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  • Why do I get corrupt output on my file?

    - by Martin
    I have a simple program which I have compiled in both MinGW and Visual C++ 2008 Express, and both give an output file larger than 88200. When I set s = 0, both programs work as expected. What am I doing wrong? #include <fstream> using namespace std; int main(int argc, char *argv[]) { int i; short s; fstream f; f.open("test.raw", ios_base::out); for(i = 0; i < 44100; i++) { s = i & 0xFFFF; // PROBLEM? f.write(reinterpret_cast<const char *>(&s), sizeof(s)); } f.close(); return 0; }

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  • C++, create an instance from a static method

    - by Manux
    Hello, let's say I want my users to use only one class, say SpecialData. Now, this data class would have many methods, and depending on the type of data, the methods do different things, internally, but return externally similar results. Therefore my wanting to have one "public" class and other "private", child classes that would change the behavior of methods, etc... It would be amazingly more simple for some types of data that need to be built to do something like this: SpecialData& sm = SpecialData::new_supermatrix(); and new_supermatrix() would return a SuperMatrix instance, which inherits from most behaviors of SpecialData. my header: static SpecialData& new_supermatrix(); my cpp: SpecialData& SpecialData::new_supermatrix()(){ return SuperMatrix(MATRIX_DEFAULT_MAGNITUDE,1000,1239,FLOAT32,etc...); } The problem is, I get this error, which is probably logical due to the circumstances: invalid initialization of non-const reference of type ‘SpecialData&’ from a temporary of type ‘SpecialData’ So, any ideas?

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  • hierarchical html listbox with mimicking file explorer level folding

    - by collapsar
    hello everybody, i'm looking for a technique to adapt a html listbox to hierarchical content with an unlimited number of levels ( const 1 would be sufficient ). hierarchy levels should be collapsible as in the usual file explorer views. the html listbox behaviour should be preserved / mimicked as comprehensively as possible. do you have a hint on where to find or how to implement this ? jquery solutions are fine. firefox 3.5+, ie 8+, safari 5 must be supported; opera 11, chrome 9 would be nice. as far as i understand the issue, listbox contents are rendered inside their own browser window sporting none of the standard window adornments. a hint on how to obtain a handle on this window in js would be a sufficient starting point, as well as correcting me in case i misconceived the browser behaviour. thanks in advance for your efforts, best regards, carsten

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  • Why we used double pointer in objective-C or C language?

    - by Rajendra Bhole
    Hi, I confused when i want to take single pointer and when should i take double pointer? In following structure what exactly did? struct objc_class { Class isa; Class super_class; const char *name; long version; long info; long instance_size; struct objc_ivar_list *ivars; struct objc_method_list **methodLists; struct objc_cache *cache; struct objc_protocol_list *protocols; }; Why we use the "**methodLists" double pointer?

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  • compare function for dates

    - by Chris
    I have struct as: struct stored { char *dates; // 12/May/2010, 10/Jun/2010 etc.. int ctr; }; // const struct stored structs[] = {{"12/May/2010", 1}, {"12/May/2011", 1}, {"21/May/2009", 4}, {"12/May/2011", 3}, {"10/May/2011", 8}, {"12/May/2011", 4 }}; What I want to do is to sort struct 'stored' by stored.dates. qsort(structs, 9, sizeof(struct stored*), sortdates); // sortdates function I'm not quite sure what would be a good way to sort those days? Compare them as c-strings?

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  • How to look up an NHibernate entity's table mapping from the type of the entity?

    - by snicker
    Once I've mapped my domain in NHibernate, how can I reverse lookup those mappings somewhere else in my code? Example: The entity Pony is mapped to a table named "AAZF1203" for some reason. (Stupid legacy database table names!) I want to find out that table name from the NH mappings using only the typeof(Pony) because I have to write a query elsewhere. How can I make the following test pass? private const string LegacyPonyTableName = "AAZF1203"; [Test] public void MakeSureThatThePonyEntityIsMappedToCorrectTable() { string ponyTable = GetNHibernateTableMappingFor(typeof(Pony)); Assert.AreEqual(LegacyPonyTableName, ponyTable); } In other words, what does the GetNHibernateTableMappingFor(Type t) need to look like?

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  • C++ template parameter/class ambiguity

    - by aaa
    hello. while testing with different version of g++, the following problem came up template<class bra> struct Transform<bra, void> : kernel::Eri::Transform::bra { static const size_t ni = bra::A::size; bra::A is interpreted as kernel::Eri::Transform::bra::A, rather than template argument by g++ 4.1.2. on the other hand, g++ 4.3 gets it right. what should be correct behavior according to standard? Meanwhile, I refactor slightly to make problem go away.

