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  • boost::dynamic_pointer_cast with const pointer not working ?

    - by ereOn
    Hi, Let's say I have two classes, A and B, where B is a child class of A. I also have the following function: void foo(boost::shared_ptr<const A> a) { boost::shared_ptr<const B> b = boost::dynamic_pointer_cast<const B>(a); // Error ! } Compilation with gcc gives me the following errors: C:\Boost\include/boost/smart_ptr/shared_ptr.hpp: In constructor 'boost::shared_ptr< <template-parameter-1-1> >::shared_ptr(const boost::shared_ptr<Y>&, boost::detail::dynamic_cast_tag) [with Y = const A, T = const B]': C:\Boost\include/boost/smart_ptr/shared_ptr.hpp:522: instantiated from 'boost::shared_ptr<X> boost::dynamic_pointer_cast(const boost::shared_ptr<U>&) [with T = const B, U = const A]' src\a.cpp:10: instantiated from here C:\Boost\include/boost/smart_ptr/shared_ptr.hpp:259: error: cannot dynamic_cast 'r->boost::shared_ptr<const A>::px' (of type 'const class A* const') to type 'const class B*' (source type is not polymorphic) What could possibly be wrong ? Thank you.

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  • pointer to member function question

    - by Steve
    Hello, I'm trying to replicate a template I've used before with a member function, and it isn't going very well. The basic form of the function is template<class T> T Convert( HRESULT (*Foo)(T*)) { T temp; Foo(&temp); //Throw if HRESULT is a failure return temp; } HRESULT Converter(UINT* val) { *val = 1; return S_OK; } int _tmain(int argc, _TCHAR* argv[]) { std::cout << Convert<UINT>(Converter) << std::endl; return 0; } For the life of me, I can't get this to work with a member variable. I've read up on their syntax, and I can't seem to figure out how to make it work with templates. The class would be something similar to class TestClass { HRESULT Converter(UINT* val) { *val = 1; return S_OK; } }

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  • C++ - dynamic pointer of array

    - by Eagle
    Hi to all, first i would like to say i am Newbie in C++. As part of my master thesis i am writing a program in C++ which also get as parameters the variables m and d (both integers). Were d is the power of 2 (this means 2^d elements). Parameter m define the number of possible interactions between one element and the total group (2^d elements). The number of possible interactions is computed as following: \kappa = \sum_{i=0}^m\binom{d}{i} (at present i generate vector of vectors for 2^d x \kappa, but my Prof. would like me to create different statistics to different m's. My first though was to to generate a dynamic array of m arrays of different sizes... Then i though of defining a 3-dim array with the biggest needed 2d array, but also program speed is important (e.g d = 20). i would like to ask for your advice how to define such kind of dynamic array that will also be fast. Regards

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  • Write Null/Nothing value with Databinding

    - by clawson
    I have extended a MaskedTextBox component to add some functionality. The text property of the extended MaskedTextBox is bound to a DateTime? property and the format of binding is set to a time format of "HH:mm:ss" (i.e. 24hr time). So that this masked text box will capture the display a time. The extra functionality I have added is to make the component readonly unless the component is double clicked or the enter button is pressed (the back color of the control helps to inform the users if the component is locked/readonly or not). When the enter button is pressed I also suspend the bindings so that bound data is updated the users input won't be lost. The information is then written back to the value and databindings resumed when the user presses the enter key again. This all works fine up to here, with values written and displayed as would be expected. However, I also want to write the null or nothing value to the DateTime? property if the user hasn't entered any text (or invalid text but let's just stick with no text) when enter key is pressed to submit the new value. Unlike with other valid entries in the MaskedTextBox, with no text entered when i execute: Me.DataBindings("Text").WriteValue() (when 'locking' the MaskedTextBox) it then branches to the bound properties Get method as I step into each line of code in the debugger (as opposed to the Set method with other valid entries) How can I write this null/nothing/"" value to the DateTime? property when no text "" is entered into the MaskedTextBox? Thanks for the help!

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  • C Nested Structure Pointer Problem

    - by Halo
    I have a shared structure, and inside it a request structure: struct shared_data { pthread_mutex_t th_mutex_queue; struct request_queue { int min; int max; char d_name[DIR_SIZE]; pid_t pid; int t_index; } request_queue[BUFSIZE]; int count; int data_buffer_allocation[BUFSIZE]; int data_buffers[BUFSIZE][100]; }; Then I prepare a request; struct shared_data *sdata_ptr; ... ... sdata_ptr->request_queue[index].pid = pid; strcpy(sdata_ptr->request_queue[index].d_name, dir_path_name); sdata_ptr->request_queue[index].min = min; sdata_ptr->request_queue[index].max = max; And the compiler warns me that I'm doing an incompatible implicit declaration in the strcpy function. I guess that's a problem with the pointers, but isn't what I wrote above supposed to be true?

