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  • How to get the row number of the QComboBox in QTableWidget

    - by dreamxiuhuishan
    Here is the code, but it dos not work. Who can create the code. Thanks very much! void add() { QComboBox *ziduan = new QComboBox; ziduan->addItem("??","nd"); int row =0; int col =1; QSignalMapper* signalMapper = new QSignalMapper(this); connect(ziduan, SIGNAL(currentIndexChanged(int)), signalMapper, SLOT(map())); signalMapper->setMapping(ziduan, QString("%1-%2").arg(row).arg(col)); connect(signalMapper, SIGNAL(mapped(const QString &)),this, SIGNAL(changeZiduan(const QString &))); } void sqlGenerator::changeZiduan(const QString &position) { QStringList coordinates = position.split("-"); int row = coordinates[0].toInt(); int col = coordinates[1].toInt(); }

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  • PhysX Question about Raycasting - Setting the shape masks

    - by sweet tv
    I am trying to make the raycast give me the distance of the terrain and nothing else. But I'm not sure how to use the group Mask Filter. virtual NxShape* raycastClosestShape (const NxRay& worldRay, NxShapesType shapeType, NxRaycastHit& hit, NxU32 groups=0xffffffff, NxReal maxDist=NX_MAX_F32, NxU32 hintFlags=0xffffffff, const NxGroupsMask* groupsMask=NULL, NxShape** cache=NULL) const = 0; \param[in] groups Mask used to filter shape objects. Let's say my terrain is set in group 1. How would I use the function above?

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  • Is it possible to have "inherited partial structs" in c#?

    - by Balazs
    Is it possible to use partial structs to achieve something like this: Have an asp.net page base class with the following defined: public partial struct QuerystringKeys { public const string Username = "username"; public const string CurrentUser = "currentUser"; } Have an asp.net page, which inherits from the base class mentioned above, extend the partial declaration: public partial struct QuerystringKeys { /// <summary> /// The page number of the review instances list /// </summary> public const string Page = "page"; } The final goal is a QuerystringKeys struct with all three constant strings defined in it available to the asp.net page.

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  • "Undefined Symbols" when inheriting from stdexcept classes

    - by Austin Hyde
    Here is an exception defined in <stdexcept>: class length_error : public logic_error { public: explicit length_error(const string& __arg); }; Here is my exception: class rpn_expression_error : public logic_error { public: explicit rpn_expression_error(const string& __arg); }; Why do I get this error when <stdexcept> does not? Undefined symbols: rpn_expression_error::rpn_expression_error(/*string*/ const&), referenced from: ... ld: symbol(s) not found

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  • FOX toolkit, file concatentation

    - by Robb
    I'm using the FOX Toolkit and C++ to develop a GUI. I'm Having an issue with the FXFile::concat(...) command. The method looks like: FXFile::concat(const FXString & srcfile1, const FXString & srcfile2, const FXString & dstfile, FXbool overwrite = false And when I call it with the srcfile1 and dstfile being the same thing (because I need to simply add to srcfile1), the method does not work. dstfile is empty. Anyone have experience with FOX and this concatentation problem? I'm open to other suggestions as well, including boost.

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  • C++ 'mutable' keyword

    - by Rob
    A while ago I came across some code that marked a member variable of a class with the 'mutable' keyword. As far as I can see it simply allows you to modify a variable in a 'const' method: class Foo { private: mutable bool done_; public: void doSomething() const { ...; done_ = true; } }; Is this the only use of this keyword or is there more to it than meets the eye? I have since used this technique in a class, marking a boost::mutex as mutable allowing const functions to lock it for thread-safety reasons, but, to be honest, it feels like a bit of a hack.

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  • Converting from ANSI to Unicode

    - by Rayne
    Hi all, I'm using Visual Studio .NET 2003, and I'm trying to convert a program written in purely ANSI characters to be independent of Unicode/Multi-byte characters. The program has a callback function of pcap_loop, called "got_packet". It's defined as void got_packet(u_char *user, const struct pcap_pkthdr *header, const u_char *cpacket) { USES_CONVERSION; _TUCHAR *packet; packet = A2T(cpacket); ... } However, I get the error message error C2440: 'type cast': cannot convert from 'const u_char *' to 'ATL::CA2WEX<>' How do fix this? Thank you. Regards, Rayne

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  • Function Pointer from base class

