to achieve this?

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  • Determining if Memory Pointer is Valid - C++

    - by Jim Fell
    It has been my observation that if free( ptr ) is called where ptr is not a valid pointer to system-allocated memory, an access violation occurs. Let's say that I call free like this: LPVOID ptr = (LPVOID)0x12345678; free( ptr ); This will most definitely cause an access violation. Is there a way to test that the memory location pointed to by ptr is valid system-allocated memory? It seems to me that the the memory management part of the Windows OS kernel must know what memory has been allocated and what memory remains for allocation. Otherwise, how could it know if enough memory remains to satisfy a given request? (rhetorical) That said, it seems reasonable to conclude that there must be a function (or set of functions) that would allow a user to determine if a pointer is valid system-allocated memory. Perhaps Microsoft has not made these functions public. If Microsoft has not provided such an API, I can only presume that it was for an intentional and specific reason. Would providing such a hook into the system prose a significant threat to system security? Situation Report Although knowing whether a memory pointer is valid could be useful in many scenarios, this is my particular situation: I am writing a driver for a new piece of hardware that is to replace an existing piece of hardware that connects to the PC via USB. My mandate is to write the new driver such that calls to the existing API for the current driver will continue to work in the PC applications in which it is used. Thus the only required changes to existing applications is to load the appropriate driver DLL(s) at startup. The problem here is that the existing driver uses a callback to send received serial messages to the application; a pointer to allocated memory containing the message is passed from the driver to the application via the callback. It is then the responsibility of the application to call another driver API to free the memory by passing back the same pointer from the application to the driver. In this scenario the second API has no way to determine if the application has actually passed back a pointer to valid memory.

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  • static thread function access non-static class member in C++

    - by user397390
    Class Test{ int value; static void* thread_func(void* args){ value++; } void newthread(){ pthread_create(&thread_func,...); } } I'm trying to create a thread in Class Test. Therefore compiler forces me to make thread_func static. However I cannot access the non-static member "value" anymore. It says: invalid use of member 'Class::value' in static member function Is there a way around it?

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  • Static member variable containing object instances

    - by tom
    I have the following: function Preferences() { } Preferences.players = { 'player1': new Player() } players is a static member variable of Preferences and I'm trying to make it an object containing an instance of a Player. However, it doesn't appear to let me do this. It seems like it will allow me to define players if I make it a non-static member variable however. Like so: function Preferences() { var players = { 'player1' : new Player() } } Is it possible to create a static member variable containing instances of an object in JS?

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  • MDX: Filtering a member set by a measure's table values

    - by oyvinro
    I have some numbers in a fact table, and have generated a measure which use the SUM aggregator to summarize the numbers. But the problem is that I only want to sum the numbers that are higher than, say 10. I tried using a generic expression in the measure definition, and that works of course, but the problem is that I need to be able to dynamically set that value, because it's not always 10, meaning users should be able to select it themselves. More specifically, my current MDX looks like this: WITH SET [Email Measures] AS '{[Measures].[Number Of Answered Cases], [Measures].[Max Expedition Time First In Case], [Measures].[Avg Expedition Times First In Case], [Measures].[Number Of Incoming Email Requests], [Measures].[Avg Number Of Emails In Cases], [Measures].[Avg Expedition Times Total],[Measures].[Number Of Answered Incoming Emails]}' SET [Organizations] AS '{[Organization.Id].[860]}' SET [Operators] AS '{[Operator.Id].[3379],[Operator.Id].[3181]}' SET [Email Accounts] AS '{[Email Account.Id].[6]}' MEMBER [Time.Date].[Date Period] AS Aggregate ({[Time.Date].[2008].[11].[11] :[Time.Date].[2009].[1].[2] }) MEMBER [Email.Type].[Email Types] AS Aggregate ({[Email.Type].[0]}) SELECT {[Email Measures]} ON columns, [Operators] ON rows FROM [Email_Fact] WHERE ( [Time.Date].[Date Period] ) Now, the member in question is the calculated member [Avg Expedition Times Total]. This member takes in two measures; [Sum Expedition Times] and [Nr of Expedition Times] and splits one on the other to get the average, all this presently works. However, I want [Sum Expedition Times] to only summarize values over or under a parameter of my/the user's wish. How do I filter the numbers [Sum Expedition Times] iterates through, rather than filtering on the sum that the measure gives me in the end?

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  • const member functions can call const member functions only?

    - by Abhi
    Hi all. Do const member functions call only const member functions? class Transmitter{ const static string msg; mutable int size; public: void xmit() const{ size = compute(); cout<<msg; } private: int compute() const{return 5;} }; string const Transmitter::msg = "beep"; int main(){ Transmitter t; t.xmit(); return EXIT_SUCCESS; } If i dont make compute() a const, then the compiler complains. Is it because since a const member function is not allowed to modify members, it wont allow any calls to non-consts since it would mean that the const member function would be 'indirectly' modifying the data members?