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  • some pointer to understanding GCC source code

    - by user299570
    hi, I'm student working on optimizing GCC for multi-core processor. I tried going through the source code, it is difficult to follow through it since I need to add some code to the back end. Can anyone suggest some good resource which explains the code flow through the different phases. Also suggest some development environment for debugging GCC mainly to step through the code. Is it possible on windows?

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  • getPackage() returning null when my JUnit test is run from Ant

    - by philharvey
    I'm having problems running a JUnit test. It runs fine in Eclipse, but now I'm trying to run it from the command-line using Ant. The problem is that the following code is returning null: getClass().getPackage(). I'm running my JUnit test like so: <junit fork="no" printsummary="yes" haltonfailure="no"> <classpath refid="junit.classpath" /> <batchtest fork="yes" todir="${reports.junit}"> <fileset dir="${junit.classdir}"> <include name="**/FileHttpServerTest.class" /> <exclude name="**/*$*" /> </fileset> </batchtest> <formatter type="xml" /> ... I Googled for this sort of error, and found a number of references to classloader misbehaviour. But I've found nothing gave me enough information to solve my problem. I really need getClass().getPackage() to not return null. Can anyone help me? Thanks, Phil

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  • Remove pointer object whose reference is mantained in three different lists

    - by brainydexter
    I am not sure how to approach this problem: 'Player' class mantains a list of Bullet* objects: class Player { protected: std::list< Bullet* > m_pBullet_list; } When the player fires a Bullet, it is added to this list. Also, inside the constructor of bullet, a reference of the same object is updated in CollisionMgr, where CollisionMgr also mantains a list of Bullet*. Bullet::Bullet(GameGL*a_pGameGL, Player*a_pPlayer) : GameObject( a_pGameGL ) { m_pPlayer = a_pPlayer; m_pGameGL->GetCollisionMgr()->AddBullet(this); } class CollisionMgr { void AddBullet(Bullet* a_pBullet); protected: std::list< Bullet*> m_BulletPList; } In CollisionMgr.Update(); based on some conditions, I populate class Cell which again contain a list of Bullet*. Finally, certain conditions qualify a Bullet to be deleted. Now, these conditions are tested upon while iterating through a Cell's list. So, if I have to delete the Bullet object, from all these places, how should I do it so that there are no more dangling references to it? std::list< Bullet*>::iterator bullet_it; for( bullet_it = (a_pCell->m_BulletPList).begin(); bullet_it != (a_pCell->m_BulletPList).end(); bullet_it++) { bool l_Bullet_trash = false; Bullet* bullet1 = *bullet_it; // conditions would set this to true if ( l_Bullet_Trash ) // TrashBullet( bullet1 ); continue; } Also, I was reading about list::remove, and it mentions that it calls the destructor of the object we are trying to delete. Given this info, if I delete from one list, the object does not exist, but the list would still contain a reference to it..How do I handle all these problems ? Can someone please help me here ? Thanks PS: If you want me to post more code or provide explanation, please do let me know.

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  • C++: Unknown pointer size when forward declaring (error C2036)

    - by Rosarch
    In a header file, I have forward declared two members of a namespace: namespace Foo { struct Odp typedef std::vector<Odp> ODPVEC; }; class Bar { public: Foo::ODPVEC baz; // C2036 }; The error generated by the compiler is: error C2036: 'Foo::Odp *': unknown size I'm guessing this is an issue with forward declaring Odp. How can I get around this?

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  • Reference to a pointer question

    - by Yogesh Arora
    Please refer to the code below. In this code i am storing the const char* returned by test.c_str() into a reference. My question is Will the data be correctly refering to the contents of test. I am thinking that ptr returned by test.c_str() will be a temporary and if i bound it to a reference that reference will not be valid. Is my thinking correct class RefPtrTest { std::string test; StoringClass storingClass; public: RefPtrTest(): test("hello"), storingClass(test.c_str()) { } } where StoringClass is class StoringClass { const char*& data; public: StoringClass (const char*& input): data(input) { } }

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  • Compiler error when casting to function pointer

