c++

Is the C++ compiler optimizer allowed to break my destructor ability to be called multiple times?

We once had an interview with a very experienced C++ developer who couldn't answer the following question: is it necessary to call the base class destructor from the derived class destructor in C++? Obviously the answer is no, C++ will call the base class destructor automagically anyway. But what if we attempt to do the call? As I see i...

When I overload the assignment operator for my simple class array, I get the wrong answer I expect

//output is "01234 00000" but the output should be or what I want it to be is // "01234 01234" because of the assignment overloaded operator #include <iostream> using namespace std; class IntArray { public: IntArray() : size(10), used(0) { a= new int[10]; } IntArray(int s) : size(s), used(0) { a= new int[s]; } int& operator[]( int...

CInternetSession::OpenURL exception if headers are defined. Works fine if not. Why?

Trying to log the application version details in our weblogs using the headers: Should be a one liner..but for some reason whenever I specify anything but NULL for the headers it causes an exception (InternetOpenUrl() call returns NULL) - anyone able to explain why? CInternetSession internet; CHttpFile * pHttpFile; CString header...

decltype, result_of, or typeof?

I have: class A { public: B toCPD() const; And: template<typename T> class Ev { public: typedef result_of(T::toCPD()) D; After instantiating Ev<A>, the compiler says: meta.h:12: error: 'T::toCPD' is not a type neither decltype nor typeof work either. ...

How to force Mac window to foreground?

How can I programmatically force a mac window to be the front window? I have the window handle, and want to ensure that my window is displayed above all other windows. I can use both Carbon & Cocoa for this. ...

C++ performance, optimizing compiler, empty function in .cpp

I've a very basic class, name it Basic, used in nearly all other files in a bigger project. In some cases, there needs to be debug output, but in release mode, this should not be enabled and be a NOOP. Currently there is a define in the header, which switches a makro on or off, depending on the setting. So this is definetely a NOOP, whe...

Arrays of pointers to arrays?

I'm using a library which for one certain feature involves variables like so: extern const u8 foo[]; extern const u8 bar[]; I am not allowed to rename these variables in any way. However, I like to be able to access these variables through an array (or other similar method) so that I do not need to continually hardcode new instances ...

Storing images and pointers in OpenCV

I have a loop which goes through a video with some processing/calculations of the images. I want to save the image in the loop with the highest value from the processing, but I'm struggling a bit with storing the image temporally while the loop finishes. The images/frames are initialized like this IplImage* frame = 0; IplImage* maxfram...

How to copy files in Visual C++?

I am using Visual C++. How to copy the content of this file to another file? UINT32 writeToLog(wstring log) { wfstream file1 (LOG_FILE_NAME, ios_base::out); file1 << log; file1.close(); // want to copy file1 to file2 return 0; } ...

boost::asio::local::stream_protocol::iostream does not work?

Referencing an old (from 2008) discussion: There is a compile error when trying to use boost::asio::local::stream_protocol::iostream There was no solution on the discussion forum and I've run into the same problem, it seems. Has there been a fix or solution for the compile error? How can I use boost::asio::local::stream_protocol::iost...

Why does double dispatch not work in C++?

#include<iostream.h> #include<conio.h> using namespace std; class SpaceShip {}; class GiantSpaceShip : public SpaceShip {}; class Asteroid { public: virtual void CollideWith(SpaceShip *) { cout << "Asteroid hit a SpaceShip" << endl; } virtual void CollideWith(GiantSpaceShip *) { cout << "Asteroid hit a GiantSpaceShip" <<...

SHCreateStreamOnFileEx linker error

Hi, I am getting linker error while working on SHCreateStreamOnFileEx. Please help me to find out the problem. IStream* replace::GetStream() { LPCWSTR pszFile=L"D:\\Test\\output.txt"; IStream* dataStream = NULL; if (dataStream == NULL) { SHCreateStreamOnFileEx(pszFile, STGM_READ|STGM_SHARE_DENY_NONE|STGM_DELETEONRELEASE, ...

Link error (LNK2019) when including other projects in Visual Studio 2005

I am trying to work with several projects on visual studio 2005. I have one project that depends on two others. I have included those two project in the first project solution, and set the dependencies correctly. I get this error when linking the project: 1>server_controller.obj : error LNK2019: unresolved external symbol "public: __t...

Library/component to visualize modeling environment?

Hi I am looking for a COTS library to visualize a custom modeling language to be used for the configuration of a dynamic system. The non-programmer users need to drag, drop some blocks with ports, connect them using specific connectors like using Matlab Simulink. The library might include only widgets or widgets plus some framework for ...

c++ tables of unions and structures

I was told to write a program, that creates a union and structure, then creates two-element arrays of unions and structures and fills their fields. I have created a union and a structure, but how to fill their fields in arrays ? #include <iostream> #include <stdlib.h> #include <stdio.h> using namespace std; union complex; union comple...

how to traverse a file in python and c++ in backward way? And also store data in backward (bottom to top) way?

Suppose i want to store 3 lines in a file both in python and C++ . I want to store it like this aaa bbb ccc .. But i am giving ccc input first then bbb then aaa. How will I traverse the file from bottom to top and also store from bottom to top/? ...

creating an array which can hold objects of different classes in C++

Hi, How can i create an array which can hold objects of different classes in C++. ...

Object Deletion: use parent or not

Which one do you prefer to delete objects? Especially in QT, but other practices are also welcome. These two alternatives seem same to me, are they? 1.Bound to another class, and destroy when it is destroyed. SomeClass::SomeClass{ socket_ = new QTcpSocket(this); } or 2.Destroy in the destructor of class SomeClass::SomeClass{ soc...

Adding a transparent bitmap to a windows button

It's a while since I've done this, but I'm trying to add a custom button graphic to a windows button, with some transparent areas. I've tried various schemes but can't seem to get the transparent areas to show. Here's my code: hbmpUpDisabled = LoadImage(instance,MAKEINTRESOURCE(IDB_UPARROWDISABLED), IMAGE_BITMAP, 0, 0, LR_DEFAULTSIZE ...

Best protocol for client/server communication, from PHP/Perl to C++/Qt4

I'm the author of an Open Source kiosk management system, Libki. The current version, though functional, was very much a learning experience for me. I'm working on a complete rewrite and am having a hard time deciding what protocol to use. The server will be written in PHP or Perl. Most likely PHP because I need to support some uncommon...