c++

How do I get rid of LD_LIBRARY_PATH at run-time?

I am building a C++ application that uses Intel's IPP library. This library is installed by default in /opt and requires you to set LD_LIBRARY_PATH both for compiling and for running your software (if you choose the shared library linking, which I did). I already modified my configure.ac/Makefile.am so that I do not need to set that vari...

C++ return double pointer from function.... what's wrong?

I can't seem to figure out what's wrong with my function.... I need to ask the user for a price and then return it as a double pointer, but I get tons and tons of errors: double* getPrice() { double* price; cout << "Enter Price of CD: " << endl; cin >> &price; return price; } ...

Performance of std::pow - cache misses???

I've been trying to optimize a numeric program of mine, and have run into something of a mystery. I'm looping over code that performs thousands of floating point operations of which 1 call to pow - nevertheless, that call takes 5% of the time... That's not necessarily a critical issue, but it is odd, so I'd like to understand what's ha...

STL Vectors, pointers and classes

Hey! Let's say i have 2 classes: class Class1 { public: std::vector<CustomClass3*> mVec; public: Class1(); ~Class1() { //iterate over all the members of the vector and delete the objects } }; class InitializerClass2 { private: Class1 * mPtrToClass1; public: InitializerClass2(); void Initialize() { mPtrToClass...

Is it ok to pass *this in the constructor in the following example

Class A { A(B& b) : mb(b) { // I will not access anything from B here } B& mb; }; Class B { B(): a(*this) {} A a; } I run into such a situation may times, the contained object needs to use the containers functionality. Having a reference to the container object in the contained object seems to be the best way to do...

Can I use Visual Studio 2010's C++ compiler with Visual Studio 2008's C++ Runtime Library?

I have an application that needs to operate on Windows 2000. I'd also like to use Visual Studio 2010 (mainly because of the change in the definition of the auto keyword). However, I'm in a bit of a bind because I need the app to be able to operate on older OS's, namely: Windows 2000 Windows XP RTM Windows XP SP1 Visual Studio 2010's ...

Help understanding linux/tcp.h

I'm learning to use raw sockets, and im trying to prase out the tcp header data, but i can't seem to figure out what res1, ece, and cwr are. Through my networking book and google i know what the rest stand for, but can't seem to find anything on those three. Below is the tcphdr struct in my includes area. Ive commented the parts a bit ...

c++ library for endian-aware reading of raw file stream metadata?

I've got raw data streams from image files, like: vector<char> rawData(fileSize); ifstream inFile("image.jpg"); inFile.read(&rawData[0]); I want to parse the headers of different image formats for height and width. Is there a portable library that can can read ints, longs, shorts, etc. from the buffer/stream, converting for endianess ...

Returning a dynamically created array from function

I'm trying to create a function that would dynamically allocate an array, sets the values of the elements, and returns the size of the array. The array variable is a pointer that is declared outside the function and passed as a parameter. Here is the code: #include <cstdlib> #include <iostream> using namespace std; int doArray(...

C++ arithmetic with pointers

I am trying to add the following: I have an array of double pointers call A. I have another array of double pointers call it B, and I have an unsigned int call it C. So I want to do: A[i] = B[i] - C; how do I do it? I did: A[i] = &B[i] - C; I don't think I am doing this correctly. Edit: What I want to do is, take the value at in...

When to put C++ function in header file

I've been looking at Boost and various other C++ libraries. The vast majority of Boost is implemented in header files. My question is: under what conditions do you do a header-only implementation (like Boost) or also include a .cpp file? ...

How to redraw the picture while moving windows in openGL?

I have drawn a picture with openGL on my windows. Now whenever I hold the mouse button on the windows and move it, my picture always got distorted. I don't know what function in openGL that can help me redraw the picture while the windows is moved. Anybody could help? I tried this but seems not work: void myDisplay() { ..... } void...

From web programming to embedded systems (Windows CE), best learning path?

(tl;dr: What's the best learning path to go from PHP/Python web development to application development for Windows CE?) I'm a self-taught programmer, and I tend to learn by starting from the goal and researching backwards until I get to a point I know. However, I now have a project involving barcode scanners on a pocket-pc, and I'm at a...

C++ cin keeps skipping.....

I am having problems with my program. WHen I run it, it asks the user for the album, the title, but then it just exits the loop without asking for the price and the sale tax. Any ideas what's going on? This is a sample run Discounts effective for September 15, 2010 Classical 8% Country 4% International 17% Jazz 0% Rock 16% S...

I need help on my C++ assignment using Microsoft Visual C++

Ok, so I don't want you to do my homework for me, but I'm a little lost with this final assignment and need all the help I can get. Learning about programming is tough enough, but doing it online is next to impossible for me... Now, to get to the program, I am going to paste what I have so far. This includes mostly //comments and what I ...

Can you force a crash if a write occurs to a given memory location with finer than page granularity?

I'm writing a program that for performance reasons uses shared memory (sockets and pipes as alternatives have been evaluated, and they are not fast enough for my task, generally speaking any IPC method that involves copies is too slow). In the shared memory region I am writing many structs of a fixed size. There is one program responsibl...

Why is volatile not considered useful in multithreaded C or C++ programming?

As demonstrated in this answer I recently posted, I seem to be confused about the utility (or lack thereof) of volatile in multi-threaded programming contexts. My understanding is this: any time a variable may be changed outside the flow of control of a piece of code accessing it, that variable should be declared to be volatile. Signal...

deleting HBITMAP causes an access violation at runtime.

Hi, I have the following code to take a screenshot of a window, and get the colour of a specific pixel in it: void ProcessScreenshot(HWND hwnd){ HDC WinDC; HDC CopyDC; HBITMAP hBitmap; RECT rt; GetClientRect (hwnd, &rt); WinDC = GetDC (hwnd); CopyDC = CreateCompatibleDC (WinDC); //Create a bitmap compatible with the DC hBitmap = Cre...

Primary language - C++/Qt, C#, Java?

I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, s...

Pipe multiple files (gz) into C program

I've written a C program that works when I pipe data into my program using stdin like: gunzip -c IN.gz|./a.out If I want to run my program on a list of files I can do something like: for i `cat list.txt` do gunzip -c $i |./a.out done But this will start my program 'number of files' times. I'm interested in piping all the files in...