    - by detly
    I'm writing a bootloader for the PIC32MX, using HiTech's PICC32 compiler (similar to C90). At some point I need to jump to the real main routine, so somewhere in the bootloader I have void (*user_main) (void); user_main = (void (*) (void)) 0x9D003000; user_main(); (Note that in the actual code, the function signature is typedef'd and the address is a macro.) I would rather calculate that (virtual) address from the physical address, and have something like: void (*user_main) (void); user_main = (void (*) (void)) (0x1D003000 | 0x80000000); user_main(); ...but when I try that I get a compiler error: Error #474: ; 0: no psect specified for function variable/argument allocation Have I tripped over some vagarity of C syntax here? This error doesn't reference any particular line, but if I comment out the user_main() call, it goes away. (This might be the compiler removing a redundant code branch, but the HiTech PICC32 isn't particularly smart in Lite mode, so maybe not.)

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  • Getting 'this' pointer inside dependency property changed callback

    - by mizipzor
    I have the following dependency property inside a class: class FooHolder { public static DependencyProperty CurrentFooProperty = DependencyProperty.Register( "CurrentFoo", typeof(Foo), typeof(FooHandler), new PropertyMetadata(OnCurrentFooChanged)); private static void OnCurrentFooChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { FooHolder holder = (FooHolder) d.Property.Owner; // <- something like this // do stuff with holder } } I need to be able to retrieve a reference to the class instance in which the changed property belongs. This is since FooHolder has some event handlers that needs to be hooked/unhooked when the value of the property is changed. The property changed callback must be static, but the event handler is not.

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  • Why is my Repeater null in code behind?

    - by Rob Stevenson-Leggett
    I'm just starting a new project and I am getting some really weird stuff happening. ASP.NET 3.5, VS2008. I've tried rebuild, close VS, delete everything and get from svn again but I cannot understand why the repeater in the following is null on page_load. I know this is going to be a headslapping moment. Help me out? Markup: <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="GalleryControl.ascx.cs" Inherits="Site.UserControls.GalleryControl" %> <asp:Repeater ID="rptGalleries" runat="server"> <HeaderTemplate><ul></HeaderTemplate> <ItemTemplate> <li>wqe</li> </ItemTemplate> <FooterTemplate></ul></FooterTemplate> </asp:Repeater> Code behind public partial class GalleryControl : System.Web.UI.UserControl { protected void Page_Load(object sender, EventArgs e) { rptGalleries.DataSource = new[] {1, 2, 3, 4, 5}; rptGalleries.DataBind(); } } Why is my repeater null? What the F is going on?

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  • Why is is giving me an SQL syntax error?

    - by Tibo
    Do you have any idea why i get this: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '``, `title` varchar(255) collate latin1_general_ci NOT NULL default ``,' at line 3 The code is like this (the part im having problem with...) $sql = 'CREATE TABLE `forum` ( `postid` bigint(20) NOT NULL auto_increment, `author` varchar(255) collate latin1_general_ci NOT NULL default ``, `title` varchar(255) collate latin1_general_ci NOT NULL default ``, `post` mediumtext collate latin1_general_ci NOT NULL, `showtime` varchar(255) collate latin1_general_ci NOT NULL default ``, `realtime` bigint(20) NOT NULL default `0`, `lastposter` varchar(255) collate latin1_general_ci NOT NULL default ``, `numreplies` bigint(20) NOT NULL default `0`, `parentid` bigint(20) NOT NULL default `0`, `lastrepliedto` bigint(20) NOT NULL default `0`, `author_avatar` varchar(30) collate latin1_general_ci NOT NULL default `default`, `type` varchar(2) collate latin1_general_ci NOT NULL default `1`, `stick` varchar(6) collate latin1_general_ci NOT NULL default `0`, `numtopics` bigint(20) NOT NULL default `0`, `cat` bigint(20) NOT NULL, PRIMARY KEY (`postid`) );'; mysql_query($sql,$con) or die(mysql_error()); Help would be greatly appreciated!

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  • Write pointer to file in C

    - by Sergey
    I have a stucture: typedef structure student { char *name; char *surname; int age; } Student; I need to write it to binary file. Student *s = malloc(sizeof(*s)); I fill my structure with data and then i write in to the file: fwrite(s, sizeof(*s), 1, fp); In my file doesnt exist a name and surname, it have an adresses of char*. How can i write to file a word, not an adresses?

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  • how to cast c++ smart pointer up and down

    - by user217428
    two clients communicate to each other on top of a message layer in the message body, I need include a field pointing to any data type From client A, I send the field as a shared_ptr to the message layer. I define this field as a shared_ptr in the message layer. But how can I convert this field back to shared_ptr in client B? Or should I define shared_ptr in message layer as something else? Thanks

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  • Pointer arithmetic.

