Evaluation order of new expression?
In the following code sample, do the C++ standard guarantee that '++i' is evaluated after the memory allocation (call to operator new) but before the call to X’s constructor? new X( ++i ) ...
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Why does g++ compile this?
Recently, after being very tired, I wrote the following code: GLfloat* array = new GLfloat(x * y * z); Which, of course should have been: GLfloat* array = new GLfloat[x * y * z]; (Note the square brackets as opposed to the parenthesis.) As far as I know, the first form is not valid, but g++ compiled it. Sure, it spat out a complet...
How to perform fast formatted input from a stream in C++?
The situation is: there is a file with 14 294 508 unsigned integers and 13 994 397 floating-point numbers (need to read doubles). Total file size is ~250 MB. Using std::istream takes ~30sec. Reading the data from file to memory (just copying bytes, without formatted input) is much faster. Is there any way to improve reading speed withou...
Resizing an OpenGL window causes it to fall apart
For some reason when I resize my OpenGL windows, everything falls apart. The image is distorted, the coordinates don't work, and everything simply falls apart. I am sing Glut to set it up. //Code to setup glut glutInitWindowSize(appWidth, appHeight); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA); glutCreateWindow("Test Window"); //In d...
In C++, where in memory are class functions put?
I'm trying to understand what kind of memory hit I'll incur by creating a large array of objects. I know that each object - when created - will be given space in the HEAP for member variables, and I think that all the code for every function that belongs to that type of object exists in the code segment in memory - permanently. Is that...
How to pass references by value in C++?
I'm trying to create am immutable type (class) in C++, I made it so that all methods "aka member functions" don't modify the object and return a new instance instead. I'm running across a bunch of issues, but they all revolve around the reference types in C++. One example is when passing parameters of the same class type by reference:...
C++ templates, undefined reference
I have a function declared like so: template <typename T> T read(); and defined like so: template <typename T> T packetreader::read() { offset += sizeof(T); return *(T*)(buf+offset-sizeof(T)); } However, when I try to use it in my main() function: packetreader reader; reader.read<int>(); I get the following error from ...
Can I use execvp() on a function defined inside my program?
I have a C++ function that I'd like to call using execvp(), due to the way my program is organized. Is this possible? ...
std::vector on VisualStudio2008 appears to be suboptimally implemented - too many copy constructor calls
I've been comparing a STL implementation of a popular XmlRpc library with an implementation that mostly avoids STL. The STL implementation is much slower - I got 47s down to 4.5s. I've diagnosed some of the reasons: it's partly due to std::string being mis-used (e.g. the author should have used "const std::string&" wherever possible - ...
Is C++ a "waste of time"?
I ran into this supposed interview of Bjarne Stroustrup, the inventor of C++. http://artlung.com/smorgasborg/Invention_of_Cplusplus.shtml Stroustrup: Well, it's been long enough, now, and I believe most people have figured out for themselves that C++ is a waste of time but, I must say, it's taken them a lot longer than I thought it ...
How to split a text file into words?
Hello, I am working on a assignment where I am supposed to read a file and count the number of lines and at the same time count the words in it. I tried a combination of getline and strtok inside a while loop, which did not work. file:example.txt (the file to be read). Hi, hello what a pleasant surprise. Welcome to this place. M...
How to Build a custom simple DNS server in C/C++
I need to build a custom simple non-authoritative caching DNS server in C/C++. Any guidance? Links? Samples? Thanks! ...
How to do an efficient priority update in STL priority_queue?
I have a priority_queue of some object: typedef priority_queue<Object> Queue; Queue queue; From time to time, the priority of one of the objects may change - I need to be able to update the priority of that object in the queue in an efficient way. Currently I am using this method which works but seems inefficient: Queue newQueue; whi...
templated typedef ?
I'm using libgc, a garbage collector for C and C++. To make STL containers garbage collectible one must use the gc_allocator. Instead of writing std::vector<MyType> one has to write std::vector<MyType,gc_allocator<MyType> > Could there be a way to define something like template<class T> typedef std::vector<T,gc_allocator<T> ...
Why artificially limit your code to C?
This is prompted by a an answer I gave to a current question which asks about a generics library for C - the questioner specifically states that they do not want to use C++. My question to him and others who insist on using C is why do they do so when: C++ provides the specific features they are asking about Their C compiler is almost ...
Howto Create Map of Vector From Sorted Data
Dear all, I have the following data as input (sorted by first column): foo 1 2 foo 3 3 bar 10 11 I want to create a Map of Vector with first column as key of the map such that we have: foo = {1,2,3,3} bar = {10,11} But why my code below doesn't work as expected? #include <vector> #include <map> #include <iostream> ...
What is the point of adding a return statement at end of a void C/C++ routine?
I see functions/methods with a void return in the signature that have a return statement at the end of the function. What is the reason for this, and does this apply to other languages? For all I know, I can use return if I want to exit anywhere else but the end of the function. A C example: void funtion(void) { int x = 1 + 2; ...
How can you break on handle creation?
I have an application that spawns multiple child processes. Before launching a child, I create stdOut and stdErr handles to a log file (for example, if I am about to launch procA, i create handles to logA.log). I set these handles on the child processes. By looking with ProcExplorer, I can see that each child process has handles to eac...
Detecting the launch of a application
How do I detect with C# on Windows the moment when an external application is being launched? I tried the FilesystemWatcher which doesn't work because the file is not really changing. Also having a timer constantly check all the open processes might be a bit over kill. Is there any other way to do this? If not in C# is it possible to do...
Where does java stderr go?
Hi, I would like to know, where does java stderr standardly go? I know I can change the stderr using System.setErr, which 'Reassigns the "standard" error output stream.', but I dont know, which one is "standard". I would like to specify my question more: I have C++ library that I use in java (jni). The problem is that it appears that ...