    - by camelord
    Hi there, i need a Function Pointer from a base class. Here is the code: class CActionObjectBase { ... void AddResultStateErrorMessage( const char* pcMessage , ULONG iResultStateCode); ... } CActionObjectCalibration( ): CActionObjectBase() { ... m_Calibration = new CCalibration(&CActionObjectBase::AddResultStateErrorMessage); } class CCalibration { ... CCalibration(void (CActionObjectBase::* AddErrorMessage)(const char*, ULONG )); ... void (CActionObjectBase::* m_AddErrorMessage)(const char*, ULONG ); } Inside CCalibration in a Function occurs the Error. I try to call the Function Pointer like this: if(m_AddErrorMessage) { ... m_AddErrorMessage("bla bla", RSC_FILE_ERROR); } The Problem is, that I cannot compile. The Error Message says something like: error C2064: Expression is no Function, that takes two Arguments. What is wrong? regards camelord

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  • C++ overloading operator comma for variadic arguments

    - by uray
    is it possible to construct variadic arguments for function by overloading operator comma of the argument? i want to see an example how to do so.., maybe something like this: template <typename T> class ArgList { public: ArgList(const T& a); ArgList<T>& operator,(const T& a,const T& b); } //declaration void myFunction(ArgList<int> list); //in use: myFunction(1,2,3,4); //or maybe: myFunction(ArgList<int>(1),2,3,4);

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  • Question regarding inheritance in wxWidgets.

    - by celestialorb
    Currently I'm attempting to write my own wxObject, and I would like for the class to be based off of the wxTextCtrl class. Currently this is what I have: class CommandTextCtrl : public wxTextCtrl { public: void OnKey(wxKeyEvent& event); private: DECLARE_EVENT_TABLE() }; Then later on I have this line of code, which is doesn't like: CommandTextCtrl *ctrl = new CommandTextCtrl(panel, wxID_ANY, *placeholder, *origin, *size); ...and when I attempt to compile the program I receive this error: error: no matching function for call to ‘CommandTextCtrl::CommandTextCtrl(wxPanel*&, <anonymous enum>, const wxString&, const wxPoint&, const wxSize&)’ It seems that it doesn't inherit the constructor method with wxTextCtrl. Does anyone happen to know why it doesn't inherit the constructor? Thanks in advance for any help!

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  • Why is this default template parameter not allowed?

    - by Matt Joiner
    I have the following class: template <typename Type = void> class AlignedMemory { public: AlignedMemory(size_t alignment, size_t size) : memptr_(0) { int iret(posix_memalign((void **)&memptr_, alignment, size)); if (iret) throw system_error("posix_memalign"); } virtual ~AlignedMemory() { free(memptr_); } operator Type *() const { return memptr_; } Type *operator->() const { return memptr_; } //operator Type &() { return *memptr_; } //Type &operator[](size_t index) const; private: Type *memptr_; }; And attempt to instantiate an automatic variable like this: AlignedMemory blah(512, 512); This gives the following error: src/cpfs/entry.cpp:438: error: missing template arguments before ‘buf’ What am I doing wrong? Is void not an allowed default parameter?

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  • Can a CWinApp be placed in a DLL?

    - by jmucchiello
    I'm updating some legacy apps to Visual Studio 10 and am in linker hell. All of these DLLs derive classes from CWinApp and use AfxGetApp() to get access to the object. When I link the DLLs I get unresolved externals that look like global static objects that would get pulled in by a normal app's main(): Shell.lib(SHELL.obj) : error LNK2001: unresolved external symbol "public: static struct CRuntimeClass const CException::classCException" (?classCException@CException@@2UCRuntimeClass@@B) Shell.lib(SHELL.obj) : error LNK2001: unresolved external symbol "public: static struct CRuntimeClass const CFrameWnd::classCFrameWnd" (?classCFrameWnd@CFrameWnd@@2UCRuntimeClass@@B) Shell.lib(SHELL.obj) : error LNK2001: unresolved external symbol "public: static class CRect const CFrameWnd::rectDefault" (?rectDefault@CFrameWnd@@2VCRect@@B) My current combination of ignore default libraries and additional libraries (the method you can easily google to find the answer to linker hell) is: msvcprtd.lib,mfc100d.lib,mfcs100d.lib,libcmtd.lib When I add nafxcwd.lib (the mfc library), these three external symbols resolve but I end up with a bunch of other duplicate symbols (requiring the use of /FORCE:MULTIPLE) and in end __argc and __argv become unresolved. So the basic question is: Can you link a DLL containing a CWinApp in VS10? How do you setup the linker to do it?