    - by Knowing me knowing you
    Having code: int** a = new int*[2]; a[0] = new int(1); a[1] = new int(2); cout << "a[0] " << a[0] << '\n'; cout << "a[1] " << a[1] << '\n'; cout << "a[2] " << a[2] << '\n'; cout << "a[0] + 1 " << a[0] + 1 << '\n';//WHY THIS ISN'T == a[1] ? cout << "*(a + 1): " << *(a + 1) << '\n'; //WHY THIS IS == a[1] ? cout << "a[0] - a[1] " << static_cast<int>(a[0] - a[1])<< '\n';//WHY THIS IS == 16 not 4? cout << sizeof(int**); Questions are included right next to relevant lines in code.

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  • Question of using static_cast on "this" pointer in a derived object to base class

    - by Johnyy
    Hi, this is an example taken from Effective C++ 3ed, it says that if the static_cast is used this way, the base part of the object is copied, and the call is invoked from that part. I wanted to understand what is happening under the hood, will anyone help? class Window { // base class public: virtual void onResize() { } // base onResize impl }; class SpecialWindow: public Window { // derived class public: virtual void onResize() { // derived onResize impl; static_cast<Window>(*this).onResize(); // cast *this to Window, // then call its onResize; // this doesn't work! // do SpecialWindow- } // specific stuff };

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  • Pass temporary object to function that takes pointer

    - by Happy Mittal
    I tried following code : #include<iostream> #include<string> using namespace std; string f1(string s) { return s="f1 called"; } void f2(string *s) { cout<<*s<<endl; } int main() { string str; f2(&f1(str)); } But this code doesn't compile. What I think is : f1 returns by value so it creates temporary, of which I am taking address and passing to f2. Now Please explain me where I am thinking wrong?

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  • Getting a file pointer from file descriptor

    - by Naga Kiran
    In PHP 5.2.3, "fdopen" was used to read/write to a file descriptor that's opened by another application. fdopen(<fileDescriptorId>,"rw"); //It worked fine with PHP 5.2.3 After upgrading PHP to 5.3.2, it's throwing "undefined reference to 'fdopen' function". Please suggest whats the replacement for this in PHP 5.3.2 or any workaround.

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  • Pointer to local variable

    - by Radek Šimko
    May I have any acces to local variable in different function? If may, how? void replaceNumberAndPrint(int array[3]) { printf("%i\n", array[1]); printf("%i\n", array[1]); } int * getArray() { int myArray[3] = {4, 65, 23}; return myArray; } int main() { replaceNumberAndPrint(getArray()); } The output of the piece of code above: 65 4202656 What am i doing wrong? What the "4202656" means?? Do I have to copy the whole array in the replaceNumberAndPrint() function to be able to access to it more than first times?

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  • Release an object without a pointer?

    - by Kai Friis
    I’ve just started developing for iPhone and am trying to get my head around memory management. I made a small program that shows a map and an annotation on the map. For the annotation I made a simple class that implements the MKAnnotation protocol. To create and add the annotation I wrote this: [self.myMapView addAnnotation:[[MyAnnotation alloc] init]]; It worked fine until I tried to release the object. Nothing to release. This is what I would have done in C#, I guess it doesn’t work without garbage collection? So is this the only way to do it? MyAnnotation *myAnnotation = [[MyAnnotation alloc] init]; [self.myMapView addAnnotation: myAnnotation]; [myAnnotation release];

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  • Calling member method on unmanaged C++ pointer from C# (I think)

    - by Jacob G
    I apologize in advance if this is a trivial question... I'm pretty C++ / unmanaged dumb. Here's a simplified analog to my setup: --In myUnmanagedObject.h in DLL: class myUnmanagedObject { public: virtual void myMethod(){} } --In MyControl.h in Assembly #1: #pragma make_public(myUnmanagedObject) [event_source(managed)] public ref class MyControl : public System::Windows::Forms::UserControl { public: myUnmanagedObject* GetMyUnmanagedObject(); } --in C# in Assembly #2: unsafe { MyControl temp = new MyControl(); myUnmanagedObject* obj = temp.GetMyUnmanagedObject(); obj-myMethod(); } I get a compile error saying that myUnmanagedObject does not contain a definition for myMethod. Assembly #2 references Assembly #1. Assembly #1 references DLL. If I compile the DLL with /clr and reference it directly from Assembly #2, it makes no difference. How, from C#, do I execute myMethod ?

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