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  • Boost::asio bug in MSVC10 - Failing BOOST_WORKAROUND in ~buffer_debug_check() in buffer.hpp

    - by shaz
    A straight compilation of example http://www.boost.org/doc/libs/1_43_0/doc/html/boost_asio/tutorial/tutdaytime3/src.html results in a runtime null pointer exception. Stack trace points to the buffer_debug_check destructor which contains this comment: // MSVC's string iterator checking may crash in a std::string::iterator // object's destructor when the iterator points to an already-destroyed // std::string object, unless the iterator is cleared first. The test #if BOOST_WORKAROUND(BOOST_MSVC, = 1400) succeeds in MSVC10 and (but) results in a null pointer exception in c:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\xutility line 123 _Iterator_base12& operator=(const _Iterator_base12& _Right) { // assign an iterator if (_Myproxy != _Right._Myproxy) _Adopt(_Right._Myproxy->_Mycont); return (*this); } _Right._Myproxy is NULL

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  • Where does output of print in kernel go?

    - by apoorv020
    I am debugging a driver for linux (specifically ubuntu server 9.04), and there are several printf statements in the code. Where can I view the output of these statements? EDIT1: What i'm trying to do is write to kernel using the proc file-system. The print code is static int proc_fractel_config_write(struct file *file, const char *argbuf, unsigned long count, void *data) { printk(KERN_DEBUG "writing fractel config\n"); ... In kern.log when I see the following message when i try to overwrite the file /proc/net/madwifi/ath1/fractel_config (with varying time of course). [ 8671.924873] proc write [ 8671.924919] Any explainations?

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  • VBScript Permission Denied on CopyFile

    - by Chris
    I'm running a VBScript in SQL Agent but I get a 'Permission Denied' on line 34 (the first copy attempt). I've run this script outside SQL Agent with no problems Function Main() Const SourceDrive As String = "X:\" Dim fso Dim Today Dim FileName Dim FromFile Dim FromDrive Dim ArchivePath Set fso = CreateObject("Scripting.FileSystemObject") Today = Format(Now, "yyyyMMdd") 'To add more sources just add them to the array list Dim Sources() As Variant Sources() = Array("Item1", _ "Item2") 'To add more targets just add them to the array list Dim Targets() As Variant Targets() = Array("C:\Users\myalias\Desktop\MyToFolder", _ "C:\Users\myalias\Desktop\MyToFolder2") For i = 0 To UBound(Sources) FileName = "WebSurveyAlertCallbacks_" & Sources(i) & "_" & Today & ".xls" FromDrive = fso.BuildPath(SourceDrive, Sources(i)) FromFile = fso.BuildPath(FromDrive, FileName) ArchivePath = fso.BuildPath(FromDrive, "Archive") If fso.FileExists(FromFile) Then For t = 0 To UBound(Targets) fso.CopyFile FromFile, fso.BuildPath(Targets(t), FileName), True Next fso.CopyFile FromFile, fso.BuildPath(ArchivePath, FileName), True fso.DeleteFile FromFile End If Next Set fso = Nothing Main = DTSTaskExecResult_Success End Function

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  • Better way of enforcing this template?

    - by Dennis Ritchie
    Currently, I have a function template like this that converts a vector into a string (just a natural string, separating the elements with a comma): //the type T must be passable into std::to_string template<typename T> std::string vec_to_str(const std::vector<T> &vec); As you can see, this is only meant for vectors whose elements can be passed into the built-in std::to_string function (such as int, double, etc.) Is it considered a good practice to document with comments the allowed T? If not, what should I do? Is it possible to enforce this in a better way?

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  • GCC fatal error: stdio.h: No such file or directory

    - by user2615799
    I'm trying to compile a program in C on OS X 10.9 with GCC 4.9 (experimental). For some reason, I'm getting the following error at compile time: gcc: fatal error: stdio.h: No such file or directory I then tried a simple Hello World program: #include <stdio.h> int main(int *argc, const char *argv[]) { printf("Hello, world!"); return 0; } Again, upon running gcc -o ~/hello ~/hello.c, I got the same error. I'm using an experimental version of gcc, but it seems implausible that there would be a release which generated errors upon importing stdio. What could be causing this issue, and how can it be fixed?

