c++

give feedback on this pointer program

This is relatively simple program. But I want to get some feedback about how I can improve this program (if any), for example, unnecessary statements? #include<iostream> #include<fstream> using namespace std; double Average(double*,int); int main() { ifstream inFile("data2.txt"); const int SIZE = 4; double *array = new ...

segfault during __cxa_allocate_exception in SWIG wrapped library

While developing a SWIG wrapped C++ library for Ruby, we came across an unexplained crash during exception handling inside the C++ code. I'm not sure of the specific circumstances to recreate the issue, but it happened first during a call to std::uncaught_exception, then after a some code changes, moved to __cxa_allocate_exception durin...

compiling a c++ program including mysql

I'm new to gcc, and trying to compile a c++ program which includes mysql.h using the command: g++ -o test test.cpp -L/usr/include/mysql -lmysqlclient -I/usr/include/mysql It works without issue, but I was wondering if someone could explain the arguments to me. I don't like using commands I don't understand. Thanks ...

struct size is different from typedef version?

I have the following struct declaration and typedef in my code: struct blockHeaderStruct { bool allocated; unsigned int length; }; typedef struct blockHeaderStruct blockHeader; When I do sizeof(blockheader), I get the value of 4 bytes back, but when I do sizeof(blockHeaderStruct), I get 8 bytes. Why is this happening? Why am ...

Template Child Class Overriding a Parent Class's Virtual Function

The below code compiles with gcc v4.3.3 and the templated child class seems to be overriding a virtual function in the parent, but doesn't that break the rule that you cannot have a virtual template function? Or is something else happening that I don't understand? class BaseClass { public: virtual void Func(int var) { std::cout...

What are pointers to class members used for?

I have read about pointers to class members, but I have never seen them being used in any practical applications. Can someone explain what are the use cases of such pointers? Is it really necessary to have such pointers? Eg. class abc { public: int a; abc(int val) { a = val; } }; int main() { int abc::*data; abc obj(5)...

Can I use C++/CLI (.NET Winforms/WPF ) to provide GUI for app written in native C & C++

Hello, I've an app written C & C++. Now, I need to provide a GUI for this app. MFC is the best option for me. But I'm not familiar with MFC. So can I use .NET to build GUI for this? If so, How? Please be clear. If I can use .NET I guess I can use WPF too right? ...

Error on writing data to DVD

Hi, From past 1 week i stuck on this please help me i am attaching code. bool DVDBurner::Burner() { m_hResult = CoCreateInstance(__uuidof(MsftDiscFormat2Data), NULL, CLSCTX_INPROC_SERVER, __uuidof(IDiscFormat2Data), (void**)&m_discFormatData); if (!SUCCEEDED(m_hResult)) { qDebug()<<"Unable to Initialize IDiscFormat2Data "; return false...

Difference in behaviour (GCC and Visual C++)

Consider the following code. #include <stdio.h> #include <vector> #include <iostream> struct XYZ { int X,Y,Z; }; std::vector<XYZ> A; int rec(int idx) { int i = A.size(); A.push_back(XYZ()); if (idx >= 5) return i; A[i].X = rec(idx+1); return i; } int main(){ A.clear(); rec(0); puts("FINISH!"); } I coul...

Artifacts when trying to draw background grid without anti-aliasing in a QGraphicsScene

Hi folks, I'm trying to draw a background grid in the drawBackground() function of my QGraphicsScene subclass: void Scene::drawBackground(QPainter *painter, const QRectF &rect) { const int gridSize = 50; const int realLeft = static_cast<int>(std::floor(rect.left())); const int realRight = static_cast<int>(std::ceil(rect.ri...

template; Point<2, double>; Point<3, double>

Hi, I want to create my own Point struct it is only for purposes of learning C++. I have the following code: template <int dims, typename T> struct Point { T X[dims]; Point(){} Point( T X0, T X1 ) { X[0] = X0; X[1] = X1; } Point( T X0, T X1, T X2 ) { X[0] = X0; X[1] = X1; X[2...

Scaling a CBitmap - what am I doing wrong?

I've written the following code, which attempts to take a 32x32 bitmap (loaded through MFC's Resource system) and turn it into a 16x16 bitmap, so they can be used as the big and small CImageLists for a CListCtrl. However, when I open the CListCtrl, all the icons are black (in both small and large view). Before I started playing with resi...

behaviour of the implicit copy constructor / assignment operator

Hello, I have a question regarding the C++ Standard. Suppose you have a base class with user defined copy constructor and assignment operator. The derived class uses the implicit one generated by the compiler. Does copying / assignment of the derived class call the user defined copy constructor / assignment operator? Or do you need to...

C++ stack in Objective-C++

I'd like to use a C++ stack type in Objective-C, but I'm running into some issues. Here's a sample of what I would like to do: #import <stack> #import <UIKit/UIKit.h> @interface A : NSObject { stack<SEL> selectorStack; } @end Unfortunately, this doesn't compile. After messing around with the code for a while and trying differe...

can i use dtsearch in C++ under linux, if yes what APIshould i use?

Hello, I want to use dtsearch in my desktop application written in C++ and Gtkmm. Can i have any API or link to the API to do my thing. Thanks and Regards Owais Masood ...

How to create GIF file from other format file in C++

I want to create 2 bits per pixel GIF files in VC environment from a TIFF file. Is there any free library or maybe source that could help me? Or how can I do it myself? ...

How did it happen that "static" denotes a function/variable without external linkage in C and C++?

In C static can mean either a local variable or a global function/variable without external linkage. In C++ it can also mean a per-class member variable or member function. Is there any reference to how it happened that the static keyword that seems totally irrelevant to lack of external linkage is used to denote lack of external linkag...

overloading new/delete problem

This is my scenario, Im trying to overload new and delete globally. I have written my allocator class in a file called allocator.h. And what I am trying to achieve is that if a file is including this header file, my version of new and delete should be used. So in a header file "allocator.h" i have declared the two functions extern voi...

Constant member

I have structure defined in some header (D3DXVECTOR3) How can I declare: static member in the class of that type and initialize it? maybe constant member of that type and init it? when i use some constructor i get error only integral can be initialized. ...

Accessing "Mapi32.dll" with C#. [not solved]

Hello, I am using VS 2008 C# Windows Application. I have this DLL Import I am trying to use. [DllImport("Mapi32.dll", PreserveSig = true)] private static extern void WrapCompressedRTFStream( [MarshalAs(UnmanagedType.Interface)] UCOMIStream lpCompressedRTFStream, uint ulflags, [MarshalAs(UnmanagedType.Interface)] out UCOMIStream lpUnco...