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  • OOP + MVC advice on Member Controller

    - by dan727
    Hi, I am trying to follow good practices as much as possible while I'm learning using OOP in an MVC structure, so i'm turning to you guys for a bit of advice on something which is bothering me a little here. I am writing a site where I will have a number of different forms for members to fill in (mainly data about themselves), so i've decided to set up a Member controller where all of the forms relating to the member are represented as individual methods. This includes login/logout methods, as well as editing profile data etc. In addition to these methods, i also have a method to generate the member's control panel widget, which is a constant on every page on the site while the member is logged in. The only thing is, all of the other methods in this controller all have the same dependencies and form templates, so it would be great to generate all this in the constructor, but as the control_panel method does not have the same dependencies etc, I cannot use the constructor for this purpose, and instead I have to redeclare the dependencies and same template snippets in each method. This obviously isn't ideal and doesn't follow DRY principle, but I'm wondering what I should do with the control_panel method, as it is related to the member and that's why I put it in that controller in the first place. Am I just over-complicating things here and does it make sense to just move the control_panel method into a simple helper class? Here are the basic methods of the controller: class Member_Controller extends Website_Controller { public function __construct() { parent::__construct(); if (request::is_ajax()) { $this->auto_render = FALSE; // disable auto render } } public static function control_panel() { //load control panel view $panel = new View('user/control_panel'); return $panel; } public function login() { } public function register() { } public function profile() { } public function household() { } public function edit_profile() { } public function logout() { } }

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  • command&pointer&malloc [closed]

    - by gcc
    input 23 3 4 4 42 n 23 0 9 9 n n n 3 9 9 x //according to input,i should create int pointer arrays. pointer arrays starting from 1 (that is initial arrays is arrays[1].when program sees n ,it must be jumb to arrays 2 expected output arrays[1] 3 4 5 42 arrays[2] 23 0 9 9 arrays[5] 3 9 9 x is stopper n is comman to create new pointer array i am new in this site anyone help me how can i write

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  • Initialize void pointer to point to an array

    - by idealistikz
    Suppose I have the following: typedef struct { int itemSize; int count; void *list; } Mystruct; Mystruct *InitStruct(int itemSize, int count) { Mystruct *my = malloc(sizeof(Mystruct)); my->itemSize = itemSize; my->count = count; //What is the best way to initialize list? For example: //my->list = malloc(count * sizeof(void *)); OR //my->list = malloc(count * sizeof(itemSize)); } //The following should return a pointer to the element stored at a given index void *Retrieve(const MyStruct *my, int index) { void *item; //What is the best way to return a pointer to the item at the given index from //my->list? } Mystruct is similar to an array and void *list is supposed to store the elements or pointers to the elements. Mystruct *InitStruct is a function that initializes a Mystruct pointer and void *Retrieve is a function that returns a pointer to the element stored at a given index. First, how should I initialize void* list? Should it hold the actual elements or be an array of pointers pointing to the elements? Second, using the void *Retrieve function, how do I return a pointer to the element stored at a given index in my-list?

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  • When is "this" pointer initialized in C++?

    - by skydoor
    Hi I have a question about this pointer, when an object is constructed, when it is initialized? Which means, when can I use it? The virtual table is constructed in the constructor, is the same with this pointer? For example, I have a code like this. The output is 8. Does it mean that before the constructor is entered, this pointer is already initialized? class A{ public: A() { cout<<sizeof(*this);} int i; int *p; }; int main() { A a; } If it is true, what else would happen before the constructor is entered? If it is not true, when is the this pointer initialized?

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  • How to install Microsoft Exchange 2007 as a member server

    - by O_O
    I am trying to install Microsoft Exchange 2007 to a Windows Server 2003 as a member server. I already have a Windows Server 2008 as my domain controller. I'm having a hard time figuring out what is needed to prepare the machine for Exchange 2007 installation. My specific question is: While following the procedures here in the TechNet Library , do I still need to go through with the section "How to Prepare Active Directory and Domains" and do the following commands if I am making it a member server and NOT a domain controller? ie.. setup /ps setup /p /on: setup /PrepareDomain: Thank you.

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  • Workstation 7 build 203739 - Capture Movie Mouse Pointer Not Visible

    - by BMIVM
    Hi, I have noticed that whenever I create a Capture Movie, the movie is fine but the mouse pointer is not visible at all. The clicks are on buttons file menus are executed but is hard for a viewer of the capturre movie session to follow the recording smoothly. This was not a problem in previous versions of WorkStation. Is this a bug or is there a setting I can set to see the mouse pointer? Note: VM Tools are installed, Host is Vista Ultimate Edtion SP1, x64 and the guest is a Win XP SP2. Thanks in advance for your help.

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  • VMware Workstation 7 build 203739 - Capture Movie Mouse Pointer Not Visible

    - by BMIVM
    Hi, I have noticed that whenever I create a Capture Movie, the movie is fine but the mouse pointer is not visible at all. The clicks are on buttons file menus are executed but is hard for a viewer of the capturre movie session to follow the recording smoothly. This was not a problem in previous versions of WorkStation. Is this a bug or is there a setting I can set to see the mouse pointer? Note: VM Tools are installed, Host is Vista Ultimate Edtion SP1, x64 and the guest is a Win XP SP2. Thanks in advance for your help.

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  • Can I make a derived class inherit a derived member from its base class in Java?

    - by Eric
    I have code that looks like this: public class A { public void doStuff() { System.out.print("Stuff successfully done"); } } public class B extends A { public void doStuff() { System.out.print("Stuff successfully done, but in a different way"); } public void doMoreStuff() { System.out.print("More advanced stuff successully done"); } } public class AWrapper { public A member; public AWrapper(A member) { this.member = member; } public void doStuffWithMember() { a.doStuff(); } } public class BWrapper extends AWrapper { public B member; public BWrapper(B member) { super(member); //Pointer to member stored in two places: this.member = member; //Not great if one changes, but the other does not } public void doStuffWithMember() { member.doMoreStuff(); } } However, there is a problem with this code. I'm storing a reference to the member in two places, but if one changes and the other does not, there could be trouble. I know that in Java, an inherited method can narrow down its return type (and perhaps arguments, but I'm not certain) to a derived class. Is the same true of fields?

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