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  • What does the '&' operator do in C++?

    - by rascher
    n00b question. I am a C guy and I'm trying to understand some C++ code. I have the following function declaration: int foo(const string &myname) { cout << "called foo for: " << myname << endl; return 0; } How does the function signature differ from the equivalent C: int foo(const char *myname) Is there a difference between using string *myname vs string &myname? What is the difference between & in C++ and * in C to indicate pointers? Similarly: const string &GetMethodName() { ... } What is the & doing here? Is there some website that explains how & is used differently in C vs C++?

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  • Unresolved symbol when inheriting interface

    - by LeopardSkinPillBoxHat
    It's late at night here and I'm going crazy trying to solve a linker error. If I have the following abstract interface: class IArpPacketBuilder { public: IArpPacketBuilder(const DslPortId& aPortId); virtual ~IArpPacketBuilder(); // Other abstract (pure virtual methods) here... }; and I instantiate it like this: class DummyArpPacketBuilder : public IArpPacketBuilder { public: DummyArpPacketBuilder(const DslPortId& aPortId) : IArpPacketBuilder(aPortId) {} ~DummyArpPacketBuilder() {} }; why am I getting the following error when linking? Unresolved symbol references: IArpPacketBuilder::IArpPacketBuilder(DslPortId const&): ppc603_vxworks/_arpPacketQueue.o IArpPacketBuilder::~IArpPacketBuilder(): ppc603_vxworks/_arpPacketQueue.o typeinfo for IArpPacketBuilder: ppc603_vxworks/_arpPacketQueue.o *** Error code 1 IArpPacketBuilder is an abstract interface, so as long as I define the constructors and destructions in the concrete (derived) interface, I should be fine, no? Well it appears not.

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  • gdb: SIGTRAP on std::string::c_str() call

    - by sheepsimulator
    So I've been trying to use gdb to return the value of a string I have by calling > print <member variable name>.c_str() But everytime I do so, I get this: Program received signal SIGTRAP, Trace/breakpoint trap. <some address> in std::string::c_str() from /usr/lib/libstdc++.so.6 GDB remains in the frame where the signal was received. To change this behavior use "set unwindonsignal on" Evaluation of the expression containing the function (std::string::c_str() const) will be abandoned. Two questions: Why/how is the standard library throwing SIGTRAP? I checked basic_string.h and c_str() is defined as: const _CharT* c_str() const { return _M_data(); } I don't see any SIGTRAP-throwing here... is there a way to get around this SIGTRAP? How can I read the text value of the std::string out (without getting some crazy extension library) in gdb?

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  • What causes my borderless C++/CLI app to crash when overriding WndProc?

    - by Ste
    I use a form with border NONE. I need to override WndProc for resize and move form. However, using this code, my app crashes! static const int WM_NCHITTEST = 0x0084; static const int HTCLIENT = 1; static const int HTCAPTION = 2; protected: virtual void Form1::WndProc(System::Windows::Forms::Message %m) override { switch (m.Msg) { case WM_NCHITTEST: if (m.Result == IntPtr(HTCLIENT)) { m.Result = IntPtr(HTCAPTION); } break; } Form1::WndProc(m); } virtual System::Windows::Forms::CreateParams^ get() override { System::Windows::Forms::CreateParams^ cp = __super::CreateParams; cp->Style |= 0x40000; return cp; } How can I fix my code not to crash but still allow my form to be moved and resized?

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  • Sort CMap Key by String Length

    - by Yan Cheng CHEOK
    Previously, I am using STL map to perform the mentioned task. struct ltstr { bool operator()(std::string s1, std::string s2) const { const int l1 = s1.length(); const int l2 = s2.length(); if (l1 == l2) { // In alphabetical order. return s1.compare(s2) < 0; } // From longest length to shortest length. return l1 > l2; } }; std::map<std::string, int, ltstr> m; How can I perform the same task using CMap? // How to make key sorted by string length? CMap<CString, LPCTSTR, int, int> m;

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  • How to find item selected from customContextMenuRequested() on QTreeView item?