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  • c++/cli pass (managed) delegate to unmanaged code

    - by Ron Klein
    How do I pass a function pointer from managed C++ (C++/CLI) to an unmanaged method? I read a few articles, like this one from MSDN, but it describes two different assemblies, while I want only one. Here is my code: 1) Header (MyInterop.ManagedCppLib.h): #pragma once using namespace System; namespace MyInterop { namespace ManagedCppLib { public ref class MyManagedClass { public: void DoSomething(); }; }} 2) CPP Code (MyInterop.ManagedCppLib.cpp) #include "stdafx.h" #include "MyInterop.ManagedCppLib.h" #pragma unmanaged void UnmanagedMethod(int a, int b, void (*sum)(const int)) { int result = a + b; sum(result); } #pragma managed void MyInterop::ManagedCppLib::MyManagedClass::DoSomething() { System::Console::WriteLine("hello from managed C++"); UnmanagedMethod(3, 7, /* ANY IDEA??? */); } I tried creating my managed delegate and then I tried to use Marshal::GetFunctionPointerForDelegate method, but I couldn't compile.

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  • int[] to string c#

    - by Robin Webdev
    Hi I'm developing an client application in C# and the server is written in c++ the server uses: inline void StrToInts(int *pInts, int Num, const char *pStr) { int Index = 0; while(Num) { char aBuf[4] = {0,0,0,0}; for(int c = 0; c < 4 && pStr[Index]; c++, Index++) aBuf[c] = pStr[Index]; *pInts = ((aBuf[0]+128)<<24)|((aBuf[1]+128)<<16)|((aBuf[2]+128)<<8)|(aBuf[3]+128); pInts++; Num--; } // null terminate pInts[-1] &= 0xffffff00; } to convert an string to int[] in my c# client i recieve: int[4] { -14240, -12938, -16988, -8832 } How do I convert the array back to an string? I don't want to use unsafe code (e.g. pointers) Any of my tries resulted in unreadable strings.

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  • strcat() won't exit

    - by Tristan Sebens
    I'm trying to implement a very basic server in C, one part of which is constructing HTTP headers. To do this I have written a class called header_builder, which basically constructs the headers for me. One of the most basic methods of this class is append_header_line, shown below: void append_header_line( const char *line, char *hdr ) { printf("Adding header line\n"); strcat( hdr, line ); printf("Line added. Adding ending.\n"); strcat( hdr, "\r\n" ); printf("Success\n"); } All it's supposed to do is tack the "line" parameter onto the end of the "hdr" parameter, and then add "\r\n" to the end of it all. The problem is that the first strcat call never exits. When I run this code, all it does is say: Adding header line Which means that the following lines never execute, and I can't figure out why. Any thoughts?

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  • std::string constructor corrupts pointer

    - by computergeek6
    I have an Entity class, which contains 3 pointers: m_rigidBody, m_entity, and m_parent. Somewhere in Entity::setModel(std::string model), it's crashing. Apparently, this is caused by bad data in m_entity. The weird thing is that I nulled it in the constructor and haven't touched it since then. I debugged it and put a watchpoint on it, and it comes up that the m_entity member is being changed in the constructor for std::string that's being called while converting a const char* into an std::string for the setModel call. I'm running on a Mac, if that helps (I think I remember some problem with std::string on the Mac). Any ideas about what's going on?

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  • Boost singleton and undefined reference

    - by Ockonal
    Hello, I globally use singleton pattern in my project. To make it easier - boost::singleton. Current project uses Ogre3d library for rendering. Here is some class: class GraphicSystem : public singleton<GraphicSystem> { private: Ogre::RenderWindow *mWindow; public: Ogre::RenderWindow *getWindow() const { return mWindow; } }; In GraphicSystem constructor I fill the mWindow value: mWindow = mRoot->createRenderWindow(...); I cheked it, everything makes normally. So, now I have to use handler for the window in input system (to get window handle). Somewhere else in another class: Ogre::RenderWindow *temp = GraphicSystem::get_mutable_instance().getWindow(); GraphicSystem::get_mutable_instance().getWindow()->getCustomAttribute("WINDOW", &mWindowHandle); temp is 0x00, and there is segfault at last line (getting custon attribute). I can't understand, why does singleton returns undefined pointer for the window. All another singleton-based classes work well.

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  • Does C++ have a static polymorphism implementation of interface that does not use vtable?

    - by gilbertc
    Does C++ have a proper implementation of interface that does not use vtable? for example class BaseInterface{ public: virtual void func() const = 0; } class BaseInterfaceImpl:public BaseInterface{ public: void func(){ std::cout<<"called."<<endl; } } BaseInterface* obj = new BaseInterfaceImpl(); obj->func(); the call to func at the last line goes to vtable to find the func ptr of BaseInterfaceImpl::func, but is there any C++ way to do that directly as the BaseInterfaceImpl is not subclassed from any other class besides the pure interface class BaseInterface? Thanks. Gil.

