Here's the thing: In my Qt4.6-Project, I use a SQLite-Database. This database shouldn't be unencrypted on my harddrive. So I want, that on every start of my program, the user gets asked to enter a password to decrypt the database. Of course the database never should appear "in clear" (not encrypted) on my harddrive. So is there any possi...
I would like to have declaration like this: void Date::get_days_name(const Date& = this) which I would understand that if no argument is provided use this object as an argument. For some reason in VS I'm getting err msg: 'Error 1 error C2355: 'this' : can only be referenced inside non-static member ' Any idea what I'm doing w...
I would like to be able to write: cout << enumalpha << Monday; and get printed on console: Monday P.S. Monday is an enum type. ...
can a function return more than one value? Edit Except return by reference. ...
I have a pet project with which I experiment with new features of the upcoming C++0x standard. While I have experience with C, I'm fairly new to C++. To train myself into best practices, (besides reading a lot), I have enabled some strict compiler parameters (using GCC 4.4.1): -std=c++0x -Werror -Wall -Winline -Weffc++ -pedantic-errors ...
I have a C++ program which, during execution, will allocate about 3-8Gb of memory to store a hash table (I use tr1/unordered_map) and various other data structures. However, at the end of execution, there will be a long pause before returning to shell. For example, at the very end of my main function I have std::cout << "End of execut...
Hi all. In my code i tried to connect signal from QTrayIcon object and my form in such way: connect(m_trayIcon, SIGNAL(activated(QSystemTrayIcon::ActivationReason)), this, SLOT(iconActivated(QSystemTrayIcon::ActivationReason))); But i received a segfault on this code. Any ideas? P.S. Sorry for my bad english. ...
I want to find in an adjacency graph from the bgl how give a Vertexdescriptor and get the set of nodes that are parents of this given node. i would like to do this in directed graph, it seems you could use a bidirectional graph but i want to be able to restrict it so that there are no cycles. ...
What allocators are available out there for use with STL when dealing with small objects. I have already tried playing with pool allocators from Boost, but got no performance improvement (actually, in some cases there was considerable degradation). ...
Example user input: PA1 9 //correct PJ1 9 //wrong, error printed "Invalid row" because it is not between A and I PA11 9 //wrong, error printer "Invalid column" because it is not between 1 and 9. The problem I am having is that it should clear the remaining input and then ask for the user to enter the "move" again, and it is not. Wh...
I have a question on constant objects. In the following program: class const_check{ int a; public: const_check(int i); void print() const; void print2(); }; const_check::const_check(int i):a(i) {} void const_check::print() const { int a=19; cout<<"The value in a is:"<<a; } void const_check::print2() { int ...
In the interpreter for my experimental programming language I have a symbol table. Each symbol consists of a name and a value (the value can be e.g.: of type string, int, function, etc.). At first I represented the table with a vector and iterated through the symbols checking if the given symbol name fitted. Then I though using a map,...
After some studying, I created a small app that calculates DFTs (Discrete Fourier Transformations) from some input. It works well enough, but it is quite slow. I read that FFTs (Fast Fourier Transformations) allow quicker calculations, but how are they different? And more importantly, how would I go about implementing them in C++? ...
I'm trying to use Qt to download the html code from the following url: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=nucleotide&cmd=search&term=AB100362 this url will re-direct to www.ncbi.nlm.nih.gov/nuccore/27884304 I try to do it by following way, but I cannot get anything. it works for some webpage such as www.google....
hello i try out opengl. i have a programm that creates a black border an white corner (quadrangle). now i want to make the corner of the quadrangle in an different color. i don't know where exactly to write the code, and i don't know much a but color4f, i searcherd on google, but didn't get it. (is there a good description somewhere?)...
Keep in mind, if you choose to answer the question, I am a beginner in the field of programming and may need a bit more explanation than others as to how the solutions work. Thank you for your help. My problem is that I am trying to do computations with parts of a string (consisting only of numbers), but I do not know how to convert a...
Suppose I have: Foo foo; is there a shorthand for this? foo.operator->().operator()(1, 2); ...
what is the use of using declaration type of namespacing over using directive type of namespacing??when to use each one of them? ...
I work on a large application, and frequently use WinDbg to diagnose issues based on a DMP file from a customer. I have written a few small extensions for WinDbg that have proved very useful for pulling bits of information out of DMP files. In my extension code I find myself dereferencing c++ class objects in the same way, over and ove...
I'm wondering how to implement what is stated in the title. I've tried something like... std::for_each( a.begin(), a.end(), std::mem_fun_ref( &myClass::someFunc ) ) but I get an error saying that the "term" (I"m assuming it means the 3rd argument) doesn't evaluate to a function with 1 argument, even though someFunc does take one argume...