    - by vinaym
    I have implemented contextual menus in QTreeView items with the following code MyDerivedQTreeView->setModel(MyDerivedQAbstractItemModel); MyDerivedQTreeView->setContextMenuPolicy(Qt::CustomContextMenu); connect(MyDerivedQTreeView, SIGNAL(customContextMenuRequested(const QPoint &)), MyDerivedQAbstractItemModel(), SLOT(contextualMenu(const QPoint &))); void MyDerivedQAbstractItemModel::contextualMenu(const QPoint& point) { QMenu *menu = new QMenu; menu->addAction(QString("Test Item"), this, SLOT(test_slot())); menu->exec(MyDerivedQTreeView->mapToGlobal(point)); } MyDerivedQAbstractItemModel::contextualMenu() gets called and I can see the contextual menu. Problem is contextual menu should be visible only if user right-clicks on an item and it should be customized as per the item selected. How do I get whether/which item is selected from QPoint information? I am on Qt 4.5.3.

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  • Default values on arguments in C functions and function overloading in C

    - by inquam
    Converting a C++ lib to ANSI C and it seems like though ANSI C doesn't support default values for function variables or am I mistaken? What I want is something like int funcName(int foo, bar* = NULL); Also, is function overloading possible in ANSI C? Would need const char* foo_property(foo_t* /* this */, int /* property_number*/); const char* foo_property(foo_t* /* this */, const char* /* key */, int /* iter */); Could of course just name them differently but being used to C++ I kinda used to function overloading.

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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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  • What causes my borderless C++ app to crash when overriding WndProc?

    - by Ste
    I use a form with border NONE. I need to override WndProc for resize and move form. However, using this code, my app crashes! static const int WM_NCHITTEST = 0x0084; static const int HTCLIENT = 1; static const int HTCAPTION = 2; protected: virtual void Form1::WndProc(System::Windows::Forms::Message %m) override { switch (m.Msg) { case WM_NCHITTEST: if (m.Result == IntPtr(HTCLIENT)) { m.Result = IntPtr(HTCAPTION); } break; } Form1::WndProc(m); } virtual System::Windows::Forms::CreateParams^ get() override { System::Windows::Forms::CreateParams^ cp = __super::CreateParams; cp->Style |= 0x40000; return cp; } How can I fix my code not to crash but still allow my form to be moved and resized?

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  • Illegal token on right side of ::

    - by Adam Haile
    I have the following template declaration: template <typename T> void IterTable(int& rIdx, std::vector<double>& rVarVector, const std::vector<T>& aTable, const T aValue, T aLowerBound = -(std::numeric_limits<T>::max()), //illegal token on right side of '::' shows here bool aLeftOpen = true) const; Which throws the illegal token error as noted, on the line with "-(std::numeric_limits::max())". I got this code from some old linux source that I'm trying to compile on Windows. Any idea what the issue is?

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  • return by reference - which of the two is the correct one

    - by eriks
    i have the function: const A& f(...) {...} a. const A a1 = f(..); b. const A &a2 = f(...); which of the is the better one to use? in both cases, if i understand correctly, i prevent the possibility of modifying the returned object. in the first option, the copy constructor of A will be called - am i correct?

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  • C Check Substring of a String C

    - by user69514
    I'm trying to check whether or not the second argument in my program is a substring of the first argument. The problem is that it only work if the substring starts with the same letter of the string. EDIT: It must be done in C, not C++. Sorry #include <stdio.h> #include <string.h> int my_strstr( char const *s, char const *sub ) { char const *ret = sub; while ( ret = strchr( ret, *sub ) ) { if ( strcmp( ++ret, sub+1 ) == 0 ) return 1; } return 0; } int main(int argc, char **argv){ if (argc != 3) { printf ("Usage: check <string one> <string two>\n"); } int result = my_strstr(argv[1], argv[2]); if(result == 1){ printf("%s is a substring of %s\n", argv[2], argv[1]); } else{ printf("%s is not a substring of %s\n", argv[2], argv[1]); } return 0; }

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  • C++ overloading virtual = operator

    - by taz
    Hello, here is the code for my question: class ICommon { public: virtual ICommon& operator=(const ICommon & p)const=0; }; class CSpecial : public ICommon { public: CSpecial& operator=(const CSpecial & cs) { //custom operations return *this; } }; CSpecial obj; Basically: I want the interface ICommon to force it's descendants to implement = operator but don't want to have any typecasts in the implementation. The compiler says "can't instantiate an abstract class. Any help/advice will be appreciated.

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