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  • typedef resolution rule

    - by kumar_m_kiran
    Hi All, Can you Please tell me the resolution rule involved in resolving the meaning of the variable in a typedef. Any link related to the same will be very useful. Example #typedef string* pstring; const pstring parr; Here confusion arises whether const'ness is for pointer or the content. Now based on what thumb rule do can we start resolving the above interpretation of the pstring?. Smilarly, If I have a very complex typedef'ed variable, like #typedef void (func*)()(int), I should be able to resolve it using the thumb rule. Thanks in advance for your suggestions

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  • Is there a way to serialize automatically enums as int?

    - by FireAphis
    Hello, Is there a way to serialize enums automatically as int? Every time I define a new enum and write std::stringstream stream; stream << myenum1; stream >> myenum2; the compiler complains that the operators << and are not defined. Do you know a way to tell the compiler to treat enums as plain int's? What makes the problem harder is that, actually, the serialization is inside a template. Something like this: template <typename T> void serialize(const T& value) { std::stringstream stream; stream << value; } So I cannot add any casts :( Maybe I can specialize it somehow? Thank you.

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  • How to use #ifdef entities as part of functions in header files

    - by Crazyjavahacking
    I would like to ask if it is possible to use the entities defined in #ifdef block in header files. To be clear, I have following code: #ifdef #include <winsock2.h> #define SOCKET_HANDLE SOCKET #define CONNECTION_HANDLE SOCKET #endif SOCKET_HANDLE createServerSocket(const char* hostAddress, short port); I am Java developer and this seems completely fine for me. However compiler has a problem with this. Can you explain why is that code a problem? Also how can I force to compile it. (The idea is to have generic interface and conditional compilation to determine real types according to running platform at compile time.) Thanks

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  • C++ cin returns 0 for integer no matter what the user inputs

    - by kevin dappah
    No matter the cin it continues to to output 0 for score. Why is that? I tried returning the "return 0;" but still no go :/ #include "stdafx.h" #include <iostream> using namespace std; // Variables int enemiesKilled; const int KILLS = 150; int score = enemiesKilled * KILLS; int main() { cout << "How many enemies did you kill?" << endl; cin >> enemiesKilled; cout << "Your score: " << score << endl; return 0; }

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  • QMap inheritance with QMapIterator

    - by gregseth
    Hi, I made a personnal class which inherits QMap: class CfgMgr : public QMap<QString, CfgSet*> {...} I'm trying to iterate over all its elements like that: CfgMgr* m_pDefaults = new CfgMgr; // .../... QMapIterator<QString, CfgSet*> ics(*m_pDefaults); while (ics.hasNext()) { // doing my stuff } And I get the compile error: Can't convert parameter 1 from 'CfgMgr' to 'const QMap< Key,T &' with [ Key=QString, T=CfgSet * ] I tried with a dynamic_cast: QMapIterator<QString, CfgSet*> ics( *dynamic_cast< QMap<QString,CfgSet*>* >(m_pDefaults) ); it compiles, but always returns NULL. What's wrong? How can I solve this?

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  • Quick, Beginner C++ Overloading Question - Getting the compiler to perceive << is defined for a spec

    - by Francisco P.
    Hello everyone. I edited a post of mine so I coul I overloaded << for a class, Score (defined in score.h), in score.cpp. ostream& operator<< (ostream & os, const Score & right) { os << right.getPoints() << " " << right.scoreGetName(); return os; } (getPoints fetches an int attribute, getName a string one) I get this compiling error for a test in main(), contained in main.cpp binary '<<' : no operator found which takes a right-hand operand of type 'Score' (or there is no acceptable conversion) How come the compiler doesn't 'recognize' that overload as valid? (includes are proper) Thanks for your time.

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  • extraneous calls to copy-constructor and destructor

    - by eSKay
    [This question is a follow up to this question] class A { public: A() {cout<<"A Construction" <<endl;} A(A const& a){cout<<"A Copy Construction"<<endl;} ~A() {cout<<"A Destruction" <<endl;} }; int main() { { vector<A> t; t.push_back(A()); t.push_back(A()); // once more } } The output is: A Construction // 1 A Copy Construction // 1 A Destruction // 1 A Construction // 2 A Copy Construction // 2 A Copy Construction // WHY THIS? A Destruction // 2 A Destruction // deleting element from t A Destruction // deleting element from t A Destruction // WHY THIS?

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