c++

How to use a object whose copy constructor and copy assignment is private?

In reading TCPL, I got a problem, as the title refered, and then 'private' class is: class Unique_handle { private: Unique_handle& operator=(const Unique_handle &rhs); Unique_handle(const Unique_handle &rhs); public: //... }; the using code is: struct Y { //... Unique_handle obj; }; and I want to execute such op...

How to use objects that got the private copy-constructor and assignment-constructor?

Possible Duplicate: How to use a object whose copy constructor and copy assignment is private? In reading TCPL, I got a problem, as the title refered, and then 'private' class is: class Unique_handle { private: Unique_handle& operator=(const Unique_handle &rhs); Unique_handle(const Unique_handle &rhs); public:...

Purpose of Header guards

In C++ what is the purpose of header guard in C++ program. From net i found that is for preventing including files again and again but how do header guard guarantee this. ...

MultiOS "Jet Database" for C++/Qt?

Hopefully I can articulate this well: I'm porting an application I made years ago from VB6 (I know, I know!) to C++/Qt. In my original application, one thing I liked was that I didn't need an actual SQL server running, I could just use MS Access .mdb files. I was wondering if something similar exists for Qt that will work on multiple OSe...

Why C/C++ have memory issue?

I have read lots of programmers saying and writing when programming in C/C++ there are lots of issue related to memory. I am planning to learn to program in C/C++. I have beginner knowledge of C/C++ and I want to see some short sample why C/C++ can have issues with memory management. Please Provide some samples. ...

How to test if a string has a certain unicode char?

Supose you have a command line executable that receives arguments. This executalbe is widechar ready and you want to test if one of this arguments starts with an HYPHEN case in which its an option: command -o foo how you could test it inside your code if you don't know the charset been used by the host? Should be not possible to a give...

Boost threading/mutexs, why does this work?

Code: #include <iostream> #include "stdafx.h" #include <boost/thread.hpp> #include <boost/thread/mutex.hpp> using namespace std; boost::mutex mut; double results[10]; void doubler(int x) { //boost::mutex::scoped_lock lck(mut); results[x] = x*2; } int _tmain(int argc, _TCHAR* argv[]) { boost::thread_group thds; for (int x = 10; x>0...

How can I use STL sort in c++ to sort some values in the class?

I have a class named Graph, in this class I have a member named V, it is a vector. I have a struct named Edge, and a list of Edges. like below: struct Edge{ int u; int v; Edge(int u,int v){ this->u=u; this->v=v; } }; struct Vertex{ int d; int f; . . . } class Graph{ vector < Vertex > V; . . . int edgeCmp(Edge* ...

Print layout of C++ object with g++ compiler

Is there a way to print the layout of a C++ object using the g++ compiler or any other means. A simplified example (assuming int takes 4 bytes) class A{ int a; }; class B:public A{ int b; } so the output would be A- 0 4 + a + B- 0 4 8 + A.a + b + It would be useful to understand the layout of objects (...

Static Typing and Writing a Simple Matrix Library

Aye it's been done a million times before, but damnit I want to do it again. I'm writing a simple Matrix Library for C++ with the intention of doing it right. I've come across something that's fairly obvious in mathematics, but not so obvious to a strongly typed system -- the fact that a 1x1 matrix is just a number. To avoid this, I s...

How do you use C++0x raw strings with GCC 4.5?

This page says that GCC 4.5 has C++ raw string literals: http://gcc.gnu.org/projects/cxx0x.html But when I try to use the syntax from this page: http://www2.research.att.com/~bs/C++0xFAQ.html#raw-strings #include <iostream> #include <string> using namespace std; int main() { string s = R"[\w\\\w]"; } I get this error: /opt/...

QScrollArea widget content promoted to QWidget

Hi folks, First of all, thanks for you time reading my question. I created my own Qt Widget (parent of QWidget) and has a QImage "inside" to manipulate images. The problem I have is the following: when I promote the content of a QScrollArea (QDesigner) to my widget, the scroll features doesn't works; I haven't any scroll bar or I can't...

Parametrised and Conversion Constructors

Is there any difference between parametrised constructor and conversion constructor. If so what is it? ...

Need to make a simple C++ project with Sqlite

I just research the sqlite3! i dont know the way to connect database - it's maked by sqlite - to C++ project! Could you help me create a example, please? Thanks so much everybody! ...

Achieving C# "readonly" behavior in C++

Hi guys, this is my first question on stack overflow, so be gentle. Let me first explain the exact behavior I would like to see. If you are familiar with C# then you know that declaring a variable as "readonly" allows a programmer to assign some value to that variable exactly once. Further attempts to modify the variable will result in ...

How to get the Drive letter and Mount Path - MSDN

Hello all, I get the devices list from the system using SetupDiGetClassDevs Function - MSDN. Also i can able to get the vendor id and product id from the devices. But i cant able to get the drive letter and the mount path For Example if i plug the usb drive means , i have to get the drive letter like "G:/" Please help me to get the ...

how to convert utf-8 to ASCII in c++?

i am getting response from server in utf-8 but not able to read that. how to convert utf-8 to ASCII in c++? ...

Ogre3D strange behavior

I compiled Ogre on my Lubuntu 10.04 with LXDE environment, and when I try to start ./SampleBrowser_d from /bin i have incomplete window...it haven't got background, I can't click on accept and i can't choose OpenGL from avaible list..Anybody know what's it and how fix it ? Here's some screenshots: link text Any suggestions? ...

How to get only USB devices not all the devices in the system

Grretings to all, I get devices list from the system. but i am not sure that if i want to get only the usb devices currently in the system means , What class i must specify in the below code ( DWORD Flags ) hDevInfo = SetupDiGetClassDevs(&GUID_DEVINTERFACE_USB_DEVICE, 0, // Enumerator ...

base destructor called twice after derived object?

hey there, why is the base destructor called twice at the end of this program? #include <iostream> using namespace std; class B{ public: B(){ cout << "BC" << endl; x = 0; } virtual ~B(){ cout << "BD" << endl; } void f(){ cout << "BF" << endl; } virtual void g(){ cout << "BG" << endl; } private: int x; ...