c++

memset on array of structures in C++

I have another memset question. It appears as if the code I am editing may have some issues (or it's not done the same way in different files) A::LRM las[9]; //A and LRM are both structures with BOOLS and INTS memset(&las, 0, sizeof(las)); typedef Sec SecArray[16]; SecArray rad_array; memset(rad_array, 0, sizeof(SecArray)); The secon...

Passing data structures to different threads

I have an application that will be spawning multiple threads. However, I feel there might be an issue with threads accessing data that they shouldn't be. I'm relatively new to threading so bare with me. Here is the structure of the threaded application (sorry for the crudeness): MainThread / ...

C++0x thread interruption

According to the C++0x final draft, there's no way to request a thread to terminate. That said, if required we need to implement a do-it-yourself solution. On the other hand boost::thread provides a mechanism to interrupt a thread in a safe manner. In your opinion, what's the best solution? Designing your own cooperative 'interruption...

2-byte (UCS-2) wide strings under GCC

Hi all, when porting my Visual C++ project to GCC, I found out that the wchar_t datatype is 4-byte UTF-32 by default. I could override that with a compiler option, but then the whole wcs* (wcslen, wcscmp, etc.) part of RTL is rendered unusable, since it assumes 4-byte wide strings. For now, I've reimplemented 5-6 of these functions fro...

Using custom dll in Qt Application

First, my compiler and OS: Qt Creator 1.3 Qt 4.6 (32 bit) Windows 7 Ultimate I want to learn how to create and import a dll in Qt. I've created a *.dll file using Qt Creator, called Shared1.dll which contains nothing but an empty class named Shared1. Now I'd like to use Shared1 class in another Qt project. How can I do that? Thanks ...

"Expected initializer before '<' token" in header file

I'm pretty new to programming and am generally confused by header files and includes. I would like help with an immediate compile problem and would appreciate general suggestions about cleaner, safer, slicker ways to write my code. I'm currently repackaging a lot of code that used to be in main() into a Simulation class. I'm getting a c...

error of integer overflow

This the part of my OpenGL code, I am getting an error for : struct Ball { float x; float y; float rot; float dir; bool rmv; Ball* next; }; Ball* curBall; void addBall() { if (balls==NULL) { balls=new Ball; balls->next=NULL; curBall=balls; } else { curBall->next=new Ball; ...

How to program a connection pool?

Is there a known algorithm for implementing a connection pool? If not what are the known algorithms and what are their trade-offs? What design patterns are common when designing and programming a connection pool? Are there any code examples implement a connection pool using boost.asio? Is it a good idea to use a connection pool for persi...

What is time complexity for find method in a set in c++?

set<int> s; s.insert(1); s.insert(2); ... s.insert(n); I wonder how much time it takes for s.find(k) where k is a number from 1..n? I assume it is log(n). Is it correct? ...

Shall I bother with QT?

Guys I study C++ for a second year. Till now I was doing only console app but I think it's a time to start programming in Windows. There are few alternatives and Qt is one of them but I'm also drawn towards pure Windows API - for more power of course. What would you suggest? ...

Practise Questions for Templates,Functors,CallBack functions in c++?

Hi, I have been reading templates,functors,callback function for the past week and have referred some good books and articles. I however feel that, unless I can get good practice - programming in templates and use functors-callbacks there is no way I can really understand all the concepts or fluently use them while coding. Could any...

which is better in general, map or vector in c++?

As I know that accessing an element in vector takes constant time while in map takes logarithmic time. However, storing a map takes less memory than storing a vector. Therefore, I want to ask which one is better in general? I'm considering using one of those two in my program, which has about 1000 elements. I plan to use 3 dimensional v...

How to get forkpty/execvp() to properly handle redirection and other bash-isms?

Hi all, I've got a GUI C++ program that takes a shell command from the user, calls forkpty() and execvp() to execute that command in a child process, while the parent (GUI) process reads the child process's stdout/stderr output and displays it in the GUI. This all works nicely (under Linux and MacOS/X). For example, if the user enters...

Random numbers from binomial distribution

I need to generate quickly lots of random numbers from binomial distributions for dramatically different trial sizes (most, however, will be small). I was hoping not to have to code an algorithm by hand (see, e.g., this related discussion from November), because I'm a novice programmer and don't like reinventing wheels. It appears Boost ...

STL operator= behavior change with Visual Studio 2010?

Hi, I am attempting to compile QtScriptGenerator (gitorious) with Visual Studio 2010 (C++) and have run into a compile error. In searching for a solution, I have seen occasional references to compile breakages introduced since VS2008 due to changes in VS2010's implementation of STL and/or c++0x conformance changes. Any ideas what is h...

C++ Memory allocation question involving vectors

vector< int > vect; int *int_ptr = new int(10); vect.push_back( *int_ptr ); I under stand that every "new" needs to be followed by a "delete" at some point but does the clear() method clean this memory? What about this method of doing the same thing: vector< int > vect; int int_var = 10; vect.push_back( int_var ); From what I under...

How do you delete a pointer without deleting the data the pointer points to?

I have a pointer that points to an array and another pointer referencing the same array. How do i delete any one of those pointers without killing the array such that the second undeleted pointer still works? for example: int* pointer1 = new int [1000]; int* pointer2; pointer2 = pointer1; Now i want to get rid of pointer1, how would ...

How to choose an integer linear programming solver ?

Hi all, I am newbie for integer linear programming. I plan to use a integer linear programming solver to solve my combinatorial optimization problem. I am more familiar with C++/object oriented programming on an IDE. Now I am using NetBeans with Cygwin to write my applications most of time. May I ask if there is an easy use ILP solver f...

Initilizing a static class member that depends on a private template type (C++)

Hi, I have the following situation: class Test { private: class SubType { //... }; static std::vector<SubType> v; }; Because v is static, I initilize it in the cpp file with std::vector<Test::SubType> Test::v; But this does not work, the compiler tells me that "Test::SubType" is private. What can I do about thi...

Passing C++ object to C++ code through Python?

Hi all, I have written some physics simulation code in C++ and parsing the input text files is a bottleneck of it. As one of the input parameters, the user has to specify a math function which will be evaluated many times at run-time. The C++ code has some pre-defined function classes for this (they are actually quite